DESIGN OF A STANDALONE PHOTOVOLTAIC BASED MINI-GRID TO MEET

THE ELECTRICAL LOAD DEMAND OF DOTA COMMUNITY,

GWAGWALADA ABUJA

BY

ABDULSALAM ABDULRAHMAN ABAYOMI

MTECH/SET/2022/12979

DEPARTMENT OF BUILDING

FEDERAL UNIVERSITY OF TECHNOLOGY

MINNA
 CHAPTER ONE

1.0 INTRODUCTION

The global challenge of energy access remains a significant impediment to sustainable

development, particularly in rural areas of developing countries. Despite tremendous

progress in electrification, the International Renewable Energy Agency in 2019 stated that

more than half of Nigeria's rural population still lacks access to electricity (Idoko et al., 2024).

This gap is partly due to rural area’s physical isolation, which presents considerable hurdles

to the expansion of the national grid infrastructure.

The absence of a stable power supply in Dota community in Gwagwalada, Abuja, is

symptomatic of a broader challenge plaguing Nigeria's electric power sector. These issues

encompass insufficient generation capacity, aging transmission infrastructure, rampant

energy theft, and an ever-increasing demand for electricity (Aguda, 2023). Furthermore, the

environmental ramifications of conventional fossil fuel-based electricity generation have

necessitated a paradigm shift towards more sustainable energy solutions.

In response to these multifaceted challenges, there is a growing emphasis on decentralized

generation (DG) strategies, particularly mini-grids and micro-grids powered by renewable

energy sources. This shift is further bolstered by recent legislative changes, notably the

constitutional amendment bill signed into law on March 17, 2023, which devolves power

generation, transmission, and distribution to Nigeria's 36 states (Idoko et al., 2024). This

legislative framework provides a conducive environment for the proliferation of renewable

energy-based off-grid and mini-grid solutions in unserved and underserved areas.

Mini-grids, defined as localized power generation and distribution systems, offers a

promising solution for rural electrification (Saleh, 2024). These systems typically comprise

of an electricity production unit, often coupled with energy storage capabilities, and a
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distribution network serving isolated loads. The autonomy of mini-grids allows for

independent control and management without compromising the stability of the conventional

grid.

Among the array of renewable energy technologies available for mini-grid applications which

includes wind, biomass, tidal, hydroelectric, and geothermal, solar photovoltaic (PV) systems

have emerged as a particularly viable option (Akash et al, 2024). This preference is

underpinned by the rapid technological advancements in photovoltaic technology, its

inherent cleanliness, and its improving efficiency (Ghosh et al, 2021). Moreover, the

geographical location of Nigeria confers a significant solar energy advantage. The country

experiences high solar irradiation levels, with daily averages ranging from 3.5 kWh/m² in

coastal regions to 7.0 kWh/m² in the northern territories (Olagunju, 2021). This abundant

solar resource renders Photovoltaic-based mini-grids an ideal alternative to grid electricity

across both rural and urban landscapes of Nigeria.

A typical PV-based mini-grid system comprises of several key components which includes

PV modules for converting solar radiation into direct current (DC) electricity, inverters for

DC to alternating current (AC) conversion, battery storage systems for energy management,

and a distribution network (Khoirunnisa, 2024). The integration of these components creates

a robust, scalable, and environmentally friendly power solution capable of meeting the

diverse energy needs of Dota community and other rural communities.

The design and implementation of such systems, however, require careful consideration of

various technical, economic, and social factors. These include accurate load demand

assessment and forecasting, optimal sizing of system components, efficient energy

management strategies, and the integration of smart grid technologies for enhanced reliability

and performance.
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This research, therefore, aims to address the electricity access challenge in Dota community

by leveraging cutting-edge renewable energy technologies to develop a sustainable and

replicable solution for rural electrification through the design of a standalone PV-based mini-

grid system. The outcomes of this research are expected to contribute significantly to the

body of knowledge on rural electrification strategies and provide valuable insights for

policymakers, energy planners, and practitioners in the field of renewable energy deployment

in Nigeria and beyond.

1.2 Statement of the Problem

In Nigeria, the electricity access deficit is particularly acute, with the World Bank estimating

that 85 million Nigerians lack access to grid electricity, representing 43% of the country's

population (Bisu et al., 2024). The situation is even more dire in rural areas, where only 36%

of the population has access to electricity, compared to 55% in urban areas (Odoi-Yorke,

2024). This urban-rural disparity is exemplified by communities like Dota in Gwagwalada,

Abuja, which remain unconnected to the national grid.

The absence of reliable electricity, restricts access to modern energy services for residents of

Dota who are compelled to rely on traditional and often hazardous energy sources. The use

of kerosene lamps for lighting, and diesel generators for electricity supply for instance, not

only poses significant health risks due to indoor air pollution but also contributes to

greenhouse gas emissions.

Furthermore, the economic implications of energy poverty in Dota community are profound.

The lack of reliable electricity severely constrains economic and productive activities,

limiting income-generating opportunities and perpetuating a cycle of poverty. A study by the

Rocky Mountain Institute (2018) found that access to reliable electricity can increase

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household incomes by up to 39% in rural African communities. The absence of such access

in Dota community thus represents a significant opportunity cost for local economic

development.

The quality of life of the residents is also significantly affected by the lack of reliable

electricity as it compromises the quality and availability of medical services particularly for

procedures requiring refrigeration, sterilization, or electronic medical equipment, contributes

to lower educational outcomes and reduced long-term economic prospects for the

community's youth.

While the extension of the national grid to remote communities like Dota is often proposed

as a solution, it faces significant challenges. The Nigerian Rural Electrification Agency (REA)

estimates that grid extension costs can range from $8,000 to $10,000 per kilometer (Nnaji et

al., 2024). Given Dota's remote location, this approach is likely to be economically unfeasible

and logistically challenging. In light of these challenges, there is an urgent need for an

alternative, sustainable solution to address the electricity deficit in Dota community, and

Photovoltaic (PV) based mini-grids have emerged as a promising solution for rural

electrification.

1.3 Aim and Objectives

1.3.1 Aim

The primary aim of this research is to design a sustainable, standalone photovoltaic-based

mini-grid system to address the electricity demand of Dota community in Gwagwalada,

Abuja.

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1.3.2 Objectives

i. To conduct a comprehensive electrical load assessment and forecasting in Dota community,

encompassing residential, commercial, and public service requirements, which will serve as

the foundational reference point for determining the capacity and configuration of the mini-

grid system.

ii. To identify, size and select the main components of the photovoltaic-based mini-grid

system.

iii. To optimize the system using HOMER Pro simulation software, ensuring technical

feasibility and economic viability.

iv. To provide a detailed system design and implementation guidelines for the photovoltaic

based mini grid.

1.4 Justification of the Study

The implementation of a photovoltaic-based mini-grid in Dota community is justified by

several compelling factors.

Firstly, it addresses the critical need for reliable and uninterrupted power supply, which is

often lacking in conventional grid systems. This improvement in energy access is expected

to significantly enhance the quality of life for residents by enabling modern conveniences

and essential services.

Secondly, the project has the potential to catalyze local economic development. By providing

a stable power supply, it can foster the growth of small businesses, improve agricultural

processes, and enhance food storage and processing capabilities. These advancements are

likely to create employment opportunities, boost productivity, and increase income levels

within the community, contributing to broader economic growth in Nigeria.

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Furthermore, the adoption of renewable energy technology aligns with global efforts to

combat climate change. By replacing fossil fuel-based energy sources with clean solar power,

the project will contribute to reducing greenhouse gas emissions. This aspect not only

benefits the local environment but also positions Dota as a model for sustainable rural

development.

Lastly, the success of this project could serve as a replicable model for other rural

communities in Nigeria facing similar energy challenges, potentially informing policy

decisions and future rural electrification initiatives.

1.5 Scope and Limitations

1.5.1 Scope

The scope of this study encompasses the comprehensive design of a standalone photovoltaic-

based mini-grid system for Dota community. It takes into account the specific geographical

and demographic characteristics of the area, as well as the current and projected electricity

demand patterns. The design process includes system sizing, component selection, system

optimization and distribution network layout.

1.5.2 Limitation

Firstly, the project is confined to the design phase only and does not extend to the actual

installation or implementation of the mini-grid system. Secondly, the mini-grid being

designed as a standalone system, does not consider future integration with the national grid.

Lastly, while the methodology may be adaptable, the specific design is tailored to Dota

community and may not be directly applicable to other locations without modifications.

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1.6 Study Area

Dota community is predominantly a farming community located in Dobi ward, about 20km

from Gwagwalada metropolis, Abuja. The coordinates are latitude 9.0634 N and longitude

6.5509 E. It is a rural/remote settlement with a population of approximately 400 people. The

community's primary economic activities include agriculture, small-scale trading, and

artisanal services. Due to its remote location, Dota community has no access to the national

power grid, resulting in a high dependence on traditional energy sources, such as kerosene

lamps for lighting and firewood for cooking, which have health, economic, and

environmental drawbacks.

The climate in Dota is predominantly tropical with average temperatures ranging from 23°C-

36°C and an average annual solar irradiance of 5.5 kWh/m²/day. This favorable solar

potential makes the area suitable for photovoltaic (PV) power generation.

The community’s electricity demand includes residential lighting, phone/rechargeable lamp

charging, small appliances, and in some cases, productive uses such as submersible pump for

water pumping and refrigeration units for local businesses. The absence of a reliable and

sustainable energy source hinders socioeconomic growth and impacts the quality of life in

Dota community.

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Figure 1.1: Google earth image showing the study Area

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 CHAPTER TWO

2.0 LITERATURE REVIEW

2.1. Current status of electricity in Nigeria

The electricity sector in Nigeria has been grappling with significant challenges in recent years,

characterized by inadequate power generation, inefficient distribution, and frequent power

outages. Recent studies have provided valuable insights into the current state of the sector

and potential pathways for improvement.

A comprehensive assessment of off-grid power plants in Nigeria has revealed both promising

developments and persistent challenges in addressing the country's power shortages. The

study, which examined the location, capacity, performance, and current status of these

facilities, found that off-grid solutions have demonstrated significant potential in alleviating

energy deficits. However, despite these advancements, a substantial gap between supply and

demand continues to exist. This finding underscores the critical need for sustained investment

and expansion in off-grid technologies as a complementary measure to the national grid

infrastructure. The research highlights the importance of a diversified approach to energy

provision in Nigeria, combining centralized and decentralized solutions to meet the growing

power demands of the population (IA et al., 2024).

Understanding consumer behavior is crucial for effective energy planning and distribution

strategies. Ubani et al. (2024) investigated household electricity consumption determinants

in major Nigerian cities, shedding light on the factors that influence energy usage patterns.

Their research emphasizes the importance of tailoring energy policies and infrastructure

development to meet the specific needs and consumption habits of different urban

populations.

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The fragility of Nigeria's power grid remains a significant concern, as highlighted by Amadi

and Ekeng (2024) in their critical analysis of voltage collapse incidents. Their study

underscores the urgent need for infrastructure upgrades and improved grid management to

enhance the reliability of power supply across the country. Addressing these technical

challenges is crucial for ensuring a stable and consistent electricity supply to both urban and

rural areas.

In the context of renewable energy development, Idoko et al. (2024) conducted a comparative

analysis of renewable energy policies between Nigeria and the USA. Their research identified

significant disparities in policy frameworks and implementation strategies, suggesting that

Nigeria could benefit from adopting more robust and comprehensive renewable energy

policies to accelerate the transition to cleaner energy sources.

The efficiency of electricity distribution companies in Nigeria varies substantially across

different regions, as revealed by Olanrele (2024) evaluation. This study highlights the need

for improved regulatory oversight and performance benchmarking to enhance the overall

efficiency of the distribution sector. Standardizing best practices and implementing

performance-based incentives could help address these disparities and improve service

delivery.

With their performance assessment of Nigeria's power distribution and generation, Adoghe

et al. (2023) offered a comprehensive picture of the industry. In order to overcome enduring

barriers in the industry, their research highlighted both opportunities and challenges,

highlighting the necessity of strategic investments in infrastructure and capacity building.

Looking towards the future, Pavanelli et al. (2023) proposed an institutional framework for

energy transitions, drawing lessons from the history of Nigeria's electricity industry. Their

study underscores the importance of robust institutional structures and governance

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mechanisms in facilitating a successful energy transition. Implementing such a framework

could provide the necessary support for the adoption of renewable energy technologies and

the modernization of the electricity sector.

These recent studies collectively paint a picture of a sector in transition, facing significant

challenges but also presenting opportunities for improvement and innovation. Addressing the

identified issues will require a multifaceted approach, involving policy reforms,

technological advancements, and strategic investments in both conventional and renewable

energy sources.

2.1.2. Electricity Act of 2023

The Electricity Act of 2023 marks a significant turning point in Nigeria's efforts to overhaul

and modernize its electricity sector, introducing comprehensive reforms aimed at addressing

long-standing challenges and promoting sustainable development. At its core, the Act seeks

to create a more competitive and efficient electricity market by unbundling the sector and

encouraging private sector participation. It establishes a new regulatory framework that

separates generation, transmission, and distribution activities, allowing for greater

specialization and efficiency in each segment. The Act also introduces provisions for

independent power producers (IPPs) to enter the market, fostering competition and

potentially improving the overall quality and reliability of electricity supply. A key feature

of the Act is its emphasis on renewable energy development, setting targets for renewable

energy integration into the national grid and providing incentives for clean energy projects.

This includes mechanisms such as feed-in tariffs, tax incentives, and streamlined permitting

processes for renewable energy installations, which could significantly accelerate Nigeria's

transition to cleaner energy sources (Idehen and Oyemwense, 2024).

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Furthermore, the Electricity Act of 2023 addresses critical issues of governance and oversight

in the sector. It strengthens the powers and independence of the Nigerian Electricity

Regulatory Commission (NERC), empowering it to enforce regulations more effectively and

ensure fair competition in the market. The Act also introduces provisions for improved

transparency and accountability in the sector, including requirements for regular reporting

and auditing of electricity companies. Another significant aspect of the Act is its focus on

rural electrification and off-grid solutions, recognizing the need to improve electricity access

in underserved areas. It establishes a framework for mini-grids and standalone systems,

potentially accelerating electrification in rural and peri-urban areas. The Act also addresses

issues of consumer protection, setting standards for service quality and introducing

mechanisms for dispute resolution between consumers and electricity providers. However,

as Ogugbara (2024) points out, the success of these reforms will largely depend on effective

implementation and enforcement of the new regulatory framework. This includes building

institutional capacity, ensuring regulatory independence, and maintaining policy consistency

over time. While the Act provides a solid foundation for transforming Nigeria's electricity

sector, realizing its full potential will require sustained commitment from all stakeholders,

including government agencies, private sector participants, and consumers.

2.1.3 Overview of Rural Electrification

Rural electrification has emerged as a crucial strategy for addressing energy poverty and

promoting socio-economic development in Nigeria's rural areas. The assessment of off-grid

power plants, which play a significant role in rural electrification efforts, has provided

valuable insights into their performance and potential for expansion (IA et al., 2024). These

findings underscore the importance of decentralized energy solutions in reaching remote

communities.
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The regulatory landscape plays a critical role in the success of rural electrification initiatives.

Research exploring the connections between mini-grid market regulation and energy access

expansion in Nigeria has emphasized the importance of supportive regulatory frameworks in

facilitating the growth of mini-grid solutions for rural electrification (Sesan et al., 2024). This

highlights the need for policy makers to create an enabling environment for private sector

participation in rural electrification projects.

The transformative potential of rural electrification extends beyond mere access to electricity.

A study examining the effect of basic amenities, including electricity, on the socio-economic

development of rural areas in Benue State, Nigeria, underscored the significant impact of

electrification on improving living standards and economic opportunities in rural

communities (Atungwu, 2024). This research demonstrates the far-reaching benefits of rural

electrification in driving overall rural development.

Innovative solutions are emerging to address the electricity crisis in sub-Saharan Africa,

including Nigeria. The proposal of photovoltaic mini-grid incorporation as a potential

solution has highlighted the technical and economic viability of solar-powered mini-grids in

addressing rural electrification challenges (Cyril et al., 2024). This approach offers a

sustainable and scalable model for expanding electricity access in remote areas.

Strategic planning is essential for achieving universal electricity access in line with

Sustainable Development Goal 7 (SDG7). The employment of a GIS-based model to explore

strategies for achieving this goal has provided valuable insights into the spatial planning

aspects of rural electrification initiatives in Nigeria (Isihak, 2023). Such tools can help

optimize the deployment of electrification projects and ensure equitable access across

different regions.

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The quality of electricity supply remains a significant concern in rural electrification efforts.

An investigation into electricity supply quality and use among rural and peri-urban

households and small firms in Nigeria revealed significant disparities in electricity access

and quality between urban and rural areas (Pelz et al., 2023). These findings emphasize the

need for targeted interventions to not only expand access but also improve the reliability and

quality of electricity supply in rural areas.

2.1.4 Importance of Rural Electrification

The importance of rural electrification extends far beyond the mere provision of electricity,

encompassing a wide range of social, economic, and developmental impacts. While direct

studies on Nigeria are limited, research from other developing countries offers valuable

insights that can be applied to the Nigerian context.

A comprehensive analysis of rural electrification benefits from women's perspectives in rural

Nepal revealed significant positive impacts on gender equality and women's empowerment

(Shrestha et al., 2023). This study highlighted how access to electricity can transform

traditional gender roles, providing women with more opportunities for education,

entrepreneurship, and participation in community decision-making. Although conducted in

Nepal, these findings have relevance for understanding the potential social benefits of rural

electrification in Nigeria, particularly in addressing gender disparities in rural areas.

A global review of policies and case studies related to rural electrification has identified both

challenges and successes, emphasizing the multifaceted benefits for rural communities

(Omole et al., 2024). This research underscored improvements in education, healthcare, and

economic opportunities as key outcomes of rural electrification. In the context of education,

electrification enables extended study hours and access to digital learning resources. For

healthcare, it facilitates the use of modern medical equipment and improves the storage of
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vaccines and medications. Economically, electrification can spur the growth of small

businesses and enhance agricultural productivity through mechanization.

Furthermore, rural electrification plays a crucial role in reducing urban-rural migration. A

study in India found that improved electricity access in rural areas significantly decreased the

likelihood of youth migration to urban centers (Rao, 2023). This finding has implications for

Nigeria, suggesting that rural electrification could help balance population distribution and

reduce pressure on urban infrastructure.

The environmental benefits of rural electrification, particularly when coupled with renewable

energy sources, are also significant. Research in sub-Saharan Africa has shown that

transitioning from traditional biomass fuels to clean electricity can substantially reduce

indoor air pollution and associated health risks (Adegbulugbe et al., 2024). This transition

not only improves public health but also contributes to forest conservation by reducing

reliance on wood fuel.

Rural electrification has been linked to improved food security and agricultural productivity.

A study in Ethiopia demonstrated that electrified rural areas experienced higher crop yields

and greater food diversity due to improved irrigation systems and food preservation

techniques (Gebreegziabher et al., 2023). Similar benefits could be realized in Nigeria's

agricultural sector, contributing to national food security goals.

Lastly, the psychological and social impacts of rural electrification should not be

underestimated. Research in Bangladesh found that access to electricity significantly

improved perceived quality of life and social cohesion in rural communities (Rahman et al.,

2024). This suggests that beyond tangible economic benefits, rural electrification can enhance

overall well-being and community satisfaction.

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These diverse studies collectively illustrate the transformative potential of rural

electrification across various aspects of rural life. While challenges in implementation remain,

the wide-ranging benefits underscore the importance of prioritizing rural electrification

initiatives in Nigeria's development agenda.

2.1.5 Challenges faced in Electrifying Remote Areas

The electrification of remote areas in Nigeria faces a multitude of challenges that hinder the

expansion of reliable electricity access to rural communities. These obstacles span across

technical, financial, logistical, and regulatory domains, requiring a multifaceted approach to

overcome them.

Financial constraints represent one of the most significant barriers to rural electrification. The

high costs associated with extending grid infrastructure to remote locations often make

traditional electrification methods economically unfeasible. A comprehensive review of rural

electrification challenges by Omole et al. (2024) highlighted that the limited ability of rural

households to pay for electricity services further complicates the financial viability of

electrification projects. This financial hurdle necessitates innovative funding models and

cost-effective technological solutions to make rural electrification economically sustainable.

Technical limitations pose another set of challenges in electrifying remote areas. The lack of

adequate infrastructure, including transmission and distribution networks, makes it difficult

to deliver reliable power to distant rural communities. Stephanie et al. (2024) examined the

impact of stand-alone systems in Nigeria's energy distribution sector, emphasizing the

technical challenges these systems face, such as intermittency issues with renewable energy

sources and the need for robust energy storage solutions. Their research underscored the

importance of addressing these technical barriers to ensure the reliable operation of

decentralized energy systems in rural areas.

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Logistical difficulties in reaching remote locations add another layer of complexity to rural

electrification efforts. The absence of proper roads and transportation infrastructure in many

rural areas of Nigeria makes it challenging to transport equipment and conduct maintenance

operations. This logistical challenge not only increases the cost of electrification projects but

also affects their long-term sustainability by complicating ongoing maintenance and repair

efforts (Omole et al., 2024).

The regulatory environment also plays a crucial role in the success of rural electrification

initiatives. Stephanie et al. (2024) highlighted the importance of addressing regulatory

barriers to facilitate the widespread adoption of decentralized energy solutions in rural areas.

The lack of clear policies and regulatory frameworks can create uncertainty for investors and

project developers, hindering the implementation of rural electrification projects.

In response to these challenges, innovative approaches are being explored. Olaniyan et al.

(2024) investigated the potential of frugal energy generation using e-waste components as a

strategy for addressing rural electrification challenges in Nigeria. This approach aims to

leverage locally available resources and reduce costs, demonstrating the need for creative

solutions to overcome financial barriers.

To address the complex interplay of challenges in rural electrification, Juanpera et al. (2020)

proposed a multicriteria-based methodology for designing rural electrification systems, using

Nigeria as a case study. Their approach considered various factors, including technical,

economic, and social criteria, to optimize the design and implementation of rural

electrification projects. This holistic methodology highlights the importance of considering

multiple perspectives when developing strategies to overcome rural electrification challenges.

Thus, while the challenges faced in electrifying remote areas in Nigeria are significant, they

are not insurmountable. Addressing these obstacles requires a combination of innovative

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technologies, sustainable financing models, supportive regulatory frameworks, and context-

specific solutions that take into account the unique characteristics of each rural community.

By tackling these challenges comprehensively, Nigeria can make significant strides in

expanding electricity access to its rural population, unlocking the numerous benefits

associated with rural electrification.

2.2.1 Overview of Renewable Energy Sources and Potential in Nigeria

Nigeria, with its diverse geographical features and abundant natural resources, possesses

significant potential for renewable energy development. There are various renewable energy

sources available in Nigeria, including solar, biomass, hydro, geothermal, and wind energy.

2.2.1.1 Solar Energy and Potential in Nigeria

Nigeria's geographical location near the equator endows it with abundant solar resources,

making it one of the most promising renewable energy sources for the country. As noted by

Chanchangi et al. (2023), Nigeria receives an average of 6.5 hours of sunshine daily, with

solar radiation ranging from 3.5 to 7.0 kWh/m²/day across different regions. This high level

of solar insolation positions Nigeria as an ideal location for both small-scale and large-scale

solar energy projects.

The potential for solar energy in Nigeria is vast and largely untapped. The northern regions

of the country, particularly states like Sokoto, Kano, and Borno, receive the highest levels of

solar radiation, making them prime locations for utility-scale solar farms. However, even the

southern regions with relatively lower solar radiation still have sufficient potential for

distributed solar systems, including rooftop photovoltaic (PV) installations and solar water

heaters.

The applications of solar energy in Nigeria are diverse, they range from off-grid solutions for

rural electrification to grid-connected systems for urban areas. Solar home systems and mini-
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grids have shown particular promise in providing electricity access to remote communities

not connected to the national grid. In urban areas, solar PV systems can help reduce the

dependency on unreliable grid power and diesel generators, contributing to both energy

security and environmental sustainability.

Despite the enormous potential, the adoption of solar energy in Nigeria faces several

challenges. These include high initial costs, lack of technical expertise, and inadequate policy

frameworks. However, with declining costs of solar technologies globally and increasing

government attention to renewable energy, the prospects for large-scale solar energy

development in Nigeria are improving.

2.2.1.2 Biomass and Potential in Nigeria

Biomass energy represents a significant untapped potential in Nigeria's renewable energy

landscape. As a country with a strong agricultural sector and vast forested areas, Nigeria has

abundant biomass resources that can be harnessed for energy production. Jekayinfa et al.

(2020) provided a comprehensive assessment of these resources, highlighting their potential

contribution to Nigeria's energy mix.

The primary sources of biomass energy in Nigeria include:

i. Nigeria's agricultural sector produces substantial amounts of crop residues such as rice

husks, corn cobs, groundnut shells, and cassava peels. These residues, often considered

waste, can be converted into valuable energy sources through various technologies like

direct combustion, gasification, or anaerobic digestion.

ii. Nigeria's forests generate significant amounts of woody biomass from logging and

wood processing activities. These residues can be used for heat and electricity

generation.

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iii. With a large and growing urban population, Nigeria produces substantial amounts of

municipal solid waste. This waste, when properly managed, can be a valuable source

of energy through waste-to-energy technologies.

iv. Nigeria's livestock sector produces considerable amounts of animal waste, which can

be used to generate biogas through anaerobic digestion.

The potential applications of biomass energy in Nigeria are diverse (Ukoba et al., 2024).

They include electricity generation through biomass power plants, production of biogas for

cooking and lighting in rural areas, and the production of biofuels for transportation. Biomass

energy could play a crucial role in Nigeria's energy transition, particularly in rural areas where

it can provide a sustainable alternative to traditional biomass use (such as firewood), which

often leads to deforestation and indoor air pollution.

However, the development of Nigeria's biomass energy sector faces challenges such as the

need for efficient collection and transportation systems for biomass resources, the

requirement for significant initial investments in biomass energy technologies, and the need

for supportive policies and regulations. Addressing these challenges could unlock the vast

potential of biomass energy in Nigeria, contributing to energy security, rural development,

and environmental sustainability.

2.2.1.3 Hydro Energy and Potential in Nigeria

Hydropower represents one of the most established forms of renewable energy in Nigeria,

with a long history of exploitation. However, the country's hydropower potential remains

largely untapped, offering significant opportunities for expansion. Nigeria's hydropower

potential is estimated at over 14,000 MW, of which only a fraction is currently being utilized

(Birhanu, 2023).

Nigeria's hydropower resources can be categorized into three main types:

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 i. Large-scale hydropower: This includes existing facilities like the Kainji (760 MW),

Jebba (570 MW), and Shiroro (600 MW) dams on the Niger River. Several other large-

scale projects are in various stages of planning or development, such as the Mambilla

project (3,050 MW) on the Benue River.

ii. Small hydropower: Nigeria has numerous small rivers and streams suitable for small

hydropower projects (typically defined as less than 30 MW). The Energy Commission

of Nigeria has identified over 278 unexploited small hydropower sites with a total

potential of 734.3 MW.

iii. Run-of-river hydropower: These are hydroelectric systems that harness the energy of

flowing rivers without the need for large reservoir impoundments. They have less

environmental impact compared to large dams and could be suitable for many of

Nigeria's smaller rivers.

The potential benefits of expanding Nigeria's hydropower capacity are significant.

Hydropower can provide baseload electricity, which is crucial for grid stability. It can also

contribute to flood control, irrigation, and water supply. Furthermore, hydropower's ability

to quickly respond to demand fluctuations makes it valuable for grid balancing, especially as

more variable renewable sources like solar and wind are integrated into the grid (Zhao et al.,

2023).

However, the development of Nigeria's hydropower resources faces challenges. These

include high initial capital costs, long project development timelines, potential environmental

and social impacts (especially for large dams), and the need for careful water resource

management in the face of climate change. Additionally, seasonal variations in water flow

can affect the reliability of hydropower, particularly for run-of-river projects. Despite these

challenges, the vast untapped potential of hydropower in Nigeria presents a significant

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 opportunity for increasing the country's renewable energy capacity and improving its overall

energy security.

2.2.1.4 Geothermal Energy and Potential in Nigeria

Geothermal energy is one of the less explored renewable energy sources in Nigeria, but it

holds potential, particularly in certain regions of the country. Geothermal energy harnesses

heat from the earth's crust to generate electricity or provide direct heating (Baymatov, 2023).

While Nigeria is not located in a major geothermal zone like countries along the East African

Rift System, there are indications of geothermal potential in some areas. The most promising

regions for geothermal energy in Nigeria include:

i. The Benue Trough: This is a major geological formation extending from the Niger

Delta in the south to the Chad Basin in the north. Some studies have indicated the

presence of hot springs and other geothermal manifestations in this region.

ii. The Jos Plateau: This area in central Nigeria has been identified as having some

geothermal potential due to its volcanic history and the presence of hot springs.

iii. The Ikogosi Warm Springs area in Ekiti State: While primarily known as a tourist

attraction, this natural warm spring also indicates geothermal activity in the region.

The potential applications of geothermal energy in Nigeria could include:

i. Electricity generation: In areas with sufficient heat resources, geothermal power plants

could provide baseload electricity.

ii. Direct use applications: Lower temperature geothermal resources could be used for

direct heating in agriculture (e.g., greenhouse heating), industrial processes, or for spa

and tourism purposes.

iii. Ground source heat pumps: Even in areas without high-temperature resources, ground

source heat pumps could be used for efficient heating and cooling of buildings.
23
However, it's important to note that compared to other renewable energy sources like solar

and biomass, the geothermal potential in Nigeria is limited and less well-understood.

Significant research and exploration would be needed to fully assess and develop Nigeria's

geothermal resources. The development of geothermal energy in Nigeria would require

substantial investment in exploration, drilling, and technology, as well as capacity building

in geothermal energy expertise.

While geothermal energy may not play a major role in Nigeria's overall energy mix in the

near future, it could potentially contribute to local energy solutions in specific areas where

resources are identified. Further research and feasibility studies are needed to better

understand and potentially exploit Nigeria's geothermal energy resources.

2.2.1.5 Wind Energy and Potential in Nigeria

Wind energy represents another promising renewable energy source for Nigeria, although its

potential is not as uniformly distributed as solar energy. The potential for wind energy in

Nigeria varies significantly across different regions of the country, with some areas showing

high potential while others have limited resources.

According to studies, including the work by Owebor et al. (2021), the most promising areas

for wind energy development in Nigeria include:

i. Northern States: States such as Kano, Katsina, and Bauchi have been identified as

having significant wind energy potential. These areas often experience higher wind

speeds due to their topography and climate.

ii. Coastal Areas: The coastal regions of Nigeria, particularly in states like Lagos, Ondo,

and Akwa Ibom, have shown potential for offshore and onshore wind energy

development. The consistent sea breezes in these areas provide a reliable wind

resource.
24
iii. Plateau Regions: The Jos Plateau in Plateau State has been identified as having good

wind energy potential due to its elevated terrain.

The wind speeds in these promising areas typically range from 4.0 to 7.5 meters per second

at 10 meters height, which is generally considered suitable for wind energy generation.

However, it's important to note that wind speeds increase with height, and modern wind

turbines often operate at heights of 80-100 meters or more, where wind speeds are likely to

be higher.

The potential applications of wind energy in Nigeria include:

i. Grid-connected wind farms: Large-scale wind farms could be developed in areas with

high wind potential to feed electricity into the national grid.

ii. Off-grid and mini-grid systems: In remote areas with good wind resources, wind

turbines could be used as part of hybrid systems (often combined with solar PV and

battery storage) to provide reliable off-grid electricity.

iii. Water pumping: Wind-powered water pumps could be used for irrigation and water

supply in rural areas, particularly in the northern regions where water scarcity is a

significant issue.

Despite its potential, wind energy development in Nigeria faces several challenges:

i. Variability of wind resources: Wind speeds can vary significantly both daily and

seasonally, necessitating careful site selection and often requiring hybrid systems or

energy storage solutions.

ii. High initial costs: While the costs of wind energy have decreased globally, the initial

investment for wind projects remains high, particularly for the importation of turbines

and other equipment.

25
iii. Technical expertise: There is a need for capacity building in wind energy technology,

from resource assessment to turbine maintenance.

iv. Grid integration: The variable nature of wind energy presents challenges for

integration into Nigeria's often unstable grid system.

v. Policy and regulatory framework: Like other renewable energy sources, wind energy

development in Nigeria would benefit from more robust and consistent policy support.

While wind energy may not have the same breadth of potential as solar energy in Nigeria, it

represents an important component of a diversified renewable energy portfolio. Particularly

in regions with high wind potential, wind energy could play a significant role in increasing

Nigeria's renewable energy capacity and improving energy access. Further detailed wind

resource assessments and feasibility studies are needed to fully capitalize on Nigeria's wind

energy potential.

2.2.2 Benefits of Renewable Energy

The adoption of renewable energy systems in Nigeria offers a myriad of benefits that extend

far beyond the energy sector itself. These benefits span environmental, economic, and social

dimensions, collectively contributing to a more sustainable and prosperous future for the

nation.

From an environmental perspective, the transition to renewable energy sources promises

significant reductions in greenhouse gas emissions and air pollution. This shift is crucial for

Nigeria's efforts to mitigate climate change impacts and preserve its natural ecosystems. The

conservation of natural resources, particularly fossil fuels, through the adoption of

renewables aligns with global sustainability goals and positions Nigeria as a responsible

global actor in the fight against climate change.

26
Economically, the renewable energy sector presents substantial opportunities for job creation

and economic diversification. As highlighted by Ibrahim et al. (2021) in their comparative

review of renewable energy production in Africa, the development of a robust renewable

energy industry can stimulate economic growth, reduce dependence on fossil fuel imports,

and potentially position Nigeria as an energy exporter to neighboring countries. Moreover,

the decreasing costs of renewable energy technologies promise long-term cost savings for

both consumers and the government.

The adoption of renewable energy systems also holds significant implications for Nigeria's

energy security. By diversifying its energy sources, Nigeria can reduce its vulnerability to

supply disruptions and price fluctuations in the global fossil fuel market. The decentralized

nature of many renewable energy technologies, particularly solar and small-scale

hydropower, enhances grid resilience and offers opportunities for community-owned energy

projects, fostering a sense of energy independence at local levels.

Socially, the expansion of renewable energy capacity presents a pathway to improved

electricity access in rural and underserved areas. This has far-reaching implications for

quality of life, education, healthcare, and economic opportunities in these communities. The

potential for community-owned energy projects further enhances social cohesion and

empowerment, aligning with broader development goals.

Despite these numerous benefits, the widespread adoption of renewable energy in Nigeria

faces several challenges, as noted by Adewuyi (2020) in a study focusing on bioethanol and

biodiesel production. These challenges include financial constraints, limited technical

expertise, inadequate policy frameworks, infrastructure limitations, and issues of public

awareness and acceptance. Addressing these challenges requires a multi-stakeholder

approach involving government, private sector, academia, and international partners.

27
Nigeria's abundant renewable energy resources present a significant opportunity to address

the country's energy challenges while promoting sustainable development. By leveraging

these resources and addressing the associated challenges through comprehensive policies,

financial incentives, capacity building, and infrastructure development, Nigeria can transition

towards a cleaner, more reliable, and more inclusive energy system. This transition not only

promises to meet the country's growing energy demands but also to contribute significantly

to its economic growth, environmental sustainability, and overall quality of life for its citizens.

2.3 Overview of Photovoltaic (PV) Technology

Photovoltaic (PV) technology harnesses the power of sunlight to generate electricity, offering

a clean and renewable energy source. The fundamental principle of PV technology is the

photovoltaic effect; whereby certain materials generate an electric current when exposed to

light. This effect was first observed by Alexandre-Edmond Becquerel in 1839, marking the

beginning of a technological journey that has led to the modern solar cells we use today

(Marques Lameirinhas et al., 2022).

Solar cells, the building blocks of PV systems, are typically made from semiconductor

materials, with silicon being the most common. These cells are designed to absorb photons

from sunlight and release electrons, creating an electric current. The efficiency of this process

has been steadily improving over the years, with current commercial silicon-based solar cells

achieving efficiencies of around 15-22% (Al-Ezzi et al., 2022).

The evolution of PV technology has seen significant advancements in materials,

manufacturing processes, and cell designs. From the early silicon-based cells to emerging

technologies like perovskite and multi-junction cells, the field continues to push the

boundaries of efficiency and cost-effectiveness (Hepp et al., 2024). These advancements

28
have made PV systems increasingly viable for a wide range of applications, from small-scale

residential installations to large utility-scale solar farms.

2.3.1 Types of PV Systems (Standalone, Grid-tied, Hybrid)

PV systems can be categorized into three main types based on their connection to the power

grid and energy storage capabilities:

2.3.1.1 Standalone Systems

Also known as off-grid systems, these are designed to operate independently of the power

grid. They typically include battery storage to provide power during periods of low sunlight.

Standalone systems are particularly useful in remote areas where grid connection is not

feasible or economical. Odou et al. (2020) demonstrated the viability of hybrid off-grid

renewable power systems for sustainable rural electrification in Benin, highlighting the

potential of standalone PV systems in addressing energy access challenges in remote areas.

Figure 2.1: General stand-alone power system (Odou et al., 2020)

29
2.3.1.2 Grid-tied Systems:

These systems are connected to the public electricity grid. They can feed excess power back

into the grid when generation exceeds consumption and draw power from the grid when

needed. Grid-tied systems are common in urban and suburban areas with reliable grid access.

Mishra et al. (2023) conducted a study on the optimal sizing and assessment of grid-tied

hybrid renewable energy systems for rural electrification, showcasing the potential of these

systems in complementing existing grid infrastructure.

Figure 2.2: Direct utility-grid tied PV system (Mishra et al., 2023).

2.3.1.3 Hybrid Systems

These systems combine PV technology with other energy sources, such as wind turbines or

diesel generators, and often include battery storage. Hybrid systems offer increased reliability

and flexibility, making them suitable for a wide range of applications. Dost Mohammadi and

Gezegin (2024) investigated the feasibility of hybrid systems combining PV, wind, and

biomass for rural electrification in Afghanistan, demonstrating the potential of these

integrated solutions in addressing complex energy needs.

30
Figure 2.3: Schematic diagram of the hybrid solar photovoltaic (PV)/wind turbine
(WT)/biomass generator (BG)-powered cellular network (Dost Mohammadi et al., 2024)
2.3.2 Components of a PV System

A typical Photovoltaic system consists of several key components which includes the

following

2.3.2.1 Photovoltaic Modules:

These are the primary components that convert sunlight into electricity. Modules are

composed of multiple solar cells connected in series and parallel to achieve the desired

voltage and current output. Recent advancements in module technology have focused on

improving efficiency and reducing costs (Fazal et al., 2023).

PV Module Technologies may be in any of the following forms:

2.3.2.1.1 Monocrystalline Silicon Modules

Monocrystalline silicon modules are made from single-crystal silicon wafers. These modules

are known for their high efficiency and sleek, uniform appearance.

31
 Key features:

i. Highest efficiency among commercial modules (typically 17-22%)

ii. Uniform dark color, often black or dark blue

iii. Excellent performance in low-light conditions

iv. Higher cost compared to other technologies

Figure 2.4: Cross-section of a Monocrystalline Silicon Solar Cell (Source: Fazal et

al., 2023).

2.3.2.1.2 Polycrystalline Silicon Modules

Polycrystalline (or multicrystalline) silicon modules are made from multiple silicon crystals

melted together (Di Sabatino et al., 2024). They offer a balance between cost and efficiency.

Key features:

i. Slightly lower efficiency than monocrystalline (typically 15-17%)

ii. Distinctive blue color with a speckled pattern

iii. Lower production costs than monocrystalline

iv. Good performance in various light conditions

32
Figure 2.5: Structure of a Polycrystalline Silicon Solar Cell (Source: Di Sabatino et al.,

2024).

2.3.2.1.3 Thin Film Technologies

Thin film modules are made by depositing one or more thin layers of photovoltaic material

on a substrate. The most common materials are amorphous silicon (a-Si), cadmium telluride

(CdTe), and copper indium gallium selenide (CIGS) (Dolma et al., 2024).

Key features:

i. Lower efficiency than crystalline silicon (typically 10-12% for commercial modules)

ii. Flexible and lightweight, suitable for diverse applications

iii. Lower production costs

iv. Better performance in low light and high temperature conditions

v. Potential for semi-transparency (useful for building-integrated PV)

33
Figure 2.6: (a) The typical structure of thin-film solar cells and (b) the schematic
representation of the working mechanism of the solar cell (Dolma et al., 2024).

Each of these technologies has its advantages and is suited to different applications.

Monocrystalline modules are often preferred where space is limited and high efficiency is

crucial. Polycrystalline modules offer a good balance of cost and performance for many

applications. Thin film technologies are versatile and can be used in situations where

flexibility or light weight is important, or where large areas need to be covered at lower cost.

Recent advancements, as noted by Fazal & Rubaiee (2023), have focused on improving the

efficiency of all these technologies while reducing production costs. This has led to the

development of new cell architectures, improved manufacturing processes, and the use of

novel materials, all contributing to the increasing competitiveness of solar PV as an energy

source.

2.3.2.2 Inverters

These devices convert the direct current (DC) produced by the PV modules into alternating

current (AC) suitable for use in homes and businesses. Modern inverters often include

34
advanced features such as maximum power point tracking (MPPT) to optimize system

performance (Allouhi et al., 2023).

Inverters play a crucial role in PV systems by not only converting DC to AC but also by

optimizing the overall system performance. Modern inverters have evolved to become

sophisticated power electronics devices with multiple functionalities. In addition to MPPT,

which ensures that the PV modules operate at their most efficient voltage and current points,

inverters often incorporate grid-interactive features for grid-tied systems. These features

include anti-islanding protection, which prevents the inverter from feeding power into the

grid during outages, ensuring safety for utility workers. Many advanced inverters also offer

power quality improvements, such as reactive power control and harmonic mitigation,

contributing to grid stability. Furthermore, smart inverters with communication capabilities

enable remote monitoring and control, allowing for real-time system performance analysis

and fault detection. Some inverters are designed with integrated energy storage management,

facilitating seamless integration with battery systems in hybrid PV installations. The

continuous advancements in inverter technology, including the development of wide-

bandgap semiconductor-based inverters, are driving improvements in efficiency, power

density, and reliability, further enhancing the overall performance and cost-effectiveness of

PV systems (Lazaroiu et al., 2023).

35
 Figure 2.7: Inside the solar inverter (Allouhi et al., 2023).

Figure 2.8: Simple inverter working principle (Lazaroiu et al., 2023).

2.3.2.2.1 Inverter Technologies in Solar PV Systems

The choice of inverter technology significantly impacts system efficiency, reliability, and

overall performance. Below are the various inverter technologies:

2.3.2.2.1.1 Transformer-based (Low Frequency) Inverters

Transformer-based inverters use a large iron-core transformer to step up the voltage and

provide galvanic isolation between the DC and AC sides of the system (Xiang, 2024). The

inverter first converts the DC input to a low-voltage AC, which is then stepped up to the

required grid voltage by the transformer.

36
Key features of Transformer-based inverters:

i. Robust and reliable design

ii. Provide galvanic isolation, enhancing safety

iii. Can handle high DC input voltages

iv. Well-suited for harsh environments and outdoor installations

v. Typically, heavier and bulkier than other inverter types

vi. Slightly lower efficiency (usually 93-95%) due to transformer losses

Applications of Transformer-based inverters:

i. Large commercial and utility-scale solar installations

ii. Environments with stringent safety requirements

iii. Locations with unstable grid conditions

2.3.2.2.1.2 Transformerless (High Frequency) Inverters

Transformerless inverters use advanced electronic switching techniques to achieve the

necessary voltage conversion without a bulky transformer (Kibria et al., 2023). They often

employ high-frequency switching and may use a small high-frequency transformer for

isolation.

Key features of Transformerless inverters:

i. Lighter and more compact design

ii. Higher efficiency (up to 98%) due to reduced conversion losses

iii. No low-frequency transformer, resulting in lower material costs

iv. More sensitive to grid fluctuations

v. May require additional safety measures due to lack of galvanic isolation

vi. Often feature advanced grid support functions

37
 The applications of Transformerless inverters include:

i. Residential and commercial rooftop installations

ii. Weight-sensitive installations (e.g., rooftops with limited load-bearing capacity)

iii. Regions with stable grid conditions and appropriate safety regulations

Figure 2.9: Compact Transformerless Inverter Mounted on a Wall (Kibria et al., 2023)

2.3.2.2.2 Microinverters

Microinverters are small inverters attached to individual solar panels or small groups of

panels. They convert DC to AC at the panel level, allowing for panel-level optimization and

monitoring (Lagarde et al., 2023).

Key features of microinverters include:

i. Optimize performance of each panel independently

ii. Improve system performance in partial shading conditions

iii. Easy to expand system size

iv. Enhanced safety with low-voltage DC on the roof

v. Higher cost per watt compared to string inverters

vi. Longer warranty periods (often 25 years)

38
vii. Built-in panel-level monitoring

Applications of micro inverters:

i. Residential and small commercial installations

ii. Systems with complex roof geometries or partial shading

iii. Installations where future expansion is likely

Figure 2.10. Microinverter Attached to the Back of a Solar Panel (Lagarde et al., 2023).

The choice of inverter technology depends on various factors including system size, local

regulations, environmental conditions, and specific project requirements. As solar PV

technology continues to advance, inverter technologies are evolving to improve efficiency,

reduce costs, and provide additional functionalities to support the growing needs of modern

power systems.

2.3.2.3 Batteries

In off-grid and hybrid systems, batteries store excess energy for use during periods of low

sunlight. The development of more efficient and cost-effective battery technologies has been

crucial in improving the viability of PV systems for rural electrification (Odou et al., 2020).

39
Battery technologies play a crucial role in off-grid and hybrid photovoltaic (PV) systems,

enabling energy storage for use during periods of low sunlight or high demand. The

development of more efficient and cost-effective battery technologies has significantly

improved the viability of PV systems for rural electrification and grid stabilization.

2.3.2.3.1 Lead-Acid Batteries: Lead-acid batteries have been the traditional choice for PV

systems due to their reliability, low cost, and wide availability (Ryś, et al., 2024). These

batteries come in two main types: flooded (or wet-cell) and sealed (including Absorbed Glass

Mat [AGM] and Gel). Flooded lead-acid batteries require regular maintenance, including

water replenishment and equalization charges, but offer a long lifespan when properly

maintained.

Figure 2.11: Flooded lead-acid battery (Ryś et al., 2024).

Sealed lead-acid batteries, on the other hand, are maintenance-free and can be installed in

various orientations. However, they generally have a shorter lifespan compared to their

flooded counterparts.

40
 Figure 2.12: Sealed lead-acid battery (Ryś et al., 2024).

Lead-acid batteries are known for their robustness and ability to deliver high surge currents,

making them suitable for starting engines in addition to energy storage. However, they have

relatively low energy density, limited depth of discharge (typically 50%), and shorter cycle

life compared to newer technologies. Despite these limitations, lead-acid batteries remain a

popular choice for many PV installations, especially in cost-sensitive applications or where

advanced battery management systems are not available.

2.3.2.3.2 Lithium-Ion Batteries: Lithium-ion batteries have gained significant traction in

recent years due to their high energy density, longer cycle life, and improved performance

characteristics. These batteries come in various chemistries, including Lithium Iron

Phosphate (LiFePO4), Lithium Nickel Manganese Cobalt Oxide (NMC), and Lithium

Titanate (LTO) (Chen et al., 2024).

41
 Fig. 2.13: Lithium-Ion Solar Batteries (Chen et al., 2024).

Lithium-ion batteries offer several advantages over lead-acid batteries:

i. Higher energy density, allowing for more storage capacity in a smaller space

ii. Deeper depth of discharge (up to 80-90%)

iii. Longer cycle life (typically 2000-5000 cycles or more)

iv. Higher charge and discharge efficiency

v. Lower self-discharge rates

vi. Faster charging capabilities

vii. No maintenance requirements

However, lithium-ion batteries are generally more expensive upfront, although their longer

lifespan and better performance often result in a lower total cost of ownership over time.

They also require sophisticated battery management systems (BMS) to ensure safe operation

and optimal performance. The use of lithium-ion batteries in PV systems has enabled more

compact and efficient energy storage solutions, particularly beneficial for residential and

commercial applications where space is at a premium.

2.3.2.3.3 Nickel-Based Batteries: Nickel-Cadmium (NiCd) and Nickel-Metal Hydride

(NiMH) batteries have been used in some PV systems, particularly in extreme temperature

conditions. NiCd batteries are known for their robustness, ability to withstand deep
42
discharges, and excellent performance in low temperatures (Azzouz et al., 2023). However,

their use has declined due to environmental concerns related to cadmium toxicity and the

"memory effect" that can reduce their effective capacity over time.

Figure 2.14: Nickel Cadmium Battery 1.2v 5000mah (Azzouz et al., 2023).

NiMH batteries offer improved energy density and are more environmentally friendly

compared to NiCd, but they have higher self-discharge rates and are less tolerant of

overcharging. Both NiCd and NiMH batteries have largely been superseded by lithium-ion

technologies in modern PV systems.

The choice of battery technology for a PV system depends on various factors including cost,

performance requirements, environmental conditions, and system size. While lead-acid

batteries continue to be used in many applications due to their low cost and reliability,

lithium-ion batteries are increasingly becoming the preferred choice for their superior

performance characteristics. Emerging technologies like flow batteries and sodium-based

batteries offer potential alternatives, particularly for large-scale applications. As research and

development in battery technologies continue, we can expect further improvements in energy

density, cycle life, and cost-effectiveness, further enhancing the viability of PV systems for

a wide range of applications.

43
2.3.2.4 Charge Controllers

Charge controllers are essential components in PV systems with battery storage, playing a

crucial role in maintaining the health and longevity of the battery bank. These devices act as

intermediaries between the PV modules and the batteries, regulating the flow of electricity to

prevent overcharging, which can lead to battery damage, reduced lifespan, and potential

safety hazards. Similarly, charge controllers protect batteries from deep discharging, a

condition that can significantly degrade battery capacity and performance over time. Modern

charge controllers employ sophisticated algorithms to optimize the charging process, often

implementing multi-stage charging protocols that include bulk, absorption, and float stages.

This approach ensures that batteries are charged efficiently and maintained at their optimal

state of charge.

Figure 2.15: 30A 12/24V PWM Charge Controller (Odou et al., 2020).

Advanced charge controllers have evolved to incorporate additional features that enhance

system performance and flexibility. Many now include MPPT (Maximum Power Point

Tracker) functionality, similar to that found in inverters, which can increase energy harvest

44
from PV modules by up to 30% compared to traditional pulse width modulation (PWM)

controllers, especially in conditions of varying sunlight or temperature (Odou et al., 2020).

Figure 2.16: Victron Energy SCC110030210 Smart Solar MPPT 100/30 Charge
Controller (Odou et al., 2020).
Some charge controllers also offer programmable settings that allow for customization based

on specific battery chemistries and system requirements. Integration capabilities with energy

management systems enable remote monitoring and control, providing users with real-time

data on system performance and battery status. Furthermore, advanced charge controllers

may include load management features, allowing for intelligent control of connected loads

based on available energy and battery state of charge. This functionality is particularly

valuable in off-grid systems, where efficient energy use is critical for system reliability and

longevity.

2.3.2.5 Mounting Structures:

Mounting structures are essential components of photovoltaic (PV) systems, designed to

provide secure support for solar panels while maximizing their exposure to sunlight. For

rooftop installations, these structures are typically classified into two main categories: flush-

mounted systems that are installed parallel to the roof surface, and tilted systems that allow

45
for adjustment of the panel angle to optimize solar exposure (Panjawani et al., 2020). The

engineering of rooftop mounting systems requires careful consideration to ensure even

weight distribution of the panels, resistance to wind loads, and preservation of the roof's

structural integrity. In areas prone to heavy snowfall, special design considerations are

implemented to facilitate snow shedding and prevent excessive load accumulation.

Figure 2.17: Rooftop Solar Panel Installations (Ogbuefi et al., 2020).

The field of mounting structures has seen significant innovation beyond traditional rooftop

installations. Carport PV systems have gained popularity, serving the dual purpose of

providing shade for vehicles and a platform for solar energy generation, particularly in

parking areas of commercial and institutional buildings. In utility-scale ground-mounted

installations, solar trackers are frequently employed. These advanced mounting structures are

programmed to follow the sun's trajectory throughout the day, substantially increasing energy

yield compared to fixed-tilt systems (Salunkhe & Mulani, 2024).

Urban environments with limited space have seen the emergence of building-integrated

photovoltaics (BIPV). This innovative approach incorporates PV modules directly into

46
building materials such as facades, windows, or roofing tiles, serving both as a power

generator and a functional element of the building envelope. The development of these

diverse mounting solutions reflects the adaptability and growing integration of solar

technology across various architectural and environmental contexts.

2.3.2.5 Balance of System (BOS) Components:

The Balance of System (BOS) components are crucial elements in a photovoltaic (PV) system,

encompassing all parts of the solar power system other than the photovoltaic panels

themselves (Abou Jieb et al., 2022). This includes a wide array of electrical components

essential for system operation and safety. Wiring is a fundamental BOS component,

responsible for connecting the various elements of the system and transmitting electricity

from the panels to the inverter and ultimately to the point of use or grid connection. Switches

play a vital role in system control and safety, allowing for the isolation of different parts of

the system when necessary for maintenance or in case of emergencies (Abed, 2024).

Other critical electrical components include combiner boxes, which consolidate the output

from multiple solar panels; surge protection devices to safeguard against voltage spikes; and

monitoring systems that track the performance and health of the PV installation. Additionally,

BOS components often include mounting hardware, inverters for converting DC to AC power,

and in some cases, energy storage systems like batteries (Abou Jieb et al., 2022).

47
 Figure 2.18: Balance of Solar PV Systems (BOS) (Abou Jieb et al., 2022).

The design and selection of BOS components are critical to the overall efficiency, reliability,

and longevity of a solar power system, as they can significantly impact system performance

and maintenance requirements. As the solar industry continues to evolve, innovations in BOS

components are focusing on improving durability, reducing costs, and enhancing overall

system integration and smart functionality (Abed, 2024).

2.3.3 Benefits of PV Systems for Rural Electrification

PV systems offer numerous benefits for rural electrification:

i. PV systems can be deployed in remote areas where grid extension is not feasible,

providing access to electricity for previously unserved communities (Odou et al., 2020).

ii. PV systems can be scaled from small household installations to larger community-

based systems, allowing for flexible deployment based on local needs and resources

(Mishra et al., 2023).

iii. Once installed, PV systems have minimal operating costs, making them economically

attractive for long-term rural electrification projects (Dost Mohammadi et al., 2024).

iv. PV systems produce clean energy with minimal environmental impact during operation.

Bošnjaković et al. (2023) conducted a comprehensive study on the environmental

48
 impact of PV power systems, highlighting their potential to reduce greenhouse gas

emissions and contribute to sustainable development goals.

v. By harnessing locally available solar resources, PV systems can reduce dependence on

imported fuels and centralized power generation, enhancing energy security in rural

areas (Odou et al., 2020).

vi. Access to reliable electricity through PV systems can catalyze economic activities,

improve education and healthcare services, and enhance overall quality of life in rural

communities (Mishra et al., 2023).

PV technology offers a promising solution for rural electrification, combining technological

advancements with environmental and socio-economic benefits. As research continues to

improve efficiency, reduce costs, and optimize system designs, PV systems are poised to play

an increasingly significant role in addressing global energy access challenges.

2.4 Mini-grid Systems

Mini-grid systems have emerged as a promising solution for rural electrification, particularly

in developing countries where extending the main grid to remote areas is often economically

unfeasible. These decentralized power systems typically combine renewable energy sources,

such as solar photovoltaics, with energy storage and distribution networks to provide reliable

electricity to isolated communities. Recent studies have demonstrated the potential of mini-

grids to significantly improve energy access and quality of life in rural areas.

The performance and reliability of off-grid PV mini-grid systems in rural tropical Africa have

been a subject of increasing interest among researchers. A case study conducted in southern

Ethiopia by Wassie et al. (2023) provided valuable insights into the challenges and

opportunities associated with implementing such systems in remote locations. Their analysis

highlighted the importance of proper system sizing, load management, and maintenance
49
practices to ensure long-term sustainability. The study also emphasized the need for

community engagement and capacity building to maximize the benefits of mini-grid

installations

2.4.1 Classification of Mini Grids based on Energy Sources:

Mini grid systems can be classified based on their primary energy sources.

2.4.1.1 Photovoltaic (PV) Mini-Grids

Photovoltaic mini-grids harness solar energy using solar panels to generate electricity. These

systems have gained significant popularity due to the decreasing costs of solar technology

and their scalability (Falope, Lao, Hanak & Huo, 2024). PV mini-grids typically consist of

solar panels, inverters, charge controllers, and battery storage systems.

Key features of Photovoltaic (PV) Mini-Grids:

i. Modular and scalable design

ii. Low operational costs due to free solar energy

iii. Environmentally friendly with zero emissions during operation

iv. Suitable for areas with good solar irradiation

v. Requires battery storage to provide power during nighttime and cloudy periods

vi. Performance can be affected by seasonal variations in solar irradiance

PV mini-grids are particularly well-suited for rural electrification in sunny regions, offering

a clean and sustainable energy solution. Recent advancements in solar panel efficiency,

battery technology, and smart inverters have further improved the viability of PV mini-grids.

2.5.1.2 Wind-Powered Mini-Grids:

Wind-powered mini-grids utilize wind turbines to convert wind energy into electricity. These

systems are ideal for areas with consistent wind resources (Ogunniyi et al., 2024).

50
 Figure 2.17: Wind-Powered Mini-Grids (Ogunniyi et al., 2024).

Key features of Wind-Powered Mini-Grids:

i. Can generate power day and night, given sufficient wind speeds

ii. Suitable for coastal areas or regions with steady wind patterns

iii. Requires careful site selection based on wind resource assessment

iv. May have higher initial costs compared to PV systems

v. Can be combined with other energy sources for improved reliability

vi. Potential for visual and noise impacts on the surrounding environment

Wind-powered mini-grids can be highly effective in areas with strong and consistent wind

resources. However, their application is more geographically limited compared to solar PV

systems.

2.5.1.3 Hybrid Mini-Grids:

Hybrid mini-grids combine two or more energy sources to enhance system reliability and

efficiency (Zarmai et al., 2024). Common combinations include:

51
 i. Solar PV + Wind: This combination leverages the complementary nature of solar and

wind resources. Solar panels generate power during the day, while wind turbines can

continue to produce electricity at night or during cloudy periods.

ii. Solar PV + Diesel Generator: This hybrid system uses solar PV as the primary energy

source, with a diesel generator serving as backup during periods of low solar

production or high demand. This configuration can significantly reduce fuel

consumption compared to diesel-only systems.

iii. Wind + Diesel Generator: Similar to the PV-diesel hybrid, this system uses wind as

the primary source with diesel backup.

iv. Solar PV + Wind + Diesel Generator: This triple hybrid system offers high reliability

by combining three different energy sources.

v. Hybrid systems often include battery storage to smooth out fluctuations in renewable

energy production and reduce reliance on fossil fuel generators.

2.5.1.4 Biomass-based Mini-Grids:

Biomass mini-grids use organic matter (e.g., agricultural waste, wood chips, or purpose-

grown energy crops) as fuel to generate electricity. These systems can be particularly suitable

for agricultural communities with access to biomass resources.

Key features:

i. Can provide baseload power

ii. Utilizes local waste materials, promoting circular economy principles

iii. Requires a steady supply of biomass fuel

iv. May have higher operational complexity compared to solar or wind systems

v. Can be combined with waste heat recovery for improved efficiency

52
2.5.1.5 Micro-Hydro Mini-Grids:

Micro-hydro systems harness the energy of flowing water in rivers or streams to generate

electricity. These systems are highly site-specific and depend on the availability of suitable

water resources (Zarmai et al., 2024).

i. Key features of Micro-Hydro Mini-Grids:

ii. Can provide consistent baseload power

iii. Low operational costs once installed

iv. Long lifespan with proper maintenance

v. Limited by geographical constraints and water availability

vi. May have environmental impacts on local ecosystems

vii. Seasonal variations in water flow can affect power output

2.5.1.6 Geothermal Mini-Grids

In areas with geothermal resources, mini-grids can be powered by geothermal energy (Zebra

et al., 2021). While less common due to geographical limitations, geothermal mini-grids can

provide reliable baseload power.

Key features of Geothermal Mini-Grids:

i. Consistent power output independent of weather conditions

ii. High-capacity factor

iii. Limited to areas with accessible geothermal resources

iv. Higher initial costs due to exploration and drilling requirements

v. Potential for long-term, low-cost energy production

53
2.5.1.7 Tidal and Wave Energy Mini-Grids:

For coastal communities, tidal and wave energy can be harnessed to power mini-grids (Denial,

2023). While still in the early stages of commercialization, these technologies offer potential

for predictable and consistent energy generation.

Key features of Tidal and Wave Energy Mini-Grids:

i. Predictable energy generation based on tidal patterns

ii. High power density compared to wind and solar

iii. Limited by geographical constraints

iv. Technology still in development, with higher costs compared to more mature renewable

sources

The choice of energy source for a mini-grid depends on various factors including local

resource availability, geographical conditions, energy demand patterns, and economic

considerations. Many modern mini-grid systems adopt a hybrid approach, combining

multiple energy sources to optimize reliability, efficiency, and cost-effectiveness.

Advancements in control systems, energy management, and storage technologies have

greatly enhanced the capabilities of mini-grids across all these classifications. Smart grid

technologies, including advanced metering infrastructure (AMI) and demand-side

management, are increasingly being integrated into mini-grid systems to improve their

performance and sustainability.

As technology continues to evolve and costs decrease, mini-grids based on renewable energy

sources are becoming increasingly viable solutions for electrification in remote and rural

areas, contributing significantly to global efforts towards universal energy access and

sustainable development.

54
2.5.1 Socio-economic Impacts of Mini-grid Systems

The benefits of mini-grid systems in rural electrification extend beyond mere energy

provision. Duran and Sahinyazan (2021) conducted a comprehensive analysis of renewable

mini-grid projects, highlighting their multifaceted impact on rural communities. Their study

revealed that well-designed mini-grid systems can stimulate local economic development,

improve educational outcomes, enhance healthcare services, and contribute to gender

equality. These socio-economic benefits underscore the transformative potential of mini-

grids as a tool for sustainable development in underserved regions.

In the context of Sub-Saharan Africa, where energy access remains a significant challenge,

PV mini-grids have been identified as a potential panacea for the electricity crisis. Cyril et al.

(2024) argued that the incorporation of photovoltaic mini-grids could address the persistent

energy shortages in the region. Their research highlighted the technical feasibility and

economic viability of such systems, particularly in light of declining solar PV costs and

advancements in energy storage technologies. The authors emphasized the need for

supportive policy frameworks and innovative financing mechanisms to accelerate the

deployment of mini-grids across Sub-Saharan Africa.

2.5.2 Best Practices and Recommendations for mini-grid systems

Drawing from the lessons learned and best practices observed in various mini-grid projects,

several key recommendations emerge for designing and implementing PV mini-grids in rural

areas. Firstly, a thorough assessment of local energy needs and resources is critical to ensure

appropriate system sizing and technology selection. Secondly, the involvement of local

communities in all stages of project development, from planning to operation, is essential for

fostering ownership and ensuring long-term sustainability. Thirdly, the adoption of flexible

55
and modular system designs can facilitate future expansions and adaptations to changing

energy demands.

Furthermore, the integration of productive uses of energy into mini-grid projects can enhance

their economic viability and developmental impact. By promoting energy-dependent

businesses and value-added activities, mini-grids can create a virtuous cycle of economic

growth and increased electricity demand. Additionally, the implementation of smart

technologies, such as advanced metering and remote monitoring systems, can improve

operational efficiency and enable data-driven decision-making.

PV mini-grids represent a promising solution for accelerating rural electrification and

fostering sustainable development in underserved regions. As demonstrated by numerous

case studies and research findings, these systems have the potential to deliver reliable,

affordable, and clean energy to remote communities. However, realizing this potential

requires a holistic approach that addresses technical, economic, social, and regulatory aspects.

2.6. Load Estimation and Forecasting

Electricity demand forecasting plays an important role in load allocation and planning for

future generation facilities and transmission augmentation. Load demand in a given season

is subject to a range of uncertainties, including underlying population growth, climate change

and economic conditions. In addition, historical data are of importance in demand forecasting.

Load forecasting can be divided into three categories: short-term forecasts, medium-term

forecasts and long term forecasts.

56
2.5.2 Techniques for Load Estimation and Forecasting

Load estimation and forecasting are critical components in the design and operation of mini-

grid systems, particularly in rural areas where electricity consumption patterns can be volatile.

These techniques aim to predict future load demands, typically expressed as:

L(t) = f (X₁, X₂, ..., Xₙ) [2.1]

where L(t) is the load at time t, and X₁, X₂, ..., Xₙ are various influencing factors such as

historical load data, weather conditions, and socio-economic indicators.

Ahmad et al. (2022) provided a comprehensive survey of load forecasting techniques,

categorizing them into traditional statistical methods and advanced machine learning

approaches. Traditional methods often employ time series analysis, such as Autoregressive

Integrated Moving Average (ARIMA) models:

ARIMA (p,d,q): Φₚ (B) (1-B)ᵈyₜ = θq(B)εₜ [2.2]

where B is the backshift operator, Φₚ(B) is the autoregressive operator of order p, (1-B)ᵈ

represents differencing of order d, and θq(B) is the moving average operator of order q.

Ali et al. (2020) proposed an estimated parameterized fuzzy inference system for load

forecasting in smart grids. Their approach can be represented as:

y = f (x; θ) [2.3]

where y is the predicted load, x is the input vector, and θ represents the fuzzy system

parameters.

Habbak et al. (2023) emphasized the importance of hybrid models, which combine multiple

forecasting techniques. A general form of a hybrid model can be expressed as:

L(t) = w₁f₁ (X) + w₂f₂ (X) + ... + wₙfₙ (X) [2.4]

where fᵢ(X) represents individual forecasting models and

wᵢ are the corresponding weights.

57
Nti et al. (2020) highlighted the growing importance of machine learning algorithms, such as

Artificial Neural Networks (ANNs) and Support Vector Machines (SVMs). The output of an

ANN can be represented as:

y = φ (∑ᵢwᵢxᵢ + b) [2.5]

where φ is the activation function, wᵢ are the weights, xᵢ are the inputs, and b is the bias term.

Haben et al. (2021) recommended probabilistic forecasting methods for low voltage load

forecasting. These methods provide a probability distribution of future load values, often

expressed as quantiles:

Q (τ|X) = F⁻¹ (τ|X) [2.6]

where Q (τ|X) is the τ-th quantile of the load distribution conditioned on input X, and F⁻¹ is

the inverse cumulative distribution function.

2.5.2 Energy Consumption Patterns in Rural Communities

Understanding energy consumption patterns in rural communities requires analysis of various

factors influencing electricity demand. Chowdhury et al. (2020) developed a data-driven

approach that can be adapted to rural contexts. Their method integrates multiple data sources

to characterize energy consumption:

E = f (S, D, C) [2.7]

where E is energy consumption, S represents spatial factors, D denotes demographic

characteristics, and C accounts for climatic conditions.

Akintande et al. (2020) examined determinants of renewable energy consumption in African

nations, employing econometric models such as:

lnREC = β₀ + β₁lnGDP + β₂lnURB + β₃lnTRADE + ε [2.8]

where REC is renewable energy consumption, GDP is gross domestic product, URB is

urbanization rate, TRADE represents trade openness, and ε is the error term.
58
Yin and Zhao (2023) investigated energy development in rural China, emphasizing the need

for integrated approaches. They proposed a framework that considers the coupling between

energy utilization (EU), environmental impacts (EI), and rural development (RD):

C = {(EU × EI × RD) / [(EU + EI + RD) / 3]³} (1/3) [2.9]

where C is the coupling coordination degree.

Wassie and Ahlgren (2024) analyzed load profiles of PV mini-grid customers in rural off-

grid East Africa. They employed load disaggregation techniques to identify distinct

consumption patterns:

L(t) = ∑ᵢ Lᵢ(t) + ε(t) [2.10]

where L(t) is the total load at time t, Lᵢ(t) represents individual appliance loads, and ε(t) is the

residual term.

Zhong et al. (2024) explored the relationship between energy utilization and rural

sustainability using a coupling coordination degree approach similar to Yin and Zhao's, but

with a focus on atmospheric (A), ecological (E), and socioeconomic (S) factors:

D = √(C × T) [2.11]

where D is the coupling coordination degree, C is the coupling degree, and T is the

comprehensive evaluation index of A, E, and S.

2.7 Principles of PV System Design

The design of photovoltaic (PV) systems for mini-grids in rural areas requires a

comprehensive understanding of various technical principles and considerations. At the core

of PV system design is the accurate assessment of energy demand and supply. The system

must be capable of meeting the load requirements of the community it serves while

considering the available solar resource. This balance is typically expressed through the

energy balance equation:

59
E_PV(t) = E_L(t) + E_B(t) + E_Loss(t) [2.12]

Where E_PV(t) represents the energy generated by the PV array at time t, E_L(t) is the load

energy demand, E_B(t) denotes the energy stored in or drawn from the battery system, and

E_Loss(t) accounts for system losses.

The sizing of the PV array is a critical aspect of system design. It involves determining the

required number and configuration of PV modules to meet the energy demand. The array

capacity is typically calculated using the following equation:

P_array = (E_daily × SF) / (η_system × PSH) [2.13]

Where P_array is the required array power, E_daily represents the daily energy demand, SF

is a safety factor (usually 1.1 to 1.3), η_system is the overall system efficiency, and PSH

denotes the Peak Sun Hours at the location.

The selection of appropriate PV modules is crucial and depends on various factors including

efficiency, temperature coefficient, and durability. Modern high-efficiency monocrystalline

silicon modules often offer the best performance-to-cost ratio for mini-grid applications. The

module's performance under Standard Test Conditions (STC) is typically characterized by:

P_STC = V_OC × I_SC × FF [2.14]

Where P_STC is the module power at STC, V_OC is the open-circuit voltage, I_SC is the

short-circuit current, and FF is the fill factor.

However, it's essential to account for temperature effects on module performance, as

operating temperatures in the field often deviate significantly from STC. The temperature-

corrected power output can be estimated using:

P_actual = P_STC × [1 + γ(T_cell - T_STC)] [2.15]

Where γ is the temperature coefficient of power (typically -0.3% to -0.5% per °C for

crystalline silicon modules), T_cell is the actual cell temperature, and T_STC is 25°C.
60
The configuration of PV modules in strings and arrays must consider voltage and current

limits of the system components, particularly the charge controller or inverter. The number

of modules in series (N_s) and parallel (N_p) can be determined by:

N_s = V_system / V_module [2.16]

N_p = I_required / I_module [2.17]

Where V_system is the system voltage, V_module is the module voltage at maximum power

point, I_required is the required current, and I_module is the module current at maximum

power point.

Shading analysis is another crucial aspect of PV system design. Partial shading can

significantly reduce system output and potentially cause hotspots in modules. Techniques

such as bypass diodes and optimized string configurations can mitigate these effects. The

impact of shading on system performance can be estimated using detailed modeling tools or

simplified approaches like the shading factor method:

E_actual = E_unshaded × (1 - SF) [2.18]

Where E_actual is the actual energy output, E_unshaded is the theoretical unshaded output,

and SF is the shading factor.

The selection and sizing of other system components, including charge controllers, inverters,

and batteries, must be harmonized with the PV array design. For instance, the charge

controller rating should exceed the maximum current and voltage output of the PV array:

I_controller ≥ 1.25 × I_SC_array [2.19]

V_controller ≥ 1.25 × V_OC_array [2.20]

Inverter sizing typically considers both the maximum AC load and the DC input from the PV

array:

P_inverter ≥ max (P_AC_load, P_DC_input) [2.21]

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Battery sizing is crucial for energy storage and system stability. The required battery capacity

can be calculated using:

C_battery = (E_daily × N_autonomy) / (DOD × η_battery × V_battery) [2.22]

Where N_autonomy is the number of autonomy days, DOD is the maximum depth of

discharge, η_battery is the battery efficiency, and V_battery is the battery voltage.

System grounding and protection are essential for safety and reliability. Proper grounding

techniques, surge protection devices, and circuit breakers must be incorporated into the

design. The grounding resistance should typically be less than 5 ohms for mini-grid systems.

Lastly, the physical layout and mounting of PV modules must consider factors such as wind

load, accessibility for maintenance, and optimal tilt angle. The optimal tilt angle (β) for fixed-

tilt systems can be approximated by:

β ≈ |latitude| ± 15° [2.23]

Where the positive sign is used for winter optimization and the negative for summer

optimization in the respective hemispheres.

The design of PV systems for mini-grids requires a holistic approach that integrates various

technical principles and practical considerations. By carefully addressing each aspect of

system design, from energy assessment to component selection and configuration, designers

can create robust, efficient, and sustainable PV systems that effectively serve the energy

needs of rural communities. The principles outlined here provide a foundation for detailed

system design, which must be further refined based on specific site conditions, regulatory

requirements, and economic constraints.

2.7.2 Sizing of PV modules, Inverters, and Batteries

The accurate sizing of photovoltaic (PV) panels, inverters, and batteries is crucial for the

optimal performance and cost-effectiveness of mini-grid systems. This process involves a

62
delicate balance between energy production, conversion, storage, and consumption. The

following discussion provides a comprehensive overview of the sizing methodologies for

these key components.

2.7.2 PV module Sizing:

The sizing of PV modules begins with a thorough assessment of the energy demand and local

solar resource. The required PV array capacity can be determined using the following

equation:

P_PV = (E_d × SF) / (η_system × PSH × PR) [2.24]

Where:

P_PV = Peak power of the PV array (kWp)

E_d = Daily energy demand (kWh/day)

SF = Safety factor (typically 1.1-1.3)

η_system = Overall system efficiency

PSH = Peak Sun Hours (h/day)

PR = Performance Ratio (typically 0.7-0.8)

The number of PV modules (N_modules) required can then be calculated:

N_modules = P_PV / P_module [2.25]

Where P_module is the rated power of a single PV module under Standard Test Conditions

(STC).

It's important to consider the impact of temperature on PV module performance. The

temperature-corrected power output can be estimated using:

P_actual = P_STC × [1 + γ(T_cell - 25°C)] [2.26]

Where γ is the temperature coefficient of power (typically -0.3% to -0.5% per °C for

crystalline silicon modules), and T_cell is the actual cell temperature.

63
2.7.2 Inverter Sizing:

Inverter sizing must account for both the PV array output and the maximum AC load. The

inverter capacity (P_inv) should satisfy:

P_inv ≥ max(P_AC_load, P_DC_input × η_inv) [2.27]

Where:

P_AC_load = Maximum AC load demand

P_DC_input = Maximum DC input from the PV array

η_inv = Inverter efficiency (typically 0.95-0.98)

The DC/AC ratio, which is the ratio of PV array capacity to inverter capacity, is an important

consideration:

DC/AC ratio = P_PV / P_inv [2.28]

Typical DC/AC ratios range from 1.1 to 1.3, allowing for occasional array overproduction

during peak conditions.

For three-phase systems, the inverter capacity should be balanced across phases:

P_inv_phase = P_inv / 3 [2.29]

2.7.2 Battery Sizing:

Battery sizing depends on the required energy storage capacity and system autonomy. The

required battery capacity (C_batt) in ampere-hours (Ah) can be calculated using:

C_batt = (E_d × N_aut) / (DOD × V_batt × η_batt) [2.30]

Where:

N_aut = Number of autonomy days

DOD = Maximum Depth of Discharge (typically 0.5-0.8)

V_batt = Nominal battery voltage

η_batt = Battery round-trip efficiency (typically 0.8-0.9)

64
 The number of batteries in series (N_s) and parallel (N_p) can be determined by:

N_s = V_system / V_batt_nominal [2.31]

N_p = C_batt / C_batt_nominal [2.32]

Where V_system is the system voltage and C_batt_nominal is the capacity of a single battery.

Integrated System Sizing:

The sizing of PV panels, inverters, and batteries must be considered holistically to ensure

system balance and optimal performance. The following constraints should be satisfied:

i. PV array output ≥ (Load demand + Battery charging requirements) / η_system

ii. Inverter capacity ≥ max (PV array output, Maximum AC load)

iii. Battery capacity ≥ (Night-time load + Critical daytime load) × N_aut / DOD

iv. Charge controller rating ≥ 1.25 × I_SC_array (short-circuit current of the array)

Moreover, the system should be designed to minimize energy loss and maximize utilization.

The Loss of Load Probability (LOLP) is a useful metric for assessing system reliability:

LOLP = (Hours of insufficient power supply) / (Total hours in the period) [2.33]

A typical target LOLP for mini-grid systems is less than 0.01 (1%).

The sizing process often involves iteration and optimization, considering factors such as:

i. Seasonal variations in solar resource and load demand

ii. Equipment degradation over time (particularly PV modules and batteries)

iii. Economic factors, including initial investment and lifecycle costs

iv. Local regulations and grid integration requirements (if applicable)

2.7.3 Software Tools for PV System Design and Optimization (e.g., HOMER, PVSyst)

The complexity of designing and optimizing photovoltaic (PV) systems for mini-grids has

led to the development of sophisticated software tools that assist engineers and researchers

in this process. These tools integrate various aspects of system design, including resource
65
assessment, component sizing, performance simulation, and economic analysis. This section

provides a comprehensive overview of the most prominent software tools used in PV system

design and optimization, with a particular focus on HOMER and PVSyst, while also

discussing other relevant tools in the field.

2.7.3.1 HOMER (Hybrid Optimization Model for Multiple Energy Resources):

HOMER, developed by the National Renewable Energy Laboratory (NREL) and now

maintained by HOMER Energy LLC, is one of the most widely used tools for microgrid and

distributed generation power system design and optimization. Its primary strength lies in its

ability to simulate and optimize various system configurations, considering multiple energy

sources and storage options.

Key features of HOMER include:

i. Resource Assessment: HOMER can import or synthesize resource data for solar

radiation, wind speed, and hydro flow rates.

ii. Load Profile Modeling: The software allows for detailed modeling of electric and

thermal loads, including daily and seasonal variations.

iii. Component Modeling: HOMER includes models for various system components,

including PV arrays, wind turbines, generators, batteries, and converters.

iv. Economic Analysis: The tool performs detailed economic calculations, including net

present cost, levelized cost of energy (LCOE), and payback period.

v. Sensitivity Analysis: HOMER can perform sensitivity analyses on various parameters

to assess their impact on system performance and economics.

vi. Optimization: The software uses a proprietary optimization algorithm to determine the

most cost-effective system configuration.

66
Table 2.1: An example of HOMER's optimization output
Rank PV Battery Generator Initial Operating Total LCOE Renewable

(kW) (kWh) (kW) Capital Cost ($/yr) NPC ($) ($/kWh) Fraction

($)

1 100 200 50 250,000 15,000 500,000 0.25 0.75

2 120 180 40 270,000 14,000 510,000 0.26 0.80

3 80 220 60 230,000 16,000 515,000 0.27 0.70

(Babu and Ray, 2023).

2.7.3.2 PVSyst

PVSyst, developed by the University of Geneva, is a software package specifically designed

for the study, sizing, and data analysis of complete PV systems. It is particularly strong in its

detailed modeling of PV system performance and its comprehensive database of PV

components.

Key features of PVSyst includes

i. Preliminary Design: Allows for quick system sizing based on rough input parameters.

ii. Project Design: Provides detailed system design capabilities, including 3D shading

analysis.

iii. Database Management: Includes extensive databases for meteorological data, PV

modules, inverters, and batteries.

iv. Simulation: Performs detailed hourly simulations of system operation.

v. Economic Evaluation: Includes basic economic analysis tools.

vi. Report Generation: Produces comprehensive reports detailing system design and

performance.

PVSyst's strength lies in its detailed modeling of PV system losses, which can be visualized

through its loss diagram:

67
 Figure 3.1: PVSyst's Loss Diagram (André et al., 2024).

2.7.3.3 Comparison of HOMER and PVSyst:

While both tools are valuable for PV system design, they have different strengths.

Table 2.2: Comparison of HOMER and PVSyst

Feature HOMER PVSyst
Scope Hybrid system optimization Detailed PV system analysis
Resource Modeling Flexible, various renewables Primarily solar
Component Database Comprehensive Extensive and regularly updated
Economic Analysis Comprehensive Focused on PV system economics
Optimization Included Limited
Learning Curve Moderate Steep
Babu and Ray, 2023

68
2.7.3.4 Other Relevant Software Tools include:

1. SAM (System Advisor Model): Developed by NREL, SAM combines detailed

performance modeling with financial analysis for various renewable energy technologies.

2. RETScreen: Developed by Natural Resources Canada, RETScreen is a clean energy

management software suite for energy efficiency, renewable energy, and cogeneration

project feasibility analysis.

3. PVSOL: A German software that offers 3D visualization and detailed shading analysis

for PV systems.

4. Polysun: A Swiss software that specializes in the simulation of solar thermal, PV, and

heat pump systems.

5. TRNSYS: A flexible tool that allows for the simulation of transient systems, including

solar energy systems.

Table 2.3: Comparative analysis of HOMER, PVSyst, SAM, RETScreen, PVSOL,

Polysun, and TRNSYS
Feature HOMER PVSyst SAM RETScreen PVSOL Polysun TRNSYS

PV Modeling ✓ ✓✓ ✓✓ ✓ ✓✓ ✓ ✓

Hybrid Systems ✓✓ ✗ ✓ ✓ ✗ ✓ ✓✓

Economic Analysis ✓✓ ✓ ✓✓ ✓✓ ✓ ✓ ✓

Optimization ✓✓ ✗ ✓ ✗ ✗ ✗ ✗

3D Shading ✗ ✓✓ ✓ ✗ ✓✓ ✓ ✗

Component Database ✓ ✓✓ ✓✓ ✓ ✓✓ ✓ ✓

Flexibility ✓ ✓ ✓ ✓ ✓ ✓ ✓✓

✓✓: Excellent, ✓: Good, ✗: Limited or Not Available

André et al., 2024

69
 The comparison of various solar energy modeling software reveals distinct strengths and

capabilities across different programs. While all the evaluated software can perform PV

modeling, PVSyst and SAM stand out as particularly proficient in this area. For hybrid

system modeling, HOMER, SAM, and TRNSYS offer robust capabilities, whereas PVSyst,

PVSOL, and Polysun are not designed for this purpose. In terms of economic analysis,

HOMER, SAM, and RETScreen provide superior tools, though the other programs also offer

good economic assessment features. Notably, only HOMER and SAM include optimization

functionalities, setting them apart in system design optimization. When it comes to 3D

shading analysis, PVSyst, PVSOL, and Polysun are the sole options among the compared

software. All programs maintain component databases, but PVSyst and SAM boast the most

comprehensive and current collections. Lastly, while each software demonstrates a degree of

flexibility, TRNSYS emerges as the most adaptable tool in the group, allowing for a wide

range of customization and application scenarios. These observations highlight the diverse

strengths of each software, emphasizing the importance of choosing the right tool based on

specific project requirements and modeling needs.

2.7.3.4 Best Practices for Using PV System Design and optimization software

i. Data Quality: Ensure high-quality input data, particularly for solar resource and load

profiles.

ii. Validation: Cross-validate results using multiple tools or manual calculations when

possible.

iii. Sensitivity Analysis: Perform comprehensive sensitivity analyses to understand the

impact of various parameters on system performance and economics.

iv. Component Selection: Use up-to-date component databases and verify specifications

with manufacturers.
70
 v. Site-Specific Factors: Consider site-specific factors such as shading, soiling, and local

regulations that may not be fully captured by the software.

vi. Continuous Learning: Stay updated with software updates and new features, as these tools

are continually evolving.

vii. Integration with Other Tools: Consider integrating results with GIS tools for spatial

analysis or financial modeling software for more detailed economic assessments.

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 CHAPTER THREE

3.0 RESEARCH METHODOLOGY AND SYSTEM DESIGN

3.1 Research Design

The research design for this study follows a systematic approach to developing a standalone

PV-based mini-grid system for the Dota Community. This process is structured into four

distinct phases, each building upon the previous to ensure a comprehensive and effective

design. The flow chart below (Figure 3.1) illustrates the sequential steps taken from initial

site assessment through to final system detailing, providing a clear roadmap for the entire

project.

72
Figure 3.1: Research design for standalone PV-based Mini-grid design for Dota
Community.
3.2 Community visit and Energy Demand Assessment

The foundation of an effective photovoltaic mini-grid system will lie in a comprehensive

understanding of the site conditions and energy requirements. This section will detail the

methodologies to be employed to gather and analyze crucial data for informed system design.

3.2.1 Community Survey

To accurately assess the energy needs and preferences of the target community, a mixed-

method approach combining quantitative and qualitative data collection will be adopted.

Household/business surveys will be carried out, the survey will be administered to all

household/business in the community representing 100% of the sample size as it is a small

73
community and to ensure accurate data capturing of appliance ownership, energy usage

patterns, and socio-economic characteristics. To ensure cultural sensitivity and maximize

participation, local enumerators will be trained to administer the surveys and conduct

interviews in the local language. This approach will not only enhance the quality of responses

but also foster community engagement in the project. Enumerators will be required to visit

households and businesses to administer the survey and observe appliances directly, power

ratings of appliances will be verified using a portable wattmeter where possible.

3.2.2 Load Assessment Technique

A rigorous load assessment will be carried out to quantify the community's energy demand

accurately. This process will involve a combination of direct measurements and estimation

techniques:

i. A comprehensive inventory of electrical appliances used in households, businesses,

and public facilities will be compiled. This will include detailed information on the

wattage of each appliance and its typical usage duration.

ii. Power ratings of electrical appliances will be verified by physical observation of

nameplate and using a portable wattmeter where possible.

iii. Using the data from the electrical appliance inventories, detailed load profiles will be

developed for different categories of consumers (e.g., residential, commercial, public

services). These profiles will be crucial for understanding the temporal distribution of

energy demand throughout the day and across seasons.

iv. To avoid overestimation of the system capacity, diversity factors will be calculated to

account for the non-simultaneous operation of all appliances. This analysis will

consider the usage patterns of different consumer categories and their impact on the

overall load.
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 3.2.3 Geographical Survey

A comprehensive geographical survey will be conducted to assess the suitability of the site

for PV installation and to inform the mini-grid layout design. It will also give information on

availability of potential installation site for the mini-grid. The following procedures will be

implemented:

i. High-resolution satellite imagery and digital elevation models will be obtained from the

Federal Capital Development Agency (FCDA). These data will be processed using

Geographic Information System (GIS) software to create detailed topographical maps of

the area, highlighting elevation changes and potential obstacles.

ii. A team of surveyors will conduct on-site assessments to verify and supplement the

satellite data. This will include detailed measurements of available land areas,

identification of natural and man-made obstacles, and assessment of soil conditions for

foundation work.

iii. Using specialized solar pathfinder equipment, a comprehensive shading analysis will be

performed across potential installation sites. This analysis will account for existing

structures and vegetation, as well as potential future developments that could impact solar

exposure.

iv. The team will assess road conditions, terrain navigability, and proximity to existing

infrastructure to determine the feasibility of equipment transportation and ongoing

maintenance access.

v. Existing electrical infrastructure, water sources, and communal facilities will be mapped

to inform the mini-grid distribution network design and identify potential synergies or

constraints.

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 3.2.4 Solar Resource Assessment

Accurate solar resource assessment will be paramount for the successful design and operation

of a photovoltaic mini-grid. A multi-faceted approach will be employed to gather

comprehensive solar radiation data:

i. Long-term solar irradiance data will be obtained from the Nigerian Meteorological

Agency (NIMET). This dataset, spanning the past 20 years, will provide valuable insights

into seasonal variations and long-term trends in solar resource availability.

ii. To complement ground-based measurements, satellite-derived solar radiation data will

be acquired from reputable sources such as NASA's Surface Meteorology and Solar

Energy database. These data will offer broader spatial coverage and help fill gaps in

ground-based observations.

iii. In addition to solar radiation, other relevant climate data including temperature, humidity,

wind speed, and precipitation will be collected. These parameters will be crucial for

estimating PV module performance and potential environmental stressors.

3.3.1 System Components Selection Criteria

3.3.1.1 Photovoltaic Modules

The selection of photovoltaic modules will be based on the following criteria:

i. Modules with conversion efficiencies exceeding 20% will be prioritized to maximize

energy production within the available space.

ii. Given the high ambient temperatures in the region, modules with temperature coefficients

below -0.35%/°C will be favored.

iii. Modules with IEC 61215 certification for reliability and IEC 61730 certification for

safety will be selected.

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iv. Modules offering warranties of 25 years or more and annual degradation rates below 0.5%

will be preferred.

3.3.1.2 Battery Storage

The battery storage system selection criteria will include:

i. Lithium iron phosphate (LFP) batteries will be primarily considered due to their balance

of performance, safety, high energy density and longer life span.

ii. Batteries with a cycle life of at least 4000 cycles at 80% depth of discharge will be favored.

iii. The system will be designed for a maximum depth of discharge of 80% to balance battery

life and system economics.

iv. Round-trip efficiency of 95% or higher will be prioritized.

v. Batteries capable of operating in temperatures up to 50°C without significant degradation

will be selected.

vi. Modular battery systems that allow for easy capacity expansion will be preferred.

3.3.1.3 Inverters and Charge Controllers

The selection criteria for inverters and charge controllers will include:
i. Pure sine wave inverters will be prioritized to ensure high-quality power output

suitable for all load types.

ii. Low-frequency transformer-based inverters will be prioritized due to their efficiency

in handling inductive loads, crucial for supporting small-scale industries and motor-

driven appliances in the community. For larger system capacities exceeding 10 kW,

three-phase inverters will be considered to balance loads and improve system

stability.

iii. Inverters with peak efficiencies above 98% and CEC weighted efficiencies above
97% will be considered.

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iv. Maximum Power Point Tracking (MPPT) charge controllers will be mandatory to

optimize PV array output under varying conditions. Support for various battery

chemistries is essential, with specific focus on compatibility with the selected

Lithium Iron Phosphate (LFP) batteries. Multi-stage charging algorithms with

temperature compensation will be required for optimal battery management.

v. Preference will be given to manufacturers with a proven track record in mini-grid

applications, particularly in similar climatic conditions. The availability of local

technical support and spare parts is crucial to minimize system downtime. Warranty

terms should be at least 5 years for both inverters and charge controllers, with options

for extended warranties.

3.3.2 System Sizing and Calculations

The system sizing process will involve detailed calculations based on the energy demand

analysis and solar resource assessment. The following methodologies will be employed:

3.3.2.1 PV Array Sizing

The PV array sizing will be conducted using the following steps and calculations:

Energy Requirement Calculation:

𝐃𝐚𝐢𝐥𝐲 𝐥𝐨𝐚𝐝
Daily energy requirement = (𝛈_𝐢𝐧𝐯𝐞𝐫𝐭𝐞𝐫 × 𝛈_𝐌𝐏𝐏𝐓 × 𝛈_𝐛𝐚𝐭𝐭𝐞𝐫𝐲) [3.1]

Where:

Daily load is determined from the load assessment

η_inverter is the inverter efficiency (typically 0.95-0.98)

η_MPPT is the MPPT efficiency (typically 0.98-0.99)

η_battery is the battery round-trip efficiency (typically 0.85-0.95 for lithium-ion)

Peak Sun Hours Determination:

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Peak Sun Hours (PSH) will be calculated from the solar resource assessment data,

representing the number of hours per day when solar irradiance averages 1 kW/m². The PSH

can be calculated using the following equation:

𝐃𝐚𝐢𝐥𝐲 𝐆𝐥𝐨𝐛𝐚𝐥 𝐇𝐨𝐫𝐢𝐳𝐨𝐧𝐭𝐚𝐥 𝐈𝐫𝐫𝐚𝐝𝐢𝐚𝐭𝐢𝐨𝐧 (𝐤𝐖𝐡/𝐦²)

PSH = [3.2]
𝟏 𝐤𝐖/𝐦²

This calculation will be performed for each month, and the lowest monthly average will

typically be used for system sizing to ensure year-round reliability.

Array Capacity Calculation:

𝐃𝐚𝐢𝐥𝐲 𝐞𝐧𝐞𝐫𝐠𝐲 𝐫𝐞𝐪𝐮𝐢𝐫𝐞𝐝

PV array size (kWp) = (𝐏𝐒𝐇 × 𝐏𝐞𝐫𝐟𝐨𝐫𝐦𝐚𝐧𝐜𝐞 𝐑𝐚𝐭𝐢𝐨) [3.3]

Where: Performance Ratio accounts for various system losses and is typically 0.75-0.85 for

well-designed systems.

Module Selection and Array Configuration:

𝐏𝐕 𝐚𝐫𝐫𝐚𝐲 𝐬𝐢𝐳𝐞 (𝐤𝐖𝐩)

Number of modules = 𝐑𝐚𝐭𝐞𝐝 𝐩𝐨𝐰𝐞𝐫 𝐨𝐟 𝐬𝐞𝐥𝐞𝐜𝐭𝐞𝐝 𝐦𝐨𝐝𝐮𝐥𝐞 (𝐤𝐖𝐩) [3.4]

The series-parallel configuration will be determined based on the inverter specifications and

system voltage requirements.

3.3.2.2 Battery Capacity Calculation

The battery storage capacity will be sized using the following methodology:

Capacity Calculation:

(𝐃𝐚𝐲𝐬 𝐨𝐟 𝐀𝐮𝐭𝐨𝐧𝐨𝐦𝐲 × 𝐃𝐚𝐢𝐥𝐲 𝐥𝐨𝐚𝐝)

C_B = [3.5]
(𝑫𝒐𝑫×𝑽_𝒔𝒚𝒔×𝛈_𝐛𝐚𝐭𝐭𝐞𝐫𝐲)

Where:

C_B is the required battery capacity in Ah

Days of Autonomy will be determined based on local weather patterns, typically 2-3 days

DoD is the maximum allowable depth of discharge (e.g., 0.8 for 80% DoD)

79
V_sys is the system voltage

η_battery is the battery efficiency

Temperature Derating:

The calculated capacity will be increased by a factor of 1.2 to account for performance

reduction in high temperatures.

Future Load Growth:

An additional 20% capacity will be added to accommodate projected load growth over the

system's lifetime.

Battery Configuration:
𝐕_𝐬𝐲𝐬
Number of batteries in series (N_s) =𝐕_𝐛𝐚𝐭𝐭𝐞𝐫𝐲 [3.6]

𝐂_𝐁
Number of batteries in parallel (N_p) = (𝐍_𝐬 × 𝐂_𝐛𝐚𝐭𝐭𝐞𝐫𝐲) [3.7]

Where:

V_battery is the nominal voltage of a single battery

C_battery is the capacity of a single battery

3.3.2.3 Inverter and Charge Controller Sizing

The inverter and charge controller sizing will ensure efficient power conversion and system

protection:

Inverter Sizing:

Inverter capacity = 𝐏𝐞𝐚𝐤 𝐥𝐨𝐚𝐝 × 𝟏. 𝟐𝟓 (𝐬𝐚𝐟𝐞𝐭𝐲 𝐟𝐚𝐜𝐭𝐨𝐫) [3.8]

The inverter will be sized to handle the peak load with a 25% safety factor to account for

surge requirements.

Charge Controller Sizing:

(𝐏𝐕 𝐚𝐫𝐫𝐚𝐲 𝐩𝐞𝐚𝐤 𝐩𝐨𝐰𝐞𝐫 × 𝟏.𝟐𝟓)

Charge controller current = [3.9]
𝐕_𝐬𝐲𝐬

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The charge controller will be sized to handle 125% of the maximum potential current from

the PV array to account for irradiance spikes.

System Voltage Consideration:

The system voltage will be selected based on the total power capacity:

< 5 kW: 24V or 48V

5-20 kW: 48V or 96V

20 kW: 240V or higher

3.3.2.4 Days of Autonomy Calculation

(𝐁𝐚𝐭𝐭𝐞𝐫𝐲 𝐂𝐚𝐩𝐚𝐜𝐢𝐭𝐲 × 𝐃𝐨𝐃 × 𝐒𝐲𝐬𝐭𝐞𝐦 𝐕𝐨𝐥𝐭𝐚𝐠𝐞)

Days of Autonomy = [3.10]
(𝐃𝐚𝐢𝐥𝐲 𝐄𝐧𝐞𝐫𝐠𝐲 𝐂𝐨𝐧𝐬𝐮𝐦𝐩𝐭𝐢𝐨𝐧)

Where:

Battery Capacity is in Ampere-hours (Ah)

DoD is the depth of discharge (as a decimal)

System Voltage is in Volts (V)

Daily Energy Consumption is in Watt-hours (Wh)

Applying a safety factor:

Adjusted Days of Autonomy = Calculated Days of Autonomy × Safety Factor [3.11]

3.4. System Configuration Optimization

Advanced simulation and optimization techniques will be employed using HOMER Pro

software to ensure the most cost-effective and reliable system design.

3.4.1 HOMER Pro Simulation Setup

The HOMER Pro model setup will include:

3.4.1.1 Load Profile Integration

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Import hourly load profiles developed during the energy demand analysis and create seasonal

load variations based on survey data

3.4.1.2 Resource Data Input:

Import hourly solar irradiance data for a typical meteorological year and input temperature

profiles and other relevant environmental data.

3.4.1.3 Component Library Creation:

Define PV module characteristics (power rating, efficiency, and temperature coefficients),

input battery specifications (capacity, DoD, cycle life, efficiency) and set inverter and charge

controller parameters (capacity, efficiency curves).

3.4.2 Input Parameters and Constraints

The simulation will be configured with various input parameters and constraints:

i. Technical Constraints:

a. Minimum renewable fraction: 95%

b. Maximum capacity shortage: 5%

c. Operating reserve: 10% of hourly load, 25% of solar power output

ii. Economic Parameters:

a. Project lifetime: 25 years

b. Discount rate: 8%

c. Inflation rate: 2%

iii. Sensitivity Variables:

a. Load growth: 0%, 2%, 5% annually

b. PV module cost

c. Battery cost

3.4.3 Optimization Criteria

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The optimization process will employ a multi-objective approach to identify the system

configuration that best meets the project objectives while ensuring economic viability,

technical feasibility, and environmental sustainability. The following criteria and parameters

will be considered:

3.4.3.1 Economic Viability

i) Levelized Cost of Energy (LCOE):

The LCOE will be calculated using the following equation:

(𝐓𝐨𝐭𝐚𝐥 𝐍𝐞𝐭 𝐏𝐫𝐞𝐬𝐞𝐧𝐭 𝐂𝐨𝐬𝐭)

LCOE = [3.12]
(𝐓𝐨𝐭𝐚𝐥 𝐄𝐧𝐞𝐫𝐠𝐲 𝐒𝐞𝐫𝐯𝐞𝐝)

Where:

Total Net Present Cost includes initial capital expenditure, operational and maintenance costs,

and replacement costs over the project lifetime, discounted to present value.

Total Energy Served is the sum of all energy output over the project lifetime, discounted at

the same rate.

The optimization will prioritize configurations with the lowest LCOE while meeting

reliability and other constraints. A target LCOE of less than $0.30/kWh will be set to ensure

competitiveness with alternative energy sources.

ii) Net Present Value (NPV) and Internal Rate of Return (IRR):

The NPV and IRR of the project will be calculated to assess its financial viability:

NPV = Σ (Ct / (1+r) t) - C0 [3.13]

Where:

Ct is the net cash inflow during the period t

C0 is the total initial investment cost

r is the discount rate

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t is the number of time periods

The IRR will be calculated as the discount rate that makes the NPV of the project equal to

zero. A positive NPV and an IRR exceeding the weighted average cost of capital (WACC)

by at least 3% will be required for economic viability.

iii) Payback Period:

The discounted payback period will be calculated to determine the time required to recover

the initial investment. A maximum payback period of 7 years will be set as a constraint.

3.4.3.2 Reliability Metrics

i. Loss of Load Probability (LOLP):

LOLP = (Total hours of outage) / (Total hours in study period) [58]

The system will be designed to achieve an LOLP of less than 1%.

ii. System Average Interruption Duration Index (SAIDI)

(𝐒𝐮𝐦 𝐨𝐟 𝐚𝐥𝐥 𝐜𝐮𝐬𝐭𝐨𝐦𝐞𝐫 𝐢𝐧𝐭𝐞𝐫𝐫𝐮𝐩𝐭𝐢𝐨𝐧 𝐝𝐮𝐫𝐚𝐭𝐢𝐨𝐧𝐬)

SAIDI = [3.14]
(𝐓𝐨𝐭𝐚𝐥 𝐧𝐮𝐦𝐛𝐞𝐫 𝐨𝐟 𝐜𝐮𝐬𝐭𝐨𝐦𝐞𝐫𝐬 𝐬𝐞𝐫𝐯𝐞𝐝)

A target SAIDI of less than 8 hours/year will be set to ensure high reliability.

iii. Capacity Shortage Fraction:

(𝐄𝐧𝐞𝐫𝐠𝐲 𝐝𝐞𝐦𝐚𝐧𝐝 𝐧𝐨𝐭 𝐦𝐞𝐭)

CSF = [3.15]
(𝐓𝐨𝐭𝐚𝐥 𝐞𝐧𝐞𝐫𝐠𝐲 𝐝𝐞𝐦𝐚𝐧𝐝)

The optimization will aim for a CSF of less than 0.5% to ensure adequate system capacity.

3.4.3.3 Environmental Impact

i. CO2 Emissions Reduction:

The annual CO2 emissions reduction will be calculated compared to a diesel generator

baseline:

CO2 Reduction = (Baseline emissions) - (PV system emissions) [3.15]

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A minimum reduction of 80% compared to the diesel baseline will be targeted.

ii. Life Cycle Assessment (LCA):

A comprehensive LCA will be conducted to assess the environmental impact of the system

over its entire lifecycle, including manufacturing, transportation, operation, and end-of-life

disposal.

3.4.3.4 Scalability and Flexibility

i. Modular Expansion Capability:

The optimization will favor configurations that allow for modular expansion to accommodate

future load growth. A scalability factor (SF) will be introduced:

(𝐌𝐚𝐱𝐢𝐦𝐮𝐦 𝐞𝐱𝐩𝐚𝐧𝐬𝐢𝐨𝐧 𝐜𝐚𝐩𝐚𝐜𝐢𝐭𝐲)

SF = [3.16]
(𝐈𝐧𝐢𝐭𝐢𝐚𝐥 𝐜𝐚𝐩𝐚𝐜𝐢𝐭𝐲)

A minimum SF of 1.5 will be set to ensure adequate expansion potential.

ii. Demand Response Integration:

The system's ability to integrate demand response mechanisms will be evaluated and factored

into the optimization process.

3.5 Distribution Network Design

i. Network topology: A radial distribution system with the possibility of creating loops

for increased reliability will be considered.

ii. System voltage: Low voltage distribution at 230/415V will be implemented, with the

potential for medium voltage (11kV or 33kV) integration for future expansion.

iii. Voltage drop: Maximum voltage drop shall not exceed 5% from the source to the

farthest load point.

3.6 Detailed System Specification

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After system sizing, configuration and optimization, a detailed system specification will be

which includes cable sizing, tilt angle and orientation of PV array, system protection as well

as implementation guidelines for installation of the mini-grid will be done.

3.6.1 Balance of System Components:

i. Cable sizing to limit power losses to less than 3% of total generation

ii. Protection systems including surge arresters, circuit breakers, and grounding design

iii. Monitoring and control systems with remote access capabilities

3.6.2 PV Array

i. Tilt angle optimization based on latitude and seasonal variation

ii. Inter-row spacing to minimize shading (Ground Coverage Ratio optimization)

3.6.3 Battery storage

i. Depth of Discharge (DoD) limit of 80% to balance between capacity utilization and

battery lifespan

ii. Temperature management system to maintain optimal operating conditions

3.6.4 Implementation Guidelines

i. Installation procedures adhering to IEC 62548 for PV array installation

ii. Commissioning protocols including performance ratio verification

iii. Operations and maintenance schedules with defined key performance indicators

(KPIs)

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