Analysis of PV Module Performance and Temperature Coefficient

This report examines the realistic performance of photovoltaic (PV) modules in relation to temperature coefficients. It reviews temperature data from 2016, focusing on poly-PV and mono-PV modules, along with ambient temperature data. The study investigates how the operating temperature coefficient affects the performance and efficiency of the system in harvesting solar energy, considering factors like module type and solar intensity. The report details the technical preparation, including apparatus, procedures for natural sunlight calibration, and solar simulator tests. Results and observations, including graphical representations, demonstrate the inverse relationship between temperature and solar radiation, impacting parameters such as open-circuit voltage and short-circuit current. The study also presents relevant equations and analyses the impact of temperature on PV unit efficiency, providing insights into the optimal operating conditions for PV modules in desert climates. The report concludes with acknowledgements and references.

Realistic Behavior of PV Module Performance
Related to Temperature Coefficient Test
List of Authors, Affiliation, Country (s)
Abstract- The renewable energy sources are taking root
in many economies owing to the infinite merits that they
bring on board. The PV modules are used to harvest
solar energy during sunny seasons. In Saudi Arabia,
especially, the summer period guarantees an excellent
harvest. Unfortunately, the climatic conditions
surrounding the PV modules and cells affect the
performance and efficiency of the system in harvesting
solar energy. It is based on the output obtained as peak
power. The designers have run several models to test for
the most suitable operating temperature coefficient. A
positive temperature coefficient, in this case, is obtained
for the model with a short circuit implementation.
When compared to the actual results obtained from the
PV modules, the voltage behavior is the same.
Keywords: PV module, performance, solar radiation,
operating temperature coefficient.
I. NOMENCLATURE
AM Air Mass
OTC Operating Temperature Coefficient
Isc Short circuit Current [A]
Impp Maximum power point current [A]
Irr Solar radiation [W/m2]
NOCT Nominal operating cell
temperature
PV Photovoltaic
STC Standard test condition
T Temperature [0C]
Vmpp Maximum power point voltage [V]
Voc Open Circuit Voltage [V]
II. INTRODUCTION
This paper seeks to review the realistic
temperature data from year 2016 based on the poly-
PV, mono-PV, and ambient temperature data. The
operating temperature coefficient that affects the
encapsulating material, thermal attributes of the
module such as assimilation and indulgence
properties. Other factors that affect the OTC are such
as the different types of modules as poly-PV or
mono-PV modules, levels of solar intensity and the
presence of ambient temperature alongside the wind
velocity [1]. This paper seeks to determine the
operating temperature of the PV module [2]. The
determination of the operating temperature ensures
that the system can be evaluated for its performance,
power output, and system efficiency. Saudi Arabia
experiences extreme desert climate and sandstorms.
The Rub ‘al-Khali’ or empty quarter is a vast desert
which has continuous sand and very arid
environment. The region experiences less than 7” of
rainfall per year with no permanent streams [3]. The
summer temperatures reach the extremes of 130F in
some areas of the country.
III. TECHNICAL WORK PREPARATION
The process involves the installation of the module to
collect electrical performance data and climatic
conditions over a specified period [4].

Aims & Objectives
(i) To determine scale of the required
operating temperature for the desert
climate setup.
(ii) To determine the values of short-circuit
current, open-circuit voltage, and
maximum peak of the PV modules in
the test.
Apparatus
(i) A radiant source.
(ii) A PV module reference gadget; it
should have Isc against the solar
intensity levels or attributes well
calibrated using the radiometer. The
calibration is guided by the IEC 60904-
2 or IEC 60904-6.
(iii) Temperature changing equipment.
Focus on the test items within a given
interest range.
(iv) A mounting system that can support the
test items as well as the devices used for
reference in the same plane or at
perpendicular scales.
(v) A monitoring system for the test
specimen and the reference devices
used in the procedure or model.
(vi) Equipment to measure the current and
voltage of the test specimen and
reference. Accuracy expected in the
confines of ± 0.2 %of the reading.
Procedure
Part 1: natural sunlight
(i) The reference device was mounted co-
planar with the test module such that
both were normal to the direct solar
beam. The necessary instrumentation
was connected.
(ii) The test controls at the desired level
were set, and the test module and
reference device were equipped with
temperature controls.
(iii) The measurements in natural sunlight
were taken when the cumulative solar
light intensity is obtained on the
maximum scale. The solar intensity
may vary as a result of temporary
oscillations which may be caused by
cloudy areas, haze or smoke. The wind
velocity is expected to be quite low at
such a point.
(iv) The current-voltage characteristics and
temperature of the test samples were
recorded concomitantly with the data of
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the short-circuit current and reference
device temperature at the desired
temperature levels.
(v) The irradiance Go was computed
according to the IEC 60891 from the
measured current of the PV orientation
device at the anticipated temperatures as
well as its calibration value at STC.
Part 2: solar simulator
(i) The test module instruments used in the
alteration of temperature values is
mounted alongside the PV module
reference device.
(ii) The solar intensity or radiation is
determined to ensure that the test model
develops the short-circuit current of the
sample. The irradiance setting was set
to maintain the irradiance setting
throughout the test.
(iii) Measurement were taken once the
module was heated and cooled to the
desired temperature. The Isc, Voc, and
peak power were measured. The unit
temperature was adjusted in stages of 5
degrees Celsius over a range of
concentration of at least 30 degrees
Celsius. The data obtained were
recorded in a table.
Results and Observations
G0= 1000 Wm
−2 x I sc
Irc
x [1−αrc ( Tm −250 C ) ]
α rc=relative temperature coefficient [ 10 C−1 ] at 250 C
¿ 1000 W /m2
The temperature coefficient test results for the 60-cell
poly-PV modules. The PV module used in this
technical experiment has the following information,
Module FU 255 P
Module Power (Pmax) 255 W
Maximum power voltage
(Vmpp)
35.0 V
Maximum power current
(Impp)
7.29 A
Open Circuit Voltage (Voc) 43.2 V
Short Circuit Current (Isc) 8.10A
Maximum system voltage 1000 VDC
NOCT (Nominal Operating
Cell Temperature)
45 2 C
Standard Test Conditions STC: 1000 W/sqm -AM
1.5 -250 C
The temperature coefficient test results for the 60-cell
mono-PV modules. The PV module used in this
technical experiment has the following information,
Module FU 265 M
Module Power (Pmax) 265 W
Maximum power voltage
(Vmpp)
35.5 V
Maximum power current
(Impp)
7.46 A
Open Circuit Voltage (Voc) 43.3 V
Short Circuit Current (Isc) 8.25 A
Maximum system voltage 1000 VDC
NOCT (Nominal Operating
Cell Temperature)
45 2 C
Standard Test Conditions STC: 1000 W/sqm -AM
2

1.5 -250 C
Discussion
Jan-16
Feb-16
Mar-16
Apr-16
May-16
Jun-16
Jul-16
Aug-16
Sep-16
Oct-16
Nov-16
Dec-16
0
10
20
30
40
50
60
70
Temperature Behaviour of PV
Module
Mono-PV Temp Poly-PV Temp
Ambient Temp
Year 2016
Temp (0 C)
For the poly-PV module,
0:01:24 4:15:11 8:28:55 12:42:39 16:56:23 21:10:07
0
10
20
30
40
50
60
70
poly-PV Temp
poly-PV Temp
For the mono-PV module,
0:01:24 12:02:17
0
20
40
60
Plot of Mono-PV module
Mono-PV Temp
Full Day (HH:MM:SS)
Temperature (0 C)
The module used in this paper is obtained from 2016.
Based on the model, a correlation of the photovoltaic
operating temperature is obtained as,
T c=T a+ G
α +βW +γ . ln (1+
( V
V mpp , panel ( G ,T c ) ) )
W- wind speed (m/s)
To obtain the numerical values of α , β∧γ
parameters and three constants.
The PV unit’s efficiency is given using the OTC and
isolation factor, G as,
η=ηref [1−X ( T c−25 ) + ε log10 ( G
Gref ) ]
The PV module cells which desire to analyze the
open circuit voltage tend to have a negative
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temperature coefficient. An increase in temperature
results in a posse gap of the integrated
semiconductor. On the other hand, it has a confident
temperature coefficient for the short-circuit cases.
The system requires lowering of the operating
temperature of the modules but with high irradiance.
A larger PV current causes a rise in the short circuit
current on the set solar isolation value. The graphical
illustrations show that there is a decrease in the
operating temperature of the modules as the solar
radiation increases [5]. The solar radiation is
measured regarding temperature increase or
decreases respectively. An increase in the
temperature results in a decreased Voc and an
increased Isc.
V =
V oc∗
( ln ( k −
( I
I sc )
N
) )
lnk −Rs ( I−I sc )
1+ Rs I sc
V oc
Where the,
Rs=V oc−V mp
Imp
N= ln ( k−ka )
ln ( I mp
I sc )
a=
V mp ( 1+
( Rs ISc
V oc )+Rs ( I mp−Isc ) )
V oc
at {k =8.08 I < IMPP
k=2.00 I ≥ IMPP
APPENDIX
Modelling a practical PV
The current readings and power ratings can be
derived the results. The trend based on the data
obtained throughout the year is quite close to the
testing coefficient.
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ACKNOWLEDGEMENT
The authors of this report cordially wish to
acknowledge the contributions of (list all the people
to be recognized here) for their research studies on
renewable resources and systems and their
implementation and practical performance.
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