ELEC1302: Solar Laboratory Page 1 2009
School of Electrical, Electronic and Computer
The University of Western Australia
Power and Machines Technologies
Laboratory Notes: Solar Cell Characterisation
Dr. J. Henry
ELEC1302: Solar Laboratory Page 2 2009
Laboratory report format and assessment
Please note that a web-based on-line laboratory report writing tool should be used for
This tool can be obtained at a later date (probably around 1st September 2009, you will
be informed via email and in lectures). You should print out a hard copy of the
laboratory for handing in along with a blue assignment sheet cover sheet and your
original results that you obtained in the laboratory session.
As a general guideline, the marking key is as follows:
Aim (1 mark)
Apparatus: refer to laboratory instructions. You should include a note on which set of
equipment you used.
Procedure: refer to laboratory instructions
Treatment of results (6 marks): Tabulate results where possible. Hint: Put your results
into an Excel spreadsheet (or similar) to help you with data processing.
Conclusions (2 marks): Answer the Aim!
Discussion (2 marks): Concise sentences commenting on errors, implications of results.
Presentation (2 marks)
Clarity of Explanations (2 marks)
• You should also attach the handwritten results that you obtained in the laboratory – so
this would be the hand-written results obtained WHILE YOU DID the laboratory. (If not
included: -2 marks)
• Ensure that you REFERENCE any resources that you use.
• The laboratory report will be due Thursday October 8th at 12noon and should be
handed in to the wooden assignment boxes on the first floor of the EE building. Late
laboratory reports will attract a 10% deduction for each working day that it is late. Marks
for reports will be sent out via email.
• A “blue” assignment cover sheet must be filled out, signed and attached. Reports
without this will not be marked and a mark of zero will be assigned.
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ELEC1302: Solar Energy Laboratory Experiment.
Solar Module SEA005 of 31cm2 area
50 Watt bench lamp
Daystar light meter
2 digital multimeters
Decade resistance box
dc power supply
Shielding box for dark measurements
Set of stackable leads - 8
Part 1: Measurement of light V-I characteristic of solar panel.
1) Connect the light source to the dimmer.
2) Switch on light source with the dimmer set fully clockwise to warm up.
3) Set the distance of the light source to the measuring surface of the light meter to
4) Determine where on the dimmer scale 1 sun (100 mW/cm2) lies, 0.5 suns (50
mW/cm2) and 0.25 suns (25 mW/cm2). Note these values.
5) Set the dimmer so as to produce 0.25 suns on the solar panel. You will need to
adjust the height of the lamp to be 14 cm above the face of the solar panel.
6) Set up the circuit as shown below.
V1 solar panel variable resistor
Note: A voltmeter in parallel with a shunt resistor is used instead of an ammeter to
produce a more accurate set of measurements. An ammeter has a small resistance
associated with it and so will lead to inaccuracy in the high current part of the V-I
7) Take readings of VOC and ISC.
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8) Varying the values of the variable resistor from 1! to 104! noting the values of
V1 and V2. Take around 20 readings concentrating about half the readings around
the high current/low resistance range. The maximum power point will occur
around this region of the V-I characteristic. Try to take readings briskly as the
characteristic of the solar panel changes as the panel heats up. If the panel is
heating up too much place the cover between the light source and the solar panel
and allow the panel to cool for a short period.
9) Allow the solar panel to cool for 5 minutes
10) Repeat Steps 1-9 for 0.5 suns.
11) Repeat Steps 1-9 for 1 sun.
Part 2: Measurement of dark V-I characteristic of solar panel.
1) Set up the circuit as shown below. Ensure that you start by connecting the
positive side of the solar cell (red terminal) to the positive side of the power
supply. This will ensure that the solar panel is forward biased.
V solar panel A
2) Cover the solar panel with a box so that there is no light induced effects while
measuring the V-I characteristic.
3) Vary the voltage on the power supply in approximately 250mV steps between 0V
and 3.5V, noting the value of current. Warning: Excessive bias voltages will
destroy the module.
4) Reverse the leads at the power supply ie put the red lead into the negative
terminal of the power supply. The solar panel will be reverse biased.
5) Repeat step 3.
Treatment of results:
Part 1: Light V-I Characteristics
1) Compare the values of VOC and ISC for 0.25, 0.5 and 1 sun. Comment on any
relationship between the voltage values (eg linear decrease, etc). Comment also
on the relationship between the current values.
2) Plot the light V-I characteristics from 0.25, 0.5 and 1 sun on the SAME GRAPH.
3) From your graph, or V-I data, calculate the i) maximum power point ii) fill factor,
iii) efficiency for 0.25 sun. The maximum power point PMAX can be obtained
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from the product V × I for your measurements. This will occur around the "knee"
region of the curve when graphed. Knowing the input power and the cell area,
calculate the efficiency of the panel for each of the intensity levels.
4) Repeat 3 for 0.5 and 1 sun.
5) Compare the values of maximum power point, fill factor and efficiency for 0.25,
0.5 and 1 sun.
6) From the shape of the graphs found in 2, try to determine whether the solar panel
has a good/poor shunt resistance or a good/poor series resistance.
Part 2: Dark V-I Characteristics
1) From the forward biased dark V-I characteristics, plot V-ln I. From this plot
determine an estimate of the SERIES resistance. (See Point 5 in the Appendices)
2) Plot the reverse biased dark V-I characteristic and determine the SHUNT
resistance from the gradient of the plot.
3) Comment on whether the results from 2 agree with your inferences from the light
Conclusions: Summarise the main points from your results.
Write brief notes on the following points:
1) Efficiency and maximum power and incident light level
2) Variation with light input (problems of cloudy days, dawn/dusk) and need for
3) The magnitudes of the shunt and series resistances and their effects on cell
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Appendix: Further notes on solar cells
1) Circuit Model of a solar cell
2) V-I characteristics
Jlight Light Char
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3) Effect of Series and Shunt resistance on illuminated V-I Characteristic
4) • Fill Factor is the squareness of the output characteristics and is usually around
0.7 to 0.8 for reasonable cells.
maximum electrical power out
input optical power
P Imp Vmp
= max =
Imp Vmp Isc Voc
Isc V P
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5) Obtaining the Series Resistance from the DARK V-I characteristic.
From your dark V-I results, plot the ln I versus V. Use mA and mV respectively.
Your curve should look like the one given below.
ln I (mA) Line 1
- Draw a line similar to the one shown (Line 1).
- Draw a horizontal line which intersects with Line 1 and the lnI-V characteristic (Line
2). Take this line back to the vertical axis – antilog the value of lnI1 – this gives you’re
an I value.
- Next calculate ΔV as indicated on the diagram.
- Use the following to calculate Rs: R s =
Note: You may find your diagram looks like the one below, draw Line 1 as shown and
follow same instructions as above. This lnI-V characteristic indicates a large series
ln I (mA) Line 1