Renewable and Sustainable Energy Reviews xxx (xxxx) xxx–xxx

Contents lists available at ScienceDirect

Renewable and Sustainable Energy Reviews

journal homepage: www.elsevier.com/locate/rser

Global modern monitoring systems for PV based power generation: A review

⁎
M.Mahbubur Rahmana,b, J. Selvaraja, , N.A. Rahima, M. Hasanuzzamana
a
UM Power Energy Dedicated Advanced Centre (UMPEDAC), Level 4, Wisma R&D, University of Malaya, Jalan Pantai Baharu, 59990 Kuala Lumpur, Malaysia
b
Institute of Graduate Studies, University of Malaya, 50603 Kuala Lumpur, Malaysia

A R T I C L E I N F O A B S T R A C T

Keywords: Photovoltaic system is widely installed to increase the share of renewable energy as well as to reduce the
Solar energy environmental impact of fossil fuel based energy. Photovoltaic (PV) is one of the most potential renewable
Photovoltaic energy based power generation systems. Monitoring of PV system is very important to send information that
Monitoring system allows owners to maintain, operate and control these systems to reduce maintenance costs and to avoid un-
Internet based monitoring
wanted electric power disruptions. Different monitoring systems have been introduced with the time following
Circuit complexity
different requirements. Circuit complexity, availability of friendly graphical user interface, easy to understand
Low-cost
system architecture, maintenance facility and customization ability for end user differ from system to system
along with cost issues. This paper provides an overview of architectures and features of various PV monitoring
systems based on different methods. There are various technologies for PV monitoring and control, developed as
for commercial use or research tasks. It has been seen that a large portion of the work is done on classifications,
for example, Internet based Monitoring using Servers, TCP/IP, GPRS and so forth. There are various meth-
odologies for data acquisition, for example, PLC (Power Line Communication), PIC, Reference cell, National
Instruments etc. Various requirements are considered while selecting a proper monitoring system for an ap-
plication. Review of various monitoring technologies with system attributes and working structures have been
discussed to get a clear view of merits and demerits of existing PV monitoring systems. All the systems discussed
in this paper have pros and cons, and these systems were developed following different requirements. In the end,
a particular cost effective monitoring system using Arduino microcontroller has been proposed considering both
research and user level requirements from perspectives of cost, availability of parts/modules and features,
compatibility with sensors and end-devices etc.

1. Introduction flaws. New technologies are enhancing PV power generation with time.
There are many varieties of PV panels following different manu-
Photovoltaic system is widely installed in residential sectors these facturing processes. In the research field, to test the performance and to
days to increase the share of renewable energy as well as to reduce detect any unwanted defect of installed panels, the monitoring system
environmental impact of fossil fuel based energy. But, in most of the can place a significant influence. A monitoring system can be pre-
cases, monitoring is not done properly, neither is the maintenance. defined for a specific purpose or several parameters monitoring. Thus it
Subsequently, a PV monitoring device needs to give both point-by-point can support demand side management as well, for both research and
checking of each PV module and an easy to understand method for user level entities. PV system generates power for a certain period
access to the observed information. Besides, the PV monitoring system during daylight. On the other hand, peak hours for energy consumption
should be low-cost to be broadly accepted. for a particular sector can be either day time (i.e. office/factory) or
Since solar energy has turned out to be popular as a stable renew- night time (i.e. residential). For large industrial/official sector or small
able energy source, measuring real time data of system after installation residential sector, load consumption data can be measured and com-
has become a noteworthy concern. As for scientific research work or pared alongside monitoring system data of PV power generation. Such
user level benefit, different reasons can affect a system's power gen- comparison of power generation output data and load consumption can
eration, for example, faulty wiring, PV panel output abnormalities, provide a clear view of supply/generation and demand side require-
environmental issues (i.e. temperature, solar irradiation, humidity etc.), ment. It is quite improper to declare if a PV system is running appro-
faulty inverter, unexpected damage and also common manufacturing priately or not just by viewing the system architecture. Without a

⁎
Corresponding author.
E-mail address: jeyraj@um.edu.my (J. Selvaraj).

https://doi.org/10.1016/j.rser.2017.10.111
Received 1 November 2016; Received in revised form 30 July 2017; Accepted 30 October 2017
1364-0321/ © 2017 Elsevier Ltd. All rights reserved.

Please cite this article as: Rahman, M.M., Renewable and Sustainable Energy Reviews (2017), http://dx.doi.org/10.1016/j.rser.2017.10.111
M.M. Rahman et al. Renewable and Sustainable Energy Reviews xxx (xxxx) xxx–xxx

Nomenclature CRC Cyclic Redundancy Check

ADC Analog to Digital Converter
TCP/IP Transmission Control Protocol/Internet Protocol DDDM Data-Driven Decision-Making
LwIP Lightweight Internet Protocol RTAI Real Time Application Interface
HMI Human Machine Interface PB Profit Balance/Balance of Profit
ACU Acquisition-Control Unit BOS Balance of System
MIC Module Interconnection Circuit IP Initial Profit
CSMA Carrier Sense Multiple Access

monitoring system, the only method to ensure its activity is to observe performance measuring but, expensive for residential PV owners [8].
meter-reading or the inverter display. It is considered suitable and fi- Power-Line Communication system can be cheaper in a sense but, im-
nancially efficient to own a monitoring system with real-time data poses interference issue with other electronics devices [1]. Module-to-
monitoring that can be accessed from anywhere. Module System, Referenced Cell Based monitoring system or Peripheral
PV power generation monitoring reduces expense by providing in- Interface Controller is good for research purposes, though these are
formation on solar power system. For instance, the monitoring system difficult to implement and to keep up with maintenance for residential
assists to detect any flaw in the PV system, so the owner can move PV owners [9–11]. ARM Cotex-M3 Processor Based System is suitable
effectively and initiate proper care when needed. Otherwise, it may for factory with large power plant and grid connected PV system since it
turn into an economic issue. PV system monitoring also makes it pos- is capable of managing huge amount of data, and can be helpful to
sible to compare power output from PV system with billing information. process data from other equipment of the factory as well [12–14]. But
Even if the PV monitoring system is not checked regularly, it will send such monitoring systems are also very complicated to work with. These
an alert whenever there is a predefined event that requires owner's systems require expert brain to deal with maintenance issue as well.
concern. Monitoring for PV can be utilized at two levels which are, Since the monitoring system for PV installation is a vital aspect related
panel level and system level. Monitoring at system level gives in- to PV system's efficiency, it is necessary to have an idea regarding ex-
formation about how the PV system is working as a complete unit. On isting systems and their technologies before approaching a different
the other hand, monitoring at panel level provides information on each monitoring system development.
panel performance. Panel level monitoring enables to identify problems The aim of the paper is to have an overview of different monitoring
related to PV system more accurately. This attribute improves the systems used or proposed for PV installations around the world focusing
economic factor of PV system. Most of the time, Private PV systems are on monitoring important parameters following consumers demand as
not being checked or oversaw. Only PV inverter information is not well as researchers’ aspects, also to review the communication tech-
enough to get a clear view of system status. Every connected module nologies used for different monitoring systems, to provide possible
influences the power production concerning the entire PV system fol- notes on pros and cons of the systems, and lastly to propose an alter-
lowing the fact that the production relies on output from every attached native solution to meet all basic requirements of monitoring system for
module. A faulty module corrupts the production of the entire output of PV installation in easy manner. Availability of different technologies
PV. This is why monitoring of every PV module is important to keep up throughout time inspired researchers to use various methods to acquire
the performance of the PV system. Furthermore, an easy to understand PV system related data. Development of monitoring system architecture
user interface is more important to give a simple method for access to and mechanism have been discussed along with performance in this
the recorded information [1]. paper.
Monitoring electrical and weather information arise from the need
of evaluating profitability and functioning settings. Both atmospheric
2. Different monitoring systems
and electrical elements have an impact on the efficiency of power
generation. PV modules are sensitive to environmental variables, to be
There are various types of commercial system to monitor both small
specific irradiance and temperature. The information of electric data,
and large grid-connected PV installations. Many companies distribute
waveform logs, occurrences, weather information, etc. are considered
commercial solutions for monitoring PV systems like Fat Spaniel
important for analyzing PV output [2]. Financial specialists choose to
Technologies, SMA Solar Technologies, in Access Networks,
use cash on PV power production following PB (Profit Balance/Balance
Morningstar Corporation, Fronius International GmbH or SolarMax.
of Profit) and IP (Initial Profit) premise which are very important facts
Their solutions usually provide Software as a Service (SaaS) that offers
to perceive exceptionally well Igm and BOS. Balance of System (BOS)
its functionality as a web-based service [15–18]. Such web application
relies upon a few variables like cable loss (AC-DC output), heat impacts,
allows final users to view transient phenomena and historical data of PV
efficiency of the system, setup of the system (series or parallel design),
output. Additionally, some advanced applications distribute more va-
etc. [3]. Wind speed, irradiation, temperature of the module and vol-
luable services, such as alarms or notifications (e.g., e-mails or text
tage-current output of PV system, etc. are being used for anticipating
messages) when issues like breakdowns or specific operating conditions
and displaying of meteorological information and photovoltaic system
arise. However, commercial solutions present some drawbacks [19,20].
output [4].
Data measuring and recording devices consume too much energy. They
To select a solution for specific demand of time/situation, Linux,
also require high storage for defined states of information recording.
Reference Based Cell, even satellite has been used. Satellite based
Commercial software does not meet requirements properly for every
monitoring system certainly imposes a cost issue, but it is the best so-
installation because new functionalities cannot be added to them from
lution for remote monitoring in areas where no wired/wireless network
the user end, for example, personalized performance assessments or
is available [5]. Linux Real Time Application Interfaced device was
production forecasts.
developed for easier implementation with MATLAB and Simulink for a
A proper monitoring system has several stages. It requires wireless
thorough analysis of recorded data. This process requires extensive
or wired sensors to record environmental measurements as well as
knowledge on Linux OS to make it work with data analysis software like
electrical and physical parameters for various accessories of PV system.
MATLAB, as well as hardware/external sensors [6]. ZigBee technology
Recorded information from electronic devices and sensors are stored in
offers wireless transmission of data, yet susceptible to obstacle and
Data Logger and then transferred to owners (e.g. Computer/Smart
range limitation [7]. National Instruments are satisfactory for
Devices/Website). A Huge amount of data is gathered by sensors. This

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information has to be processed, stored and then published as a periodic

report for easy-understanding.
According to modern architecture, a monitoring system's workflow
can be divided into three stages as shown in Fig. 1 ‘Acquisition Layer’,
‘Pretreatment and Record Layer’ and ‘Storage, Supervision and Access
Layer’.

• The Acquisition Layer has different sensors for obtaining predefined

signals from PV panel and environmental variables. There are sev-
eral hardware platforms available for wireless sensor network de-
ployments such as XBee, TelosB, Mica, IRIS and Waspmote. These
wired or wireless connections to these end devices form a network
using Bluetooth, Wifi, RF transmission or Wire and send gathered
information to Pretreatment and Record stage.
• Pretreatment and Record Layer regulates the data received from the
sensor network. Collected information is temporarily saved into a
buffer of microcontroller, data logger or workstation for data-man-
agement (e.g. MySQL, Linux, etc.) and then transferred to the Fig. 2. Software flowchart diagram using single CPU [2].
Supervision and Storage Layer at predefined intervals using wired or
wireless connection (e.g. router).
• Finally, Supervision and Storage Layer manages the obtained data measurements (current, voltage, power), weather information (tem-
perature, irradiance), performance of the PV system, performance of
from data logger in local storage or cloud server and publish the
data on local monitoring device (e.g. monitoring screen, computer, the inverter over various working phenomena. The system transferred
workstation, smart devices) or on the Internet. This Layer offers a data through TCP-IP system for downloading information and to ob-
graphical user interface or web interface to manage and display serve working status [2]. The proposed system prototype was config-
acquired information and also to generate statistics for the end ured using MATLAB and Simulink, compiled using Real Time Workshop
users. toward RTAI focus [21]. The prototype consisted of signal computation
functions and constant control, real-time data detection and recording.
Several works have been done focusing on monitoring system so far. In tests, the working device used GNU/Linux scripts in using Scratch
Some significant systems have been discussed in this section. These Project 6.3 [22]. Recorded information was repeatedly replaced to save
systems are based on different approach using different methods and space in the data logger.
communication technologies. For all the monitoring systems, the basic The monitoring device follows RTAI utilizing functions through lxrt
workflow is primarily similar. They all follow the basic monitoring expansion module. Data were measured using digital and analog sen-
system architecture described earlier to meet the end target of mon- sors following standard protocols. Few of these data (VA, IA, VU, Gi, Ii,
itoring which includes data acquisition, processing and supervision. Tam, Tm) were accessible from the optimized hardware appeared in
The following monitoring systems have been designed using different Fig. 2. Recorded data is then transferred to be analyzed and shared. To
methods to meet required criteria of PV system monitoring. The dis- work with such system, it requires having better knowledge on Linux as
cussion is focused on different approaches to acquire data from PV well as on MATLAB & Simulink for signal computation functions and
system, different communication technologies of the existing systems other tasks.
and different technologies/electronic devices used for data monitoring
system. 2.2. ZigBee radio technology

Andreoni proposed wireless monitoring as well as control arrange-

2.1. Linux Real Time Application Interface (RTAI) ment of PV-DG (Photovoltaic Distributed Generator) for microgrid
using ZigBee [7]. ZigBee module can create network by itself in case of
Linux Real Time Application Interface based device was introduced any transceiver gets disconnected. ZigBee system consists of two parts,
by Chaindone targeting at detection, record and transmission of Full Function Device (FFD) and Reduced Function Device (RFD). FFD
weather and electrical data from a PV plant [6]. Acquired data from works for setting up addressing plan, to keep the location tables and it is
inverter and PV array through proper sensors were electrical the main system component for connecting with other modules. FFD

Fig. 1. Basic architecture of monitoring system.

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can forward information, find neighboring devices and develop paths to topologies depending on its use [28].
different hubs. The RFD only connects itself to a nearby network. The Hu, Yujie showed architecture using ZigBee WSN and GPRS [27].
module typically awakes when it needs to receive or transmit data. Set The wireless modules need low energy utilization for information
of specific sensors for monitoring as well as to save status is defined as a transfer [27]. ZigBee is capable of working in various types of grid-
sensor network. Wired network for detecting parameters is possibly connected systems. Wireless monitoring system gives easier wiring
more dependable. But, a WSN (Wireless Sensor Network) can give dy- setup feature than wired system [27]. Fig. 7 shows benchmarking of
namic versatility and cost free shifting. WSN gives opportunity to utilize acquired data from wired and wireless [27].
remote signal communication to PV-DG systems. A XBee PRO OEM Device performance is an important aspect for normal buyers while
module was used by Andreoni. It has data transmission speed of purchasing monitoring system. On the contrary, ZigBee technology is
250 kbps. Microcontroller unit was used as Data-Driven Decision- vulnerable from security aspect. It can be breached by mid-ranger
Making (DDDM) part with control managing purpose. This system used hackers. Also, ZigBee has range limitation for RF features. Obstacle can
USB to connect PC (Personal Computer) and MCU (Microcontroller create communication disruption to RF transmission. Address alloca-
Unit). A RF transceiver, connected with PC, was designed as the main tion rule for ZigBee is much more consistent. If any device does not
supervisor for remote system. acquire a network allocated address, it will be detached from a network
Fig. 3 shows the remote monitoring system proposed by Andreoni system and turn into a parent-less node. Issues of ZigBee are as sum-
that is comprised of two main parts [7]. The first part is observing and marized,
control portion for getting information and second part is for trans-
mitting information. A PV system of shunt-connected modules linked to • Signal interference from other senders, nearly at the same frequency
a commercial inverter, from SMA Solar Technology – model Sunny Boy • Limitations on the bandwidth of the medium/channel
1200. The information obtained from inverter were output voltage, • Low Coverage and loss of signal in basements, lifts and sites with
current, apparent and reactive power supplied from inverter to the grid. multiple floors
Similarly, the information from PV system (DC current-voltage and • Discrete communication
power output) and environmental parameters (irradiance, average
temperature of module back surface, wind speed and surrounding 2.3. National Instruments (NI)
temperature) were monitored as well.
The remote communication uses full duplex system utilizing ZigBee Data Acquisition Systems (DAQ) has the function to measure and
protocols, following IEEE standard. It features 250 Kbps transmission store information gathered from many channels at the same time. The
speed for maximum 125 m [23]. Monitoring control system was de- system has about 8–32 peripheral channels. A perfect data monitoring
veloped on DSP using DSPIC 30F3013 microchip and ZigBee Co- system utilizes a particular ADC (analog to digital converter) for every
ordinator. The remote system used in Andreoni's project worked as a channel. Information is acquired in parallel, and events in every
mesh network, with four radio devices of ZigBee [7]. First one is ZigBee channel can be computed continuously. NI focused on real-time mon-
Coordinator as a master unit, and it was connected with PC [7]. Other 3 itoring to check PV system performance. In reacting to the business
parts were arranged as End Devices (slaves). A basic HMI software sector request, NI has built monitoring device for PV modules/cells
interface is shown in Fig. 4. which is financially considerable and can to help perform tests on
An integrated circuit for electrical power measurement, ADE77531 modules with more accuracy [29].
model, performs signal processing for AC variables of inverter [7]. A SCXI System: PV systems can be embedded into the distribution grid
dsPIC 30F3013 processor does the signal processing and data acquisi- if there is no contortion of the parameters deciding the energy quality
tion of PV panel and weather parameters. Furthermore, control ad- from the new system [8]. Following this reason, Aristizabal came up
ministration allows different activities of panel, i.e., MPPT activity with a NI-SCXI based equipment that allowed evaluating the technical
conditions, grid detachment if needed, smart failure recognition system, efficiency and standard of power produced by a prototype of photo-
etc. A software was developed using C programming language. voltaic plant [8]. The hardware was able to do constant information
In Rashidi's System, Fig. 5, the proposed monitoring system used
ZigBee device at PV board's intersection box and on chip USB connec-
tion to an observing PC (organizer) [24].
In Fig. 6, a block diagram of the end device is shown. CC2530EM
component was used for this work [25]. A DC-DC converter was used to
give necessary power output for system (3.3 V).
Yujie proposed a custom-built design with WSN. The remote sensor
systems had different sensors hub structure [26]. Every hub in this
system had four channels for analog sensors. Collected information was
sent to the main module by ZigBee and then transferred to a remote
location using GPRS and the web. The GPRS model of using dial-up is
focused on PPP link (Ethernet based point to point convention) [27].
Sensor system administration of this work is divided into three sections:
information gathering and RFD transmission, information sending of
primary nodes and system control of ARM+TinyOS. There is a possi-
bility of data loss for any obstacle issue in this system.
Rashidi introduced a custom-built hardware using ZigBee
Microcontroller CC2530 in his work [24]. For monitoring each module,
the expense of additional circuits is higher. Data logger, sensors and
microelectronics have made it possible to create economic arrange-
ments to pursue such requirement. A remote sensor inside a module
cannot just indicate the accurate position of the module inside a PV
array, but it can also decide its seriousness by reporting the system loss.
This methodology would obviously prompt a noteworthy decrease of
Fig. 3. Proposed system flowchart using WSN [7].
system collapse, also decreases extra-work. ZigBee can maintain various

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Fig. 4. Basic HMI software interface with PV system and meteorological information.

computing to provide PV system performance data, and additionally

energy quality. Furthermore, the hardware could similarly be utilized
for measuring environmental parameters. The hardware was tested for
PV system that is connected with BIPVS (Building Integrated Photo-
voltaic Systems) concept based local grid. Fig. 8 represents the photo-
voltaic station architecture, including equipment utilized to monitor
performance and variables for measuring power quality. The system
had three units: SCXI 1000 for data acquisition and adjusting the signals
with 8 input channels, SCXI 1125 module and a SCXI 1313 terminal
block for conditioning down the voltage signals in acceptable range
(−10 V – +10 V).
VI processed current and voltage data from sensors. The utilization
of these information for generation output follows the standard IEEE
929–2000 to calculate the quality power produced by solar modules.
Fig. 9 demonstrates the front interface of VI (Virtual Instrument device)
to classify PV system power quality. The figure shows (left side) output
of each required parameters, characterized by IEEE 929–2000 standard.
The outputs of sensors appear in bar-chart showed in the right side.
These measurements show if PV system satisfies required power quality Fig. 6. End device flowchart diagram [24].
standards.

Fig. 5. Block diagram of Rashidi's monitoring system [24].

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unit comprises of sensors, a data acquisition card for checking and

managing system and breakers for different circuits. The developed
software for this monitoring system could check every aspect of the PV
system (Grid, inverter, load and PV array) and other parameters like
current, voltage, apparent-active-reactive power, frequency, different
phase data, etc.
NI-CompactRIO & NI-WSN Module Based System: In Moreno-
Garcia's work, the NI-CompactRIO based device could detect environ-
mental parameters, power production of the PV plant, and power
quality for grid connection [31–33]. Real time PV system monitoring
variables were measured using NI-CompactRIO by Trillo-Montero [34].
A programmable controller was introduced for monitoring inverters,
Fig. 7. Data graph of acquisition and monitoring [27].
that was suitable for receiving 8 channels parameters for DC and AC.
The monitoring device allowed observing monitored data and also the
possible estimation of power quality. PQ (power-quality) estimations
were prepared using cRIO module with a time delay of 200 ms for every
recorded log. For remote monitoring, the device and programming
sorted out recorded data and sent to MySQL database.
For data transmission, a Wireless Sensor Network (WSN) was uti-
lized. A PC server gathers, assesses and shows recorded information of
the plant [35]. NI-WSN9795 chip works as the network coordinator in
the system. Another module, NI-WNS3226, was connected to four
sensors. Among four connections, first two are ± 10 V inputs; re-
maining two are for measuring temperature data. The cRIO controller
had been used before in different systems [36]. CRIO9075 based con-
Fig. 8. Aristizabal system’s block diagram [8]. trollers were connected to 3 inverters. Controllers of cRIOs keep run-
ning following IEEE standard 1588, that functions like PTP to stable the
VI acquires the input and output voltage-current data of inverter output [37]. IEC 61000-4-30 standards were followed for measure-
and analyzes them to calculate inverter conversion efficiency. It also ments of energy and power [38]. An installed cRIO9024 chip permits
shows the PV system conversion efficiency using power generation further activities regarding power quality issues and unwanted signal
output and solar irradiation inclined. In Fig. 10, data demonstrates VI filtering. A GPS device was used to keep time reference for every remote
panel to determine the proficiency of inverter along with PV system. device [39]. This monitoring system was designed depending on the
The figure shows a reading of parameters like voltage, power output, NIcRIO data monitoring and LabVIEW®. If any fault occurred regarding
current, inverter proficiency from a test by Aristizabal [100]. communication error, the developed program would stop data acqui-
NI USB-6221 DAQ: Bayrak and Cebeci introduced a system using NI sition and sharing.
USB-6221 DAQ [30]. PV system parameters (voltage and current) were
acquired from system and data were observed continuously using data
2.4. BeagleBone Black controller
acquisition card and LabVIEW. Grid connected parameters such as ac-
tive-reactive power, phase angles were also checked along with power
Ngo and Floriza worked with a BeagleBone Black device for their
stream between main grid, load and PV system. Solar irradiation and
work in 2015 [40]. A monitoring system that observes owner's use and
module temperature data were acquired from PV panel and inverter
measures generated energy of grid-tied PV system was developed. A
parameters. Collected parameters data were sent to webbox using
web and a mobile application were developed to present the data. The
RS485 communication [30]. Webbox modem unit is utilized as in-
web application employs an algorithm that could project the house-
formation storage. It also enables remote monitoring. The monitoring
hold's monthly bill based on power consumption and power generation.

Fig. 9. PV System power quality demonstration of

Virtual Instrument SunVIEW [100].

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Fig. 10. PV System and inverter efficiency mea-

surement by VI [100].

This provides information so that the user can consciously make ne- microcontroller unit (MCU) and a DC/DC unit. Fig. 13 demonstrates the
cessary steps to reduce their monthly energy consumption, thereby utilized PLC module architecture. DC/DC part changes over different
reducing the electrical bill. The projected bill was based on the gen- voltages of PV system. Yield voltage of a PV module ranges from 30 to
eration rates of MERALCO (The Manila Electric Company, also known 60 V. So, DC/DC unit was used to increase system's limitation for de-
as Meralco, is the Philippines' largest distributor of electrical power). tecting output. Voltage divider has been used for detecting voltage;
The energy monitoring system was developed to read and send the shunt resistor worked like converter for current, and sensor was used to
following parameters: (1) voltage, (2) current, (3) output power, and measure temperature of system.
(4) the total energy used by the household from both the solar and the Communication signal through powerline is driven by analog circuit
utility grid. The obtained values were transmitted to both the server coupling. Power amplifier amplifies the generated amplitude shift
and the android device via SMS. However, one of the limitations of SMS keying signal, and then sends to power line. At the other end, in re-
transmission is the bulk sending of texts. The BeagleBone Black pro- ceiving device, noise gets cleared by a band pass-filter and weak signals
cesses recorded data. are amplified again by amplifier. Capacitors placed in between the
The hardware design consists of the following: (1) INA219 sensor transformer and the electrical power line to secure high voltage pow-
for DC power measurement, (2) Cirrus Logic CS5463 for the AC power erline from DC. Master PLC unit forwards collected information from
measurement, (3) Beaglebone Black for the main controller, and (4) entire system towards data-logger for preservation. A CRC (Cyclic
GSM module to send sensor data to the server and mobile application Redundancy Check) module is used to recognize changes of the ac-
[40]. The schematic layout of the system deployed in the household is quired information. If a CRC fault occurs, both slave and master PLC
shown in the following Fig. 11. modules dispose acquired information for maintaining perfection. A
The INA219 DC sensor connected to an Arduino and the grid-tied shunt resistor has been utilized for altering over current into measur-
inverter. The current and voltage output goes to Arduino which is able voltage unit. Amplifier is used to boost altered voltage. Voltage
connected to the BeagleBone Black via USB to serial interface. The divider makes it possible for analyzing up to 60 V for this system.
Cirrus Logic CS5463 IC is intended to compute active power, reactive Roman worked with a smart module with PLC communication and
power for single-phase, apparent power, IRMS, instantaneous power, MPPT capability [41]. The PLC module was frequency shift key (FSK)
VRMS and 2–3-wire power metering applications. A python script to communication based along with baud rate of 2400 bps and 132 kHz
control the BeagleBone's GPIO and UART was used to communicate carrier frequency.
with the various sensors and GSM module connected to the board.

2.5. Power Line Communication (PLC)

A PLC (Power Line Communication) based monitoring system for

PV was proposed by Jinsoo in 2015 [1]. PLC modules were connected
for monitoring every PV module. Data logger combined information of
each module along with inverter. Plc innovations have been utilized for
better metering of grid and home system in local locations. The mon-
itoring system was planted at a PV system of 16 PV modules of 400 W
[1]. The system is consists of four components: two master and other
two slave modules of PLC along with data logger. System's basic ar-
chitecture is shown in Fig. 12. Slave modules were placed at back of PV
panel. These modules measure current, temperature and voltage. The
master component is placed near inverter. This component processes all
the information gathered from the slave modules.
Data logger is attached to master PLC module using a serial com- Fig. 11. System schematic layout. The blue lines represent monitoring system connec-
munication line. WiFi and Ethernet communication feature of the data tions and the flow of measured data. Dotted lines represent wireless data transmission
logger allows client to connect with the monitoring system remotely. [40]. (For interpretation of the references to color in this figure legend, the reader is
referred to the web version of this article)
The system has four sections: analog coupling circuit, detecting unit,

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Fig. 12. Data logger, smart device and PLC based architecture of
solar monitoring system [1].

aspects. PLC mostly depends on the electrical wiring of the building/

place. The wiring is also susceptible to electrical interference. There are
known issues with high load devices interfering with Powerline adap-
ters, list includes refrigerators, microwaves and vacuums. If it is
plugged into a surge strip, the data stream will be interrupted, and the
device will not work. And also, the connection is rather slow with data
transfer speed of 50 Kbps to 350 Kbps. Expense turns out to be high
since PLC modem chips are costly. Expensive module of PLC for all PV
modules is not desirable, nor plausible for home based system.

Fig. 13. Low budget proposed PLC module [1]. 2.6. Peripheral Interface Controller (PIC)

A string box as a master unit and another module box as slave unit PIC18 Microcontroller: Naeem presented the engineering of a basic
was developed by Jonke [42]. Microcontroller (MCU) attached with web-system for remote monitoring of PV-device using PIC micro-
power line transceiver were used for both parts. Power line transceiver controller [9]. The system allows different parameters reading of a PV
had feature of 9.6 kbps to 115.2 kbps; and it utilized multi-phase establishment, for example, temperature and voltage to be precisely
modulation scheme in 175–13 MHz range. logged, then transferred to local PC via LAN. In the present day, ex-
Another communication module and smart monitoring system, de- tensively used protocol for communication is Ethernet. It has some
veloped by Sanchez-Pacheco, was installed in CENELEC EN 50056 [43]. essential benefits like better quality of data transmission and free from
The module featured max 16kbps baud rate using modem for FSK. electromagnetic impact. The monitoring device is featured with
Napoli demonstrated DC bus based PLC, attached to modules of PV Ethernet. LAN along with implemented server uses TCP/IP. EEPROM
in series connection [44]. The microcontroller was associated with FSK has been used for service like web demonstration of the logs. Basic
modem (half-duplex) by SPI, that was used to transfers information. functioning of the connected web server of the system proposed by
Herndon built a FSK modem based brilliant combiner to use on Naeem is demonstrated in Fig. 14 [9].
power line of direct current [45]. The modem featured improved CRC, The system utilizes PIC18F2620 MCU along with Ethernet chip
channels and amplifiers; it also had a CSMA (carrier sense multiple ENC28J60 [49]. To reproduce a control voltage, a potentiometer based
access) plan. No graphical UI was given. variable DC voltage was utilized.
Han came up with HomePlug Green PHY (HPGP) PLC based PV PIC16 Microcontroller: Husain and Zainal proposed a monitoring
monitoring system [46]. OFDM (Orthogonal Frequency Division Mul- system using PIC16 microcontroller on Client/Server architecture re-
tiplexing) was utilized here. OFDM has particular attribute of band quirement [50]. As indicated by the design, one or more devices could
efficiency along with immunity to high noise [47]. A renewable energy be connected the monitoring system, which works as a local server as
gateway (REG) recorded data from every PV module. Clients cloud well. The system would send alert to the connected computer if a fault
access to REG via remote or wired system to check PV architecture occurs. PIC16 microcontroller based system structure of PV monitoring
condition. system is demonstrated in the following Fig. 15.
Rosenthal, A. L showed an AC Power Monitor [48]. He used AD7750
IC for this device. The IC was intended for the purpose of energy
measuring task, e.g., two input channels of differential analog data
(current, voltage). It has high and low-pass filters, amplifier and four
quadrants full operation. Error rate of used chip is about 0.3%. The
device could store data for 5 months. Constant monitoring is accessible
using a computer. Using powerline communication, encoded trans-
mission is modified on home based unit wiring of power. Different re-
ceivers installed in the house can get this data if they are connected to
electrical lines. Transceivers in standard of ×10 convention have been
utilized for this system [48]. Experiment output demonstrated that a
precision is kept up for 0.5 leading to 0.5 lagging power factor [48].
Despite the positive sides of PLC use, there are some mentionable Fig. 14. Proposed systems functionality flowchart block diagram [9].

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M.M. Rahman et al. Renewable and Sustainable Energy Reviews xxx (xxxx) xxx–xxx

Fig. 15. Flowchart diagram of the proposed system [50].

Solar Energy Generating Systems (SEGS) should be planned prop- have the ability to enhance the accuracy of time [53,54]. The main
erly before installing the system for ideal operation. In planning SEGS, concern of LwIP TCP/IP application is to lower asset utilization and
two channels are supposed to receive input from each array of PV. The having a complete TCP. LwIP is used as working OS and runs auto-
main channel to be connected to a controller for charge that works as matically. This is why LwIP becomes reasonable implanted monitoring
battery charger and provides electrical power to household machines system with space for about 40 kb ROM [55]. The usage of LwIP con-
during the night time when there is no sun. The 2nd channel is con- vention of TCP is shown in Fig. 18.
nected with monitoring device. The PV array sends the information to Fundamental TCP protocol is divided into 6 function stages. For
microcontroller via USB ICSP PIC Program, and the PC gets the in- input processing tcp_input(), tcp_process(), tcp_receive() are used and
formation via serial port ( Fig. 16). for output processing tcp_write(), tcp_enqueue(), and tcp_output()
The PV generation output is changed into digital signal and sent to functions. Utilization of OS requires more storage. When task switching
microcontroller unit PIC16F877. Information is processed by developed occurs rapidly, it reduces system-ability. So, the utilization of non-OS
software for storing into a hard disk drive. Apache HTTP Server 2.2.15 ends up being a more sensible decision. Programming language C was
software was used to recover data from internet. The system was as- used for data transferring from inverter-controller, also for transferring
sociated with webserver via TCP for real-time monitoring [51]. to the web server. LabVIEW was utilized for digital signal processing,
For PIC based system, program size will be large since RISC signal generating, spectrum analysis, etc. [56,57].
(Reduced Instruction Set Computer) is being used. PIC design restric- Most of the microcontrollers, particularly PLCs (Programmable
tions are as follows, Logic Controllers), are conventionally coded to use in custom-built
systems. A PLC program cannot be edited once programmed because it
• PIC has just a single accumulator. is managed by a ROM (Read-Only Memory). On the other hand, a RAM
• Insufficient guideline manuals. (Random Access Memory) is designed to dynamically update its
• Register banking switch is needed to access RAM of different memory, which is why it is improper to perform repetitive assignments
equipment. on RAM that microcontrollers are designed to execute.
• Functions and records are not equilateral.
• Inaccessible program memory. 2.8. Reference cell based system

2.7. ARM Cotex-M3 processor & LwIP stack Guidelines for monitoring performance of PV systems demand PV
electrical and climate data measurement [10]. Most PV monitoring
Conventional expensive monitoring devices follow IPC standards for systems are used for grid-connected PV based plants and they focus on
PV monitoring [12–14], moreover, it is fairly difficult for maintenance
and repair the entire setup as an aftereffect of fault occurrence and
communication disruption. Chengmei suggested LM3S9B92 (ARM
Cotex-M3 processor) for controller device to monitor data using LwIP
for grid-connected PV system [52]. The system could perform data
logging, processing and fault recognition of the PV system. The mon-
itoring device was developed using LwIP & Cortex-M3, and its features
were: (1) utilization of regular Ethernet for high-speed data transfer; (2)
controller modules were placed for optimization, (3) easy to use user
interface. Architecture of the monitoring system is demonstrated by
Fig. 17. Device comprises of system inverter, remote PC and connection
of other components. After gathering information from various sensor
inside inverters, the controller transfers the data to the module of
network controller. Then the data is prepared and uploaded.
Micro-controller unit as network controller needs greater integra-
tion, less power utilization along with powerful processing proficiency
since it is the primary unit of the monitoring system. ARM Cortex-M3 is
a coordinated chip and consolidates 32-bit ARM® Cortex™-M3 v7M
Harvard engineering. It gives platform to detect the issues of insignif-
icant memory execution and decreases pin check. Also, the processor
comprises of a completely inbuilt MAC protocol along with physical
interface of network. The system follows IEEE convention of 1588, that
Fig. 16. Data acquisition system flowchart [50].
accomplishes precise harmonization for clock used in system, and also

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M.M. Rahman et al. Renewable and Sustainable Energy Reviews xxx (xxxx) xxx–xxx

Belhadj-Yahya's work, reference cells should be placed throughout the

module to capture most of the deviations caused by solar irradiation
incident angle, shading and module temperature. Ideally, a unique
monitoring module could be placed with reference cells set in the
middle. Voltage is perceptive to temperature and current is ex-
ceptionally sensitive to irradiation. So, change of irradiation can be
sensed by monitoring reference cell current. Additionally, by matching
current from the left and right reference cells shading can be detected as
well. For PV systems with MPPT, current-microcontroller can be used to
record data from reference cells and the data can be utilized to re-
cognize system error issues. Comparison of output will be different if
module current drops from reference value. This will indicate shading
issue and load should be detached from shield module to avoid any
damage

2.9. Module Interconnection Circuit (MIC) & Acquisition-Control Unit

(ACU)

Fig. 17. Grid-connected PV system monitoring architecture [52]. Ulasenka proposed a monitoring system that allows the fault de-
tection in each module of a PV plant [11]. For that, circuits are attached
MPPT control [58–66]. Urbano's monitoring device was based on 5 W in parallel to each PV module for sensing voltages. A custom device
as reference to managing control of MPPT for an 2.6 kW plant [66]. In permits fault detection for every module obtaining the real output
his work, halfway shading was prioritized by the utilization of reference power with MPPT feature. The system was planned without irradiance
cell. Reference cells were also used to monitor PV modules cell con- or temperature sensors. Usually, the power output from the inverter is
nection for fault detection in problem areas [67]. For both cases, re- correlated with the estimated power. In some cases, PV system para-
ference cells utilization was limited to yield assessment or recognition meters and environmental data can be obtained by other means in a
of shading [66,67]. statistical manner [62,69]. It is possible to measure current of each
Besides performance checking, monitoring system is also important module using shunts in DC part but it always requires disconnection of
for identification of system faults and system optimization. The per- that module from the rest of the system [70,71]. The approach is based
formance monitoring techniques can be characterized into three cate- on the combination of several electronic circuits connected in parallel
gories. The primary technique follows the IEC rules and is used by most with the components of the PV system. In this way, the system could
of the studies concentrating on starting system evaluation [10,58–60]. check performance of PV systems without modifying their circuitry. The
Different electrical parameter sensors and environmental sensors hardware system consists of two different circuits, the Module Inter-
should be installed along with information processing architecture for connection Circuit (MIC) and the Acquisition and Control Unit (ACU)
every sub-system. The technique requires expensive equipment and [11]. MIC is connected to each module and one ACU to control a
must be utilized for large PV structures. Another technique maintains complete array. MIC is connected to a module by only two wires, to the
PVSAT-2 European standard [62,63]. This utilizes space satellite to same points used for their series interconnection, in parallel with those
transfer data along with PV system loss information and to observe as it is shown in Fig. 19. This figure includes several ACUs controlling
system performance from a distant location. This technique is con- each module string with the only limitation of the electrical losses on
strained to the specific European ventures and is costlier to use in dif- the wires.
ferent areas. The third technique utilizes performance monitoring for Following load of the system, current varies and also module-vol-
PV output power [64–66]. Monitoring is performed at DC-DC converter tage changes. It influences the working procedure of all the strings. To
level over a MPPT subsystem. Principle goal of MPPT is to operate correct this effect, the total voltage of the string is measured at both
system at defined level for changing loads, irradiation and temperature ends of the string. In this model, the voltage is an explicit function of
[64]. This technique is used for both performance monitoring and fault the module-current. Module to module strategy allows the character-
identification [65–67]. The strategy of MPPT technique requires ad- ization of the individual modules and enables to detect individual faults
justment for covering fault location along with array current detection. [11].
For smaller PV structures with and without MPPT, a performance
monitoring strategy was developed by Belhadj-Yahya [68]. 2.10. Monitoring using DAS/DAQ
Utilizing smaller reference cells for forecasting output of array
power has no less than three favorable circumstances. Initially, mea- Most of the Data Acquisition System (DAQ/DAS) for PV monitoring is
surement of current-voltage is limited to their values. Next, a small load based on two different devices. Electrical parameters like DC power, cur-
is not required for measuring current of array/module. Finally, less rent, voltage, PCU condition, reactive-real power of the system are observed
difficult circuit design for acquiring and processing information. In by the inverter room DAS. And the rooftop/exterior DAS monitors weather

Fig. 18. LwIP stack TCP computation [52].

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M.M. Rahman et al. Renewable and Sustainable Energy Reviews xxx (xxxx) xxx–xxx

Fig. 19. M3S monitoring system along with PV array

circuit [11].

parameters like solar irradiation, ambient temperature, wind speed [72]. 2.12. Comparison of different monitoring systems
System architecture of from Begovic's work is in the following Fig. 20.
In work of Begovic, M., measured solar insolation data using DAS/ Evolution and performance analysis charts over time from different
DAQ and calculated data using software had a noticeable deviation reports and articles are presented below (Table 1 and 2). The charts
back in 1996 [72]. There was a mismatch of calculated and monitored concentrate on the features of remote monitoring system, used tech-
data because efficiency was calculated utilizing input and output power nologies and data storage related works. The tables show year, re-
measured from system. This was wrong system proficiency on account search-venture data, Acquisition and Communication Layer section
of rooftop curvature [72]. indicates the devices and innovation utilized for information transfer.
In the Supervision Layer, different types of data storing technologies
2.11. Monitoring via satellite have been used.
The earlier step started in 1994 and completed in 2001. In this
Krauter described a monitoring system that used satellite ARGOS to segment, in the majority of the works used inverter as the main device
transmit data to web. The ARGOS satellite transmits rate is 10 bytes/ for data monitoring of photovoltaic systems.
15 min [73]. The satellite has a permeability circle of around 5000 km Following steps of an innovative jump from 2002 to 2006, which
width. Communication speed is somewhere around 32 bytes transfer- exhibits the Acquisition and Communication Layer utilizing particular
rate at 8–12 min. Signals from analog sensors are converted to digital in sensors, photovoltaic system parameters and data logger devices.
about 15 min and after that passed to the send-buffer. Transmitter From period 2007–2015, where the utilization of sensor systems for
transfers data from buffer which takes 30–40 s for each buffer packet. measuring the standard parameters of the PV establishment are seen.
The system allows 12–14 satellites communication for each day with 32 The utilization of new technologies for communication between system
bytes transmission rate for every contact. The satellite based monitoring and data logger are done by wire or wireless technologies like GSM,
device was intended to encourage checking of various types of renew- ZigBee, etc. As data logger, the utilization of National Instrument
able energy systems parameters [5]. Every information through analog Technology, Arduino, Waspmote are seen. Monitoring platforms still
input has to pass an input multiplexer and then the signal is enhanced comprise of a computer for most PV systems using LabVIEW pro-
by differential amplifier. After that, a filter for low pass eliminates gramming that permits to have remote access.
noises. The system could work for maximum output of 12 V.

Fig. 20. Flow chart diagram of the data acquisition

system at The Aquatic Center [72].

11
 Table 1
Comparison chart of different Monitoring Systems over time (1994–2006).

Research/Project IOT Device Contact Equipment Log Interval Controlling Platform Data Preservation
Acquisition and Communication Supervision
M.M. Rahman et al.

3.3 MWp PV Plant Control System (1994) [74] Peripheral control system of Inversor; Ethernet Fiber optic lan Protocol 1200 data/s Workstation of Microvax Tape disk and Floppy disks
seira tcp-ip
Sunpac: The Remote Monitoring of Photovoltaic Installations Sunpac Control cabinet Cable – Permanent surveillance center Send log using modem, save to floppy
(1995) [75] computer diskette or computer
Monitoring System at Center for renewable energy and eco-energy Pyranometer, energy meters, voltage Cable 10 s Computer Computer and CD
house (2001) [76] dividers, thermocouples
Monitoring and dissemination on the web of PV plant at Inversor monofasico tauro prm 5000/8 Fiber optic Cable 300 s Computer MySql data Base.
Universidad Pontificia Comillas (2002) [77]
Satellite monitoring system for remote PV systems (2002) [78] PTT (platform transmitter) Satellite Argos 10 bytes/ Argos Satellite –
15 min
Real-time, web based monitoring system (2004) [79] 14 different sensors Cable 60 s Computers with NI device Temporary files on computer
PV- hybrid system's remote monitoring and control (2005) [80] Analog input modules of Adam 4017, GSM using series communication – Windows ce 5.0 xscale based MySql data Base.
4051 & 4056 port computer
Hybrid wind-PV- battery renewable energy system's real time Digital Power Meters Cable – Ethernet Plc omron connected Excel formatted.csv file
monitoring and control based on web (2006) [81] computer

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Table 2
Comparison chart of different Monitoring Systems over time (2007–2014).

Research/Project IOT Device Contact Equipment Log Interval Controlling Platform Data Preservation

GSM-based monitoring and control (2007) [82] Different Voltage Dividers, PV sensor cell and various current GSM 2.8 ms Monitoring and control system (MCS) –
shunts
Remote data monitoring for a solar and wind-based power system Ni-4060 digital multimeter Cable – LabView installed computer –
(2008) [83]
Wired and wireless remote control of photovoltaic system (2010) Various sensors for system voltage, actuators current, Both Wireless & Wired – Computer –
[84] pyranometer
Simbalink: towards a sustainable and feasible solar rural Voltage divider circuit GSM 1120 bits 3 G modem connected to computer with Centric database
electrification system (2011) [85] USB connection
SM 2: solar monitoring system in Malawi (2011) [86] 1117_0 - Voltage Sensor & i-Snail-VC-100 AC Current Sensor Cable 6 sms/day Lamp Linux & Apache installed computer MySql
100Amp from Phidget Inc.
ZigBee Wireless system for monitoring of PV panels (2011) [24] Cc2530 from Texas Instruments Inc., Step-down dc-dc ZigBee WSN – Computer –
converter, sensors for current-voltage
Photovoltaic Remote Monitoring System based on GSM (2013) Different sensors for temperature, voltage & current Cable 300 s Computer .csv formatted file
[87]
Wireless sensor network for panel level monitoring (2014) [88] Wireless Sensor Network XBee – Central computer –
Renewable and Sustainable Energy Reviews xxx (xxxx) xxx–xxx
M.M. Rahman et al. Renewable and Sustainable Energy Reviews xxx (xxxx) xxx–xxx

3. Impact assessment Alternatively, the outputs of a monitoring system can be used to report
the direct benefits to higher management and may be crucial in the
3.1. Economic assessment adoption of solar power on a larger scale within a company.
Andreoni proposed ZigBee tech-based monitoring and control
It is true that a solar PV system will produce the same amount of system for PV-DG [7]. ZigBee modules price varies from US$3-US$20/
energy with or without monitoring, yet there are very strong reasons to each following different models [92]. A standard ZigBee communica-
include a monitoring system in the project which is as follows, tion kit (including router) with different features may cost up to US
$300 [93]. The outcomes of system tests allows demonstrating an idea
1) Detecting problems before they have a chance to become major of a low-budget remote monitoring system option for performance
issues. checking, error recognition and control of PV systems. On the other
hand, A NI SCXI product may cost from US$500 to US$2000 following
A monitoring system allows detection of system performance issues the model [94]. The product allows the advancement of Virtual In-
that might be very difficult to detect otherwise. For example, imagine struments (VI's) with a practically boundless customization options
there is a nearby building demolition and the surface of many PV [95]. Jinsoo's system reduces the expense of monitoring system elim-
modules suddenly becomes dirty. With a monitoring system, the effect inating the need for costly modem for communication of PLC module
will be noticed within one day. Energy production will show a drastic [1]. A PLC microcontroller may cost from US$250 to US$700 [96].
decrease in performance from one day to another, the issue can be in- Previously used DAQ/DAS based monitoring systems had an issue of
vestigated and the affected modules can be cleaned. equipment unavailability due to less production of electronic items.
According to calculation, a US$30 investment (for cleaning PV Therefore, back in those days, it was literally expensive compared to
panel) in a 4 kW system could see returns of US$1200 [89]. For a 1- these days. Regarding Satellite based system, primary expenses for
megawatt system, in term for system failure, the additional cost of transmitter is almost US$1200. And another unit that is used for pre-
string monitoring equipment ranges from US$10,000 to US$15,000, processing is about US$600 [5].
which is the equivalent of US$500 to US$750 annually over a twenty-
year time span [90]. Without a monitoring system, an entire month can
go by without the system owner noticing the problem. Then, there will 3.2. Environmental impact
be an unwelcome surprise when the electric bill is suddenly higher due
to the sudden decrease in PV system production. This is a possible The electrical output of Solar-PV modules is dependent on two key
scenario in which a monitoring system actually provides an economic factors or variables: 1) Incident Sunlight and 2) Module Temperature.
benefit. If PV module is monitored separately, it becomes much simpler All other environmental & weather factors (cloud, soiling, rain, snow,
to pinpoint the location of performance issues. hail, wind, etc.) can be considered as second-order factors. While
output current of Solar-PV modules has a positive correlation with
2) Becoming eligible for specific state/federal/utility incentives. sunlight, output voltage has a negative correlation with module tem-
perature. It is surely understood that the environmental impacts affect
Some incentive programs are based on system performance, and PV system performance in long term. Three key weather variables were
they actually require the PV system owner to use monitoring. An ex- distinguished: ultra violet light intensity, ambient temperature and air
ample of this is Renewable Energy Credits (REC), which can be cashed humidity.
in and it is based on the total amount of clean energy produced. PV modules solder bonds get weaken because of high temperature
Changes of REC rate over the time for a particular country is shown in [97]. PV modules debasement element depends not just on the prop-
Fig. 21. erties of the material, additionally by the change of parameters of the
It is important to note that renewable energy credits can be different climate. It is observed on revenues from power outcomes. Use of
to certain countries or states. monitoring system to check system performance keep the investors
aware of the output from PV panels, thereby when modules reach a
3) Proof of PV system effectiveness. negative margin from profit line, investors pursue the option to imply
new panel. Thus, in different ways, environmental impacts of using
Electric utility bills by themselves may not be able to capture and other means of power generations get reduced. Additionally, the
reflect the entire range of benefits achieved with a PV system. monitoring unit does not impose any negative impact on environment
either. Along these lines, the generation of power from a particular PV

Fig. 21. National Voluntary REC prices and western wind REC
price (in U.S.), January 2009 to August 2016 [91].

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M.M. Rahman et al. Renewable and Sustainable Energy Reviews xxx (xxxx) xxx–xxx

board can be forecasted, and also a more exact analysis of income and Analog input pins. According to market analysis, a complete monitoring
cost of electrical power could be prepared [98]. The general output of system for PV using Arduino with basic sensors like temperature, hu-
PV cell shifts on different irradiance and temperature for adjustment in midity, solar irradiance, voltage-current sensor etc. and other features
day time, thus power output from PV module also changes [99]. like local and cloud data storage, SMS/Voice call notification, power
saving by turning of monitoring device at night-hour, solar tracking etc.
4. Proposed monitoring system should not cost more than 500 to 700USD. This expense is much lower
compared to other monitoring technologies discussed earlier. Fig. 22
Use of microcontroller Arduino as the main unit to process and flowchart diagram is a prototype to show a basic system architecture
preserve Environmental and Photovoltaic System's log files on local that can be applied to give the monitoring system a versatile feature.
storage and enabling access to the logs from remote area can be used to Smart monitoring, fault detection, automatic solar tracking, control of
minimize cost of web hosting expense. It is an alternative method for PV system, etc. feature can be achieved reducing maintenance cost, less
monitoring PV system from the discussed technologies earlier and it circuit complexity, and also user customization ability since Arduino is
meets almost all the required criteria of PV monitoring. It is also fa- an open-source system. Use of Arduino micro controller for PV system
vorable regarding demerits of other monitoring technologies. Arduino will give many more development scopes for smart monitoring system.
Ethernet module based storage device connected to main Arduino unit To summarize the reasons behind proposing Arduino based monitoring
(UNO/MEGA etc.) can preserve PV system's data in CSV/htm/txt etc. systems are,
format. And this can be accessed from remote locations through in-
ternet if interfaced appropriately. Thus, the need of web server can be • Inexpensive compared to other monitoring devices and easy to find
reduced. Web server demands a regular cost to keep up with time, that on the market.
can be enlisted as a maintenance cost. Also, to enable internet access to • Different Arduino compatible modules/shields and sensors are
Arduino, GSM module can be used in case the Ethernet is not capable of available to perform specific tasks.
getting Arduino connected to the internet. Also, stored data can be • Can be patched for both wired and wireless network.
accessed using WiFi shield connected to Arduino. Therefore, even if • Easy to understand coding (and circuit) instructions and supports
there is no internet connection, either through GSM or Ethernet, data are available online.
can be checked locally through WiFi or Bluetooth connection. Instant/ • Program memory can be accessed to modify the code.
last recorded data can be shown using local display. Both local and • Can be used for sensor reading, data processing and also publishing
remote access to the preserved data can be maintained without use of in an easy manner.
any wire/cable connection or any extra charge. If storage gets full after • Support both cloud and local server/storage facilities.
a certain time, which would be predictable depending on the connected • Easy to work with for both researchers and PV system owners, etc.
storage capacity and logfile size, it can be easily replaced with a new
one. There would be no major necessity to update Arduino coding or 5. Conclusion
connection settings. Various controlling feature for PV System can be
implemented as well. It can also be used for battery charging controller In most recent decades, the measurable performance ratio of PV
through solar panels. establishment has enhanced rapidly. Following different reasons, this
Since Arduino requires less operating power, the monitoring system change happened because of more exact module rating, better plan and
can be used as portable one using battery (9 V) or small solar module to establishment, and more dependable components alongside shorter
power up the microcontroller. To acquire extended feature, it is better times to repair faulty issues. Operational monitoring of the PV systems
to use Arduino Mega 2560. This model of micro controller provides 54 and analysis of recorded information has been the way to this nonstop
digital I/O pins, 15 of them can be used for PWM output, and also 16 change. General rules of PV plant monitoring have been accessible and

Fig. 22. Proposed monitoring system flowchart diagram for PV installation.

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M.M. Rahman et al. Renewable and Sustainable Energy Reviews xxx (xxxx) xxx–xxx

it demonstrated helpful result for a long time. These have been sup- [2] Chiandone M, Cleva S, Pavan AM, Sulligoi G, Monitoring applications of electrical
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