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Design of A 11 KW p Grid Connected Solar Photovoltaic Power Plant on 100 m

2 available Area in the Birbhum District of West Bengal

Article · July 2011

DOI: 10.3126/jie.v8i1-2.5100

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Souvik Ganguli Sunanda Sinha

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 Journal of the Institute of Engineering, Vol. 8, No. 1, pp. 105–112
TUTA/IOE/PCU © TUTA/IOE/PCU
All rights reserved. Printed in Nepal
Fax: 977-1-5525830

Design of A 11 KWp Grid Connected Solar Photovoltaic Power Plant on 100

m2 available Area in the Birbhum District of West Bengal

Souvik Ganguli1, Sunanda Sinha2

1
Department of Electrical & Instrumentation Engineering, Thapar University, Patiala
2
Department of Electrical Engineering, Calcutta Institute of Engineering & Management, Kolkata
Corresponding e-mail: souvik.ganguli@gmail.com

Abstract: The depletion of fossil fuel resources on a worldwide basis has necessitated an urgent search for
alternative energy sources to meet present day demands. Solar energy is a clean, inexhaustible and
environment-friendly potential renewable energy option. A stand-alone solar photovoltaic cannot provide a
continuous supply of energy due to seasonal and periodic variations. Therefore, in order to satisfy load demand,
grid connected energy systems are now being implemented that combine solar and conventional conversion
units. The objective of this work is to estimate the potential of grid quality solar photovoltaic power in the
Birbhum district of West Bengal and develop a system based on the potential energy estimated for an available
land area of 100 m2. Specific equipment specifications are utilized based on the availability of components in
India.

KEYWORDS: Diurnal variations; Daily Energy Output; Monthly Energy Output; Grid Connected
Photovoltaic (PV) System; PWM Inverters; Solar Radiation; Yearly Energy Output.

1. Introduction
Electricity is obtained from the PV array most efficiently during sunny daytime hours [1-4]. At
night or during cloudy periods, independent power systems use storage batteries to supply
electricity. With grid interactive systems the grid acts as the battery, supplying electricity when
the PV array cannot [5]. Energy storage devices (e.g. batteries) have been avoided in this work,
to reduce capital, operation, and maintenance costs. The grid connected PV system is well known
in various parts of world, and several technologies are available [6]. This research work focuses
on the development of a grid connected pv system. Additionally, there have been efforts to
develop the power electronics circuitry involved [7-9] and several types of inverters have been
designed [10-15]. Overall, the goal is to measure the potential of a grid connected PV system in
the Birbhum district of West Bengal using a solar-meter and to establish a demonstration of this
type of system using existing methodologies and available equipment.

2. Materials and Methods

To find the solar PV generation potential in the Birbhum district of West Bengal, solar radiation
over nine months (July 2008-April 2009, excluding October 2008) was measured using a solar-
meter. The diurnal variations, average monthly output and yearly output have been calculated and
the related graphs were plotted to show the seasonal variation [16]. The measured radiation data
sheet of Birbhum district for the month of April 2009 has been given as an example. Diurnal
variations for different months were plotted then monthly and yearly outputs were calculated.
106 Journal of the Institute of the Engineering

Observing the peak values, the monthly average peak was calculated, variation of the monthly
peak for a year was plotted and the average annual peak was calculated. For calculating output,
the efficiency of the PV module was taken as 14.3% [17]. Finally, a grid connected PV system
was designed with available technologies for an estimated plant capacity on 100 m2 of arbitrarily
selected land. The total plant capacity was estimated using the solar potential assement data
previously determined.

3. Results and Discussions

3.1 Estimation of Solar Potential & Possible Plant Capacity

Solar radiation was measured for the time period July 2008 to April 2009, with the help of solar-
meter.
Table 1: Calculation of Average Output April 2009 (Time: 10 AM)
Date PV Module Solar Output Monthly Average
Efficiency Radiation (Watt/m2) Output Output
(Watt/m2) (Watt/m2) (Watt/m2)
05.04.2009 14.3% 780 111.54
15.04.2009 14.3% 860 122.98
26.04.2009 14.3% 890 127.27
04.2009 14.3% 361.79 120.6
Table 2: Calculation for Diurnal Variations (April 2009)
Time Average Output Average Output Daily Energy Monthly Energy
(Watt/m2) (Watt/m2-hr) Output (Watt/m2-hr) Output (Watt/m2-hr)
10 AM 120.6 120.6
11 AM 138.9483 138.9483
12 NOON 129.653 129.653
1 PM 115.83 115.83
2 PM 96.0483 96.0483
3 PM 69.355 69.355
4 PM 46.713 46.713
04.2009 717.1476 21514.428
The results for the month of April 2009 have been shown as a sample (Table 1). Only the average
output calculation at 10 AM is shown in this table. Similar results were obtained at 11 AM, 12
NOON, 1 PM, 2 PM, 3 PM and 4 PM. The diurnal variation for the month of April 2009 is also
shown (Table 2).
 Design of A 11 KWp Grid Connected . . . 107

Figure 1: Diurnal Variations April 2009

Table 3: Total Energy Output
Average Monthly Average Yearly
Daily Energy Output Monthly Energy
Months Energy Output Energy Output
(Watt/m2-hr) Output (Watt/m2-hr)
(Watt/m2-hr) (Watt/m2-hr)
July 539.36 16180.8
August 478.575 14357.25
September 539.84 16195.2
November 541.97 16259.1
December 448.54 13456.2
January 476.61 14298.3
February 474.07 14222.1
March 571.06 17131.8
April 717.15 21514.5
15957.25 191487

Figure 2: Daily & Monthly Energy Outputs

108 Journal of the Institute of the Engineering

Table 4: Peak Variation & Possible Plant Rating

Average Peak
Peak Output Average Peak Possible Plant
Months Output for 100 m2
(Watt/m2) 2
Output (Watt/m ) Capacity (KW)
Area(Watt)
July 126.08
August 120.84
September 128.7
November 120.597
December 102.245
January 99.4
February 102.25
March 123.22
April 138.9483
118.03 11803 11

Figure 3: Monthly Peak Variations

Graphs showing diurnal variations of different months (July 2008-April 2009) were drawn. For
demonstration purposes, only diurnal variation for the month of April 2009 is shown (Figure 1).
Graphs for daily and monthly energy outputs are also shown (Figure 2). Daily, monthly and
yearly energy outputs were calculated (Table 3). Using the peak values for the different months
the possible plant capacity was estimated (Table 4). Monthly peak variations were also plotted
(Figure 3). Readings for the month of October 2008 were not available.
Solar photovoltaic generation potential during the period July 2008-April 2009 was assessed for
Birbhum district of West Bengal. It was found that the month of December produced the lowest
solar radiation. Due to the rainy season in the month of July and August radiation levels were
variable in these months. Monthly and yearly outputs were calculated on the basis of 100 m2 area.
Considering the monthly peaks, the average peak output was calculated and an estimate of the
possible plant rating was made.
 Design of A 11 KWp Grid Connected . . . 109

3.2 System Design

Grid connected PV systems can be designed in various ways: with or without batteries, with or
without transformers, etc. Because of short life , large replacement cost and increased installation
cost, batteries are not used in this system. However, a transformer is used for boosting AC output
voltage and feeding to the grid.

Figure 4: 11 KWp Grid Connected Solar Photovoltaic Power Plant

There are two meters connected to the system: the import meter and the export meter (Figure 4).
The difference between the two meter readings gives the power fed to the grid from the solar PV
power plant, making output easy to determine.
From the solar radiation results obtained, a 11 KWp solar photovoltaic power plant can be
developed on a 100 m2 area. Corresponding system sizing and specifications are provided along
with the system design (number of PV modules = 11000/180 = 60). These 60 PV modules can be
accommodated within a 100 m2 area. To ensure appropriate voltage output there are 6 parallel
paths of 10 modules each (system voltage = 24 x 10 = 240V). This 240 volt DC output is the
input of the 3-phase inverter. After the inverter, a 3-phase transformer boosts the AC voltage and
feeds it to the grid. Together, these components make up the complete design layout (Figure 4).

3.3 System Sizing & Specifications

Table 5: The system sizing and specifications for 11 KWp power plant

Grid Specification
No. of Phases Three phase
Voltage rating 400 Volts AC
Frequency 50 Hz.
110 Journal of the Institute of the Engineering

Solar Photovoltaic Power Plant Specification

Plant Capacity 11 KW
Voltage Output 240 Volts dc
Current Output 30.24 A dc
No. of Modules 60 nos.
Area 100m2
Inverter Specification
KVA rating 11.5 - 12 KVA
Input DC voltage 240 Volts DC
Input dc current 30.24 A dc
Output AC voltage 113.136 V ac (phase voltage)
186.96 V ac (line voltage)
No. of Phases Three
Type PWM (for suppressing 3rd harmonics)
Efficiency Almost 90-93%
Total harmonic distortion < 5%
Transformer Specification
KVA rating 12 KVA
No of phases Three
Frequency rating 50 Hz
Primary voltage rating 185 V
Secondary voltage rating 400 V
Primary current rating 45 A + (10-15% extra)
Secondary current rating 58 A + (10-15% extra)
Connections Primary – delta (for suppressing
Secondary – star 3rd harmonics)
10 to 25 taps in secondary
Efficiency Almost 95 %
Extra features Air cooled
Solar Panel Specification
Watt 180 Watt
Voltage 24 Volts
Current 5.04 A
Type polycrystalline
Efficiency 14.3%
Temperature 25 deg c
 Design of A 11 KWp Grid Connected . . . 111

Protection
Protective device 400 Volts under voltage relay

Others: Junction boxes, meters, distribution boxes, wiring, mounting, etc.

Additioally, PWM inverters are used for suppressing the harmonics produced after DC to AC
conversion. The calculation for finding the output voltage of the inverter is:
V ph = 0.4714 × Vdc = 0.4714× 240 = 113.136Volts.
Phase voltage =

Line voltage =
VL = 0.779 × Vdc = 0.779× 240 = 186.96Volts.

4. Conclusions
Solar PV generation potential during the period September 2009-April 2010 was assessed for the
Birbhum district of West Bengal. It was found that the month of December produced the lowest
solar radiation. Monthly and yearly outputs were calculated on the basis of 100 m2 area.
Considering the monthly peaks, the average peak output was calculated and an estimate of the
possible plant rating was made. The methodology adopted seems satisfactory for determining the
possible plant capacity for an arbitrarily chosen area. The design described is based on the solar
radiation measured. System sizing and specifications are provided based on the design made.
Cost analysis of this photovoltaic plant may be performed in the future.

5. Acknowledements
This work is a part of the M.Tech thesis work of Sunanda Sinha, author 2 under the guidance of
Mr. Ratan Kumar Mondal, Lecturer, School of Energy Studies, Jadavpur University, Kolkata.

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