IJERD – International Journal of Environmental and Rural Development (2019) 10-2

Research articleerd

Performance Analysis of 325 kW Solar PV Rooftop System
Using PVsyst Program
PAKAYKAEW BOOTTARAJA
Faculty of Science and Engineering, Kasetsart University, Chalermphrakiat Sakonnakhon
Province Campus, Sakonnakhon, Thailand

NAPAPORN PHUANGPORNPITAK*
Faculty of Science and Engineering, Kasetsart University, Chalermphrakiat Sakonnakhon
Province Campus, Sakonnakhon, Thailand
Email: napaporn.ph@ku.ac.th
Received 19 December 2018

Accepted 15 August 2019(*Corresponding Author)

Abstract The power demand of electricity growing very fast with high concern of climatechange and environmental constrains. According to the Thailand Power Development Plan
2015 (PDP 2015) starting from 2015 to 2036, the national target of 30% of renewableenergy to total energy consumption by 2036 is to be achieved. Solar photovoltaic (PV) is
an important option makes the PDP 2015 meets the target. This paper aims to present theperformance analysis of the solar PV rooftop system installed at Sakon Nakhon Rajabhat
University. The system consisted of 1,016 polycrystalline silicon PV modules coupled to13 units of 25 kW grid tied inverter. This system will be installed at the rooftop of the threebuildings namely, the Central Building (CB), the Engineering Technology Building (ETB)
and the Multipurpose Building (MB). The PV rooftop system is designed using PVsyst
program. The PV modules faced tilts and azimuths with 5°/31°, 10°/31° and 5°/16°,respectively. The simulation results indicated that solar PV rooftop system can produce
452.92 MWh/year. The solar PV rooftop system could produce electricity generating from06.00 - 18.00. The performance ratio of the system is 0.74. The Central Building has
maximum power electricity generating as 44.44%. The Engineering Technology Building
has high performance ratio because of its tilts and azimuths of solar panels that affect theirradiation. The solar PV rooftop can reduce the peak demand in time 06.00-18.00 of
13.24% and the reduction of greenhouse gas emissions is 263.65 tco2/year.
Keywords climate change, photovoltaic, PVsyst (PV system design program), renewableenergy, solar PV rooftop system, sustainable development

INTRODUCTION
Solar photovoltaic (PV) is now widely used for power generation worldwide. According to theAlternative Energy Development Plan (AEDP 2015-2036), the renewable energy is targeted for
30% of total energy consumption in Thailand. Due to its cost competitive and high potential ofsolar energy in the country, solar power has been promoted and scheduled to be installed at 6,000
MW by 2036 (Tanatvanit, 2003 and Chimres, 2016). Sakon Nakhon Rajabhat University (SNRU)
is an academic institute in Sakonnakhon province which located in the northeastern part ofThailand. Sakon Nakhon Rajabhat University has an area of 1.02 km² and there are 50 buildings.
This institute has high energy consumption. The electricity cost per year is 20 million baht. Theenergy block grant project subsidized from the Ministry of Energy is launched in 2018 for the 325
kW solar PV rooftop to promote the use of renewable energy in the institute.

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IJERD – International Journal of Environmental and Rural Development (2019) 10-2

OBJECTIVE
This work was aimed to present the performance analysis of the 325 kW solar PV rooftop. ThePVsyst program was employed as a tool to investigate the technical performance assessment,
project design and its simulation. The three proposed buildings will be launched in 2020. This
study would be useful to predict the performance of the system, financial analysis and the user
perspective on a solar PV rooftop system. The study clearly illustrates the potential to use the PV
rooftop system to supply basic energy services that is desired in academic building settings.
MATERIALS AND METHODS
The installation of solar PV rooftop system at the Central Building (CB), the Engineering
Technology Building (ETB) and the Multipurpose Building (MB) is shown in Fig. 1.

Fig. 1 Research site
Figure 2 shows layout of the solar PV rooftop system. The solar PV rooftop system consists ofthe following components:

Polycrystalline silicon PV 320 Wp (1,016 modules)
Grid tied inverter 25 kWac (13 units)
Monitoring system
Cable wiringFig. 2 Layout of solar PV rooftop systemⒸ ISERD

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IJERD – International Journal of Environmental and Rural Development (2019) 10-2

PVsyst Program
The PVsyst program is one of the energy modeling tools. It can show the useful results of solar PV
system including the produced power and the occurred losses in the system (Mermoud, 2014 andBoughamrane, 2016). The location site, setting tilt and azimuth, PV module and inverter
specifications are the required information for the program as shown in Fig. 3.

Fig. 3 PVsyst program
Technical Performance Assessment
The parameters for performance analysis of solar PV rooftop system followed by IEC 61724 areshown in Table 1 (Kumar, 2017 and Gurupira, 2017). The following nine parameters are used toanalyze the performance of the system: the reference yield (Yr), the array yield (Ya), the final yield(Yf), the array capture losses (LC), the system losses (LS), the performance ratio (PR), the arrayefficiency (ηa), the system efficiency (ηsys) and the capacity utilization factor (CUF) (Kumar, 2017
and Yadav, 2018).
Table 1 Equation for technical performance assessment
Parameter
Yr
Ya
YfLCLSPRηaηsys
CUF

Equation
Ht/Go
EDC/Po
EAC/PoYr - Ya
Ya - Y f
Yf/ Yr
EDC/(Aa Ht) x 100
EAC/(Aa Ht) x 100
EAC/(Po24365)x100

Unit
kWh/kWp/day
kWh/kWp/day
kWh/kWp/day
kWh/kWp/day
kWh/kWp/day%%%

Ht = Total irradiance at the standard test condition (kWh/m2/day)
Go = Global irradiance at the standard test condition (kWh/m2/day)
EDC = DC energy of the PV system (kWh)EAC = AC energy of the PV system (kWh)Po = Nominal power of the PV array at the standard test condition (kW p)
Aa = Array area (m2)

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IJERD – International Journal of Environmental and Rural Development (2019) 10-2

Project Design and Simulation
Table 2 shows the description of PV system installation in three buildings: CB, ETB and MB. The
Central Building has the maximum roof areas for PV installation, followed by the Multipurpose
Building and the Engineering Technology Building.
Table 2 Description of PV rooftop system
Description
Location
Structure building
Roof area
Tilt/Azimuth
PV modules (320Wp)
PV modules area
No. of PV modules (set 1)

CB
17.18° N, 104.08° E
Metal sheet
1,643.35 m2
5°/31°
454 modules
888 m2
series=18modules
parallel=21 strings
series =19 modules
parallel=4 strings
6 unit145.28 kWp

No. of PV modules (set 2)
Grid-tied inverter (25 kW)
Total PV power

ETB
17.18° N, 104.08° E
Metal sheet
924.42 m2
10°/31°220 modules
430 m2
series =18 modules
parallel=8 strings
series =19 modules
parallel=4 strings
3 unit70.40 kWpMB17.18° N, 104.08° EMetal sheet
1,323.60 m2
5°/16°
342 modules
669 m2
series =18 modules
parallel=19 strings

4 unit109.44 kWp

RESULTS AND DISCUSSION
Table 3 depicts the monthly average energy injected into grid, global incident, greenhouse gas
emissions and performance ratio. Among three buildings, the Engineering Technology Building
has slightly high performance ratio than other buildings as 0.743 because of its tilts and azimuths ofsolar panels that affect the irradiation.
Table 3 Monthly average energy inject to gridMonthJanFebMar
AprMayJunJulAugSepOctNovDecYear

E-grid
(MWh)
17.94
16.00
18.22
17.79
17.72
16.82
16.26
15.43
14.30
17.04
16.35
17.44
201.30CB
Global(kWh/m2)
163.5
147.0
170.1
167.3
166.9
156.5
151.8
143.5
132.8
158.4
150.4
159.1
1867.4CO2(tco2)
10.44
9.31
10.61
10.36
10.31
9.79
9.46
8.98
8.32
9.92
9.52
10.15
117.18

PR
0.755
0.749
0.737
0.732
0.731
0.740
0.737
0.740
0.741
0.740
0.748
0.754
0.742

E-grid
(MWh)
9.114
7.992
8.967
8.591
8.435
7.996
7.745
7.413
6.968
8.4408.263
8.926
98.848ETB
Global(kWh/m2)
171.3
151.4
172.6
166.6
163.9
153.4
149.1
142.1
133.4
161.8
156.7
167.8
1890.2CO2(tco2)
5.31
4.65
5.22
5.00
4.91
4.65
4.51
4.32
4.06
4.91
4.81
5.20
57.54

PR
0.756
0.750
0.738
0.732
0.731
0.740
0.738
0.741
0.742
0.741
0.749
0.756
0.743

E-grid
(MWh)
13.62
12.10
13.75
13.42
13.35
12.65
12.25
11.63
10.80
12.88
12.38
13.24
152.07

MB
Global(kWh/m2)
164.7
147.6
170.3
167.5
166.9
156.3
151.7
143.6
133.1
158.9
151.1
160.3
1872.0CO2(tco2)
7.93
7.04
8.00
7.81
7.77
7.36
7.13
6.77
6.29
7.50
7.21
7.71
88.52

PR
0.756
0.749
0.737
0.732
0.731
0.740
0.738
0.740
0.742
0.741
0.748
0.755
0.742

Table 4 shows the results of overall system, it depicts monthly average energy injected intogrid, global incident, greenhouse gas emissions, performance ratio, energy saving analysis andeconomics. The solar PV rooftop can reduce power consumption by 452.92 MWh/year.
Figure 4 shows the normalized PV production, i.e. the collection losses (LC) is 1.23
kWh/kWp/day, the system losses (LS) is 0.09 kWh/kWp/day and the produced useful energy (Yf) is3.82 kWh/kWp/day. Figure 5 presents the performance ratio of the overall system for each month.
The highest performance ratio is 0.76 in January and December. The lowest performance ratio is0.73 in May. The performance ratio is slightly different in each month with the average
performance ratio of the system is 0.74.
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IJERD – International Journal of Environmental and Rural Development (2019) 10-2

Table 4 Results analysis of the 325 kW solar PV rooftop systemMonthE-grid(MWh)

JanFebMar
AprMayJunJulAug
SepOct
Nov
Dec
Year

40.73
36.15
41.00
39.87
39.56
37.52
36.31
34.53
32.12
38.42
37.05
39.67
452.92

Solar PV rooftop 325 kW
GlobalCO2(kWh/m2)(tco2)
165.6
148.1
170.7
167.2
166.2
155.8
151.2
143.2
133.0
159.3
152.0
161.4
1873.9

23.71
21.04
23.87
23.21
23.03
21.84
21.14
20.10
18.70
22.36
21.57
23.09
263.65

PR

Energy demand
06.00 – 18.00
24 hr
(MWh)
(MWh)

0.75
0.75
0.74
0.73
0.730.74
0.74
0.74
0.74
0.74
0.75
0.75
0.74

241.07210.79323.89295.75289.59274.01
326.00361.17379.70308.30229.92180.253,420.44437.08329.45463.39427.83418.68397.10459.04475.79540.59451.72352.73298.53
5,051.92

Energy conservation
Save
Save
06.00 – 18.00 24 hr
(%)
(%)
16.90
9.32
17.15
10.97
12.66
8.85
13.48
9.32
13.66
9.45
13.69
9.45
11.14
7.91
9.56
7.26
8.46
5.94
12.46
8.51
16.11
10.50
22.01
13.29
13.24
8.96

*** Emission factor = 0.58, Average electricity cost of SNRU = 4.39 Bath/kWh

Fig. 4 Normalized PV production

Fig. 5 Performance ratio

Fig. 6 Loss diagramⒸ ISERD

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Economic(Bath)
178,804.70
158,698.50
179,990.00
175,029.30
173,668.40
164,712.80
159,400.90
151,586.70
141,006.80
168,663.80
162,649.50
174,151.30
1,988,362.70

IJERD – International Journal of Environmental and Rural Development (2019) 10-2

Figure 6 presents the loss diagram of the system. The array nominal energy at standard test
condition (STC) is 570.5 MWh, the array virtual energy at maximum power point (MPP) is 463.7
MWh. The available energy at the inverter output after the inverter loss was extracted would be theenergy injected into the grid is 452.9 MWh. The produced electricity from the solar rooftop systemdecreases during May to September due to the rainy season in Thailand.
CONCLUSION
The solar PV rooftop system is designed using PVsyst program as a tool. The system is planned to
be installed on the roofs of three buildings: the Central Building, the Engineering Technology
Building and the Multipurpose Building at the academic institute which located in the northeasternpart of Thailand. The Central Building can generated maximum power electricity of 201.30
MWh/year or 44.44% of the total system. The electricity produced during the sun rises (06.0018.00). The solar PV rooftop system can reduce the peak demand of electricity as 452.92
MWh/year or 13.24%/year during daytime (06.00-18.00). The generated electricity from solar PV
energy can reduce the use of electricity by 8.96%/year. The system can save electricity costthroughout the year as 1.98 million baht/year and the reduction of greenhouse gas emissions isequaled to 263.65 tCO2/year.
ACKNOWLEDGEMENTS
The authors are thankful to Sakon Nakhon Rajabhat University for project information support.
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