Effect of Temperature on Power Output from Different Commercially available Photovoltaic Modules

P K Dash Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 5, Issue 1( Part 1), January 2015, pp.148-151
www.ijera.com 148 | P a g e
Effect of Temperature on Power Output from Different
Commercially available Photovoltaic Modules
P K Dash*, N C Gupta**
*(Solar Energy Centre, MNRE, Block -14, CGO Complex, New Delhi, 110003,India )
** (School of Environmental Studies, GGSIP University, Dwaraka, New Delhi, 110075,India)
ABSTRACT
Photovoltaic (PV) modules are rated at standard test condition (STC) i.e. at irradiance of 1000 W/m2
,
temperature at 25 0
C and solar spectrum of Air Mass 1.5G. The actual output from the PV module in the field
varies from its rated output due to change in ambient environmental conditions from the STC. The reduction in
output due to temperature is determined by temperature coefficient which varies with the different types of solar
module technologies. In this study, temperature coefficient of different types of commercially available solar
modules is evaluated. The testing has been carried out at PV test facility of Solar Energy Centre, New Delhi.
The modules are selected randomly from various manufactures. It is found that the average temperature
coefficient of power for mono-crystalline, multi-crystalline and CdTe based modules are -0.446 %/°C, -0.387
%/°C and -0.172 %/°C respectively. In case of amorphous silicon module, only one sample is measured and the
temperature coefficient is -0.234 %/°C. This study shows that the temperature coefficient for mono crystalline
silicon module is higher than the other types of solar modules. This study provides an understanding on the
variation in energy generation due to temperature correction between different cell technologies.
Keywords –Solar cell, photovoltaic module, STC, Temperature Coefficient, Power Output.
I. INTRODUCTION
PV module performance is rated under standard
test conditions (STC) i.e. irradiance of 1000 W/m²,
solar spectrum of Air Mass 1.5 and module
temperature at 25°C. Manufacturers of photovoltaic
modules typically provide the ratings at only one
operating condition i.e. STC. However, PV module
operates over a large range of environmental
conditions at the field. So the manufacturer’s
information is not sufficient to determine the actual
performance of the module at field. The suitability
of a PV module technology for a particular site
depends on five major factors which includes annual
solar intensity distribution, variations in the
efficiency of PV module technology with intensity,
annual temperature distribution and module
temperature coefficient, variations in the solar
spectrum distribution and rate of power degradation
of the PV modules with time. The electrical
efficiency of the photovoltaic module depends on
ambient temperature and it reduces when the
temperature increases [1]. Increases in temperature
reduce the band gap of a semiconductor, thereby
effecting most of the semiconductor material
parameters. The decrease in the band gap of a
semiconductor with increasing temperature can be
viewed as increasing the energy of the electrons in
the material [2]. The parameter most affected by an
increase in temperature is the open circuit voltage
[2]. Temperature coefficient indicates how much
will be the decrement in power output if PV module
temperature varies from STC. It is also true that this
temperature coefficient varies from one type of solar
cell technology to another.
Various researchers have done sufficient work to
understand which PV technology will be best
suitable in particular climatic conditions. Ronak et
al. study concluded that amorphous silicon performs
well under Malaysia’s tropical hot and humid
climate, due to favourable constant high solar
radiation in Malaysia and predominant diffuse nature
of solar radiation [3]. Adiyabat et al. analysed the
results of a long-term performance of two different
types of PV module based on actual data measured
over a period of more than six years in the Gobi
Desert of Mongolia [4]. This study observed that the
high output has been achieved due to the operating
condition in an extreme
low ambient temperature and the PV module
degradation rate indicated is only -1.5 %/yr after six
years of exposure test. In summary, this study
showed that a PV module with a
high temperature coefficient, such as crystalline
silicon, is advantageous for use in the Gobi Desert
area [4]. Lim et al. analyzed the temperature effect
on the PV module output and concluded that output
decreases 0.469 %/°C with the temperature variation
when other factors are controlled [5]. Makrides et al.
analysed the effect of temperature on different grid
connected PV technologies installed in Cyprus. The
results showed that over the evaluation period the
RESEARCH ARTICLE OPEN ACCESS

highest average thermal losses in annual DC energy
yield were 8% for mono crystalline silicon and 9%
for multi crystalline silicon technologies while for
thin film technologies, the average losses were 5%
[6]. Skoplaki and Palyvos observed that the
operating temperature plays a pivotal role in the
photovoltaic conversion process. Both the electrical
efficiency and hence the power output of a PV
module depends linearly on the operating
temperature and decreases with cell temperature [7].
George et al. evaluated the temperature behaviour of
13 different types of PV modules, which had been
exposed to real conditions in Stuttgart, Germany and
Nicosia, Cyprus. The temperature coefficient for
mono crystalline, multi crystalline and amorphous
silicon varied -0.353 to -0.456 %/0
C, -0.403 to -
0.502 %/0
C and -0.039 to - 0.461%/0
C respectively
[8]. Minemoto et al. analysed the impact of spectral
irradiance distribution and temperature on the
outdoor performance of amorphous silicon and multi
crystalline silicon modules and concluded that
the output energy of amorphous silicon modules
mainly depends on spectrum distribution and is
higher under blue-rich spectrum. In contrast,
the output energy of mono crystalline
silicon module is sensitive to module
temperature but not to spectrum distribution [9].
Kalogirou and Tripanagnostopoulos showed that for
mono crystalline and poly crystalline silicon solar
cells, the efficiency decreases by about 0.45% for
every degree rise in temperature, while for
amorphous silicon cells, the effect is less, with a
decrease of about 0.25% per degree rise in
temperature [10]. Vokas et al. showed the electrical
efficiency of the photovoltaic panel depends on its
temperature and it reduces when the temperature
increases [1]. Nelson concluded that the low
temperature operation is necessary for PV modules.
As temperature is increased, the dark saturation
current of the PV cell increases which leads to a
decrease in open circuit voltage. Also, the band gap
of the photovoltaic material decreases which leads to
an increase in photocurrent. The first effect is more
dominant than the second effect and thus there is a
net decrease in the solar conversion efficiency with
increasing temperature [2]. Nishioka et al. analysed
field test data from a 50 kW PV system installed at
Japan. It is found that the PV system operated in a
wide temperature range and was strongly affected by
the temperature coefficient on conversion efficiency
when the module temperature became high. The
results showed that annual output energy of the PV
system increased about 1% by an improvement of
0.1%/°C in the temperature coefficient [11].
Jawaharlal Nehru National Solar Mission is a major
initiative of the Government of India to promote
solar energy while addressing India’s energy
security challenges [12]. The mission has set an
ambitious target of deploying 20 GW of grid
connected solar power by 2022 in the country. The
installed capacity of grid interactive PV based
electricity is 1648 MW as on 31st
March 2013[12].
Hence it is important to understand the performance
of modules at different ambient temperature of the
country. In this study temperature coefficient of
different types of commercially available solar
modules are evaluated. The testing has been carried
out at PV test facility of Solar Energy Centre, New
Delhi. The modules are selected randomly from
various manufactures.
II. EXPERIMENTS
Temperature coefficients for different type of
PV technologies are evaluated at the test facility
established at Solar Energy Centre (SEC), New
Delhi for testing of modules under indoor laboratory
conditions. Figure1and 2 represents the large area
(2m × 2m) single pulse sun simulator (Model:
QuickSun 700A, Endeas, Finland) and
environmental test chamber (Model: BSC-ETC
1000, Make: Tenny incorporation USA). The
temperature of the module is increased at
environmental test chamber. Once the module has
reached the desired temperature, short circuit
current, open circuit voltage and power output are
measured. The module temperature has varied in
steps of approximately 5°C over a range of interest
and kept for 30 °C before the measurements.
Different types of module from various
manufacturers are tested which are selected
randomly. The module rated capacity varies from 3
Wp to 300 Wp. Four different solar cell technologies
i.e. single crystalline silicon, multi crystalline
silicon; amorphous silicon and CdTe are used for
evaluation of temperature coefficient. The
temperature coefficient is determined according to
IEC 61215 and 61646 standards at an irradiance of
1000 W/m2 [13,14]. The experimental
measurements of short circuit current with respect to
various temperature are plotted and the least square
fit curve is obtained. The slope of this least square fit
curve divided by the short circuit current at 25°C is
the temperature coefficient for current for this
particular module. Similar kinds of experiments are
conducted for open circuit voltage and power for
evaluation of temperature coefficients for open
circuit voltage and power respectively.

Figure 1 QuickSun 700A large area solar simulator
Figure 2 Environmental test chambers.
III. Results and Discussion
The temperature coefficient for short circuit
current, open circuit voltage and power are evaluated
for mono crystalline silicon, multi crystalline silicon,
amorphous silicon and CdTe based solar modules.
Figure 3-5 represent the variations in current,
voltage and power with respect to temperature for a
mono crystalline silicon module of 10 Wp rated
capacity. Similar kinds of profiles are obtained for
different rated capacity modules and also for
different types of module technologies. It can be
observed from these Figures that a linear best fitted
straight line has been drawn based on the
experimental measurements. The temperature
coefficient is the slope of this best fitted straight line
divided by the value of that parameter at 25°C. In
similar fashion, the temperature coefficients are
evaluated for different module technologies. Table 1
represents the average temperature coefficients of
power for mono crystalline silicon, multi crystalline
silicon, amorphous silicon and CdTe respectively.
The temperature coefficient of power in mono
crystalline silicon varies from -0.394%/°C to -
0.483%/°C with an average of -0.446%/°C. In case
of multi crystalline silicon, it varies from-0.329%/°C
to -0.506%/°C with an average of -0.387 %/°C. In
case of CdTe, only two samples are measured with
values -0.168%/°C and 0.176%/°C and an average of
-0.172%/°C. In case of amorphous silicon module,
only one sample is measured and the temperature
coefficient is -0.234%/°C. It is found from the study
that the average temperature coefficient of power for
CdTe technology is minimum (-0.17%/°C) and
maximum for mono crystalline silicon module (-
0.446%/°C). It also can be concluded that CdTe
module will perform better in high ambient
temperature region in compare to other types of
modules.
Figure 3 Temperature coefficient of short circuit current
(mono C-Si sample : 10Wp)
Figure 4 Temperature coefficient of open circuit voltage
(mono C-Si sample : 10Wp)
Figure 5 Temperature coefficient of power (mono C-Si sample:
10Wp)

Table 1 Temperature coefficient for different PV module
technologies
Type
of PV
modul
e
Modul
e peak
output
(Wp)
Temperature coefficient
(%/°C)
Average
temperatu
re
coefficien
t of
power
(%/°C)
curren
t
voltag
e
Power
Mono
C-Si
10 0.044 -0.337 -0.440 -0.446
74 0.025 -0.336 -0.479
40 0.034 -0.336 -0.455
75 0.037 -0.323 -0.428
12 0.029 -0.359 -0.483
12 0.027 -0.295 -0.394
Multi
C-Si
75 0.031 -0.267 -0.356 -0.387
75 0.059 -0.369 -0.506
12 0.036 -0.291 -0.373
50 0.046 -0.264 -0.346
50 0.033 -0.291 -0.396
300 0.054 -0.306 -0.428
75 0.001 -0.058 -0.329
75 0.002 -0.075 -0.364
a-Si 3 0.098 -0.294 -0.234 -0.234
CdTe
80 0.071 -0.28 -0.176 -0.172
80 0.034 -0.197 -0.168
IV. Conclusion
This work helps in understanding the variation
in output from a particular PV technology due to
variation in operating temperature only. It is found
from the analysis that CdTe photovoltaic modules
seems to be better option in hot climates considering
the temperature loss to be minimum due to low
temperature coefficient. This study is planned to
extend for generating data with more number of
modules to predict the trend of temperature
coefficient of power with respect to different rated
module of a particular technology in the different
climatic zones of India. It is important to have a
technology mapping based on energy yield for each
PV technology for different climatic zones so as to
get maximum possible return from the project
investment.
ACKNOWLEDGEMENTS
The authors sincerely acknowledge the
contribution of National Institute of Solar Energy
(formerly known as Solar Energy Centre) for
providing the experimental facility to carry out the
above research work..
REFERENCES
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photovoltaic thermal systems for domestic
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[3] Ronak D, Adnan I, Goh LJ, Ruslan MH,
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Accessed on 15 May, 2013.
[13] IEC 61215:2005 International Standard
Crystalline Silicon Terrestrial Photovoltaic
Modules- Design Qualification and type
approval.
[14] IEC 61646: International Standard Thin Film
Terrestrial Photovoltaic Modules- Design
Qualification and type approval.

Effect of Temperature on Power Output from Different Commercially available Photovoltaic Modules

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