Solar Cell Prac 1
Stage 1 Physics
Solar Cell Practical Investigation
Name:
Noah Nishihara
Home Group:
E05
Report
of experiment on:
The
Performance of APolycrystalline Solar Cell In Varying Temperatures
Completion Date
of Experiment: Monday, June 05, 2017
Work Finalised: Wednesday,
June 14, 2017
Table of Contents
Background
Solar cells are becoming widely known asthe awareness of
environment and energy issues increases. They are made with semiconductors and can
change light energy directly into electricity. The photovoltaic effect causes
electrons to become excited and move when sunlight hits the cell. This is
useful when p-type semiconductor and an n-type semiconductor are connected,
making a pn junction. P-type is a semiconductor containing holes (positively
charged ions). The n-type has a surplus of electrons.For a solar panel, light
breaks the chemical bonds of silicon which become the holes drifting towards
n-type for which a corresponding electron is paired and flow from n-type to
p-type (Sproul
A.,n.d.).
|
Figure
1 |
Figure
2 |
|
Figure
3 |
Figure
4 |
- P type semiconductor (left side) and an n-type
semiconductor (right side) is connected
- The junction causes a depletion layer where electrons of
the n-type and holes of the p-type combine
- An internal electric field forms at the junction
(diffusion)
- When light hits the cell, a drift current forms and a
hole is generated in the p-type semiconductor while in the n-type
semiconductor, electrons are generated. This is used in a circuit.
The solar cell type used for this experiment is
polycrystalline. It has a low temperature coefficientof resistance and better
suits an investigation of how temperature affects power output. Silicon has a
temperature coefficient that is negative, so resistance generally decreases with increasing temperature (Sproul A.,n.d.).
Figure
5 Differences Are Becoming Less Apparent
Aim
To
investigate the effect of lower temperature conditions on the overall
efficiency of the solar cell compared to higher temperatures. In other words, how
is the efficiency of a solar panel altered by temperature?
Outline
of Procedure
Apparatus
·
Beam lights
·
Solar panel
·
Insulated leads
·
Alligator clips
·
Laptop
·
Temperature measuring device
·
Light sensor
·
Voltage sensor
·
Current sensor
·
Data logger interface (Vernier Labquest Mini)-a 12-bit interface
·
Resistor
The size of
the polycrystalline solar panel used in this experiment was two sets of 10 cm by 2.5 cm cells on a
module board of total size 12 cm by 6.2 cm.The cell area is 50 cm2 in total. This may be used in the
calculations of efficiency.
No
short-circuit current or open-circuit voltage (approx. 0.6V) when power output
is zero was measured for reference. It was pre-determined that 100 Ohm
resistors allowed the greatest power to be generated.A
low
resistance will raise the current and lower the voltage. Conversely, a high
resistance will raise the voltage but lower the current. An optimal resistance
was found for the solar cell to reach its maximum power point. This resulted in
low current values nearing the lower extent of what the current sensor can measure
accurately. By contrast, the voltage sensor had an accuracy of 3.1mV at 12 bits
which allows accurate measurements. However, the current sensor had a range of
-0.6A to 0.6A. The current values read were 0.8 and3.5 mA on average, which was
only a small degree of 0.31mAunits out of a total of 4,096 units from -0.6 to
0.6A.
The current
increases slightly with an increase in temperature while the voltage decreases
greatly. This depends on the bandgap of the semiconductor and is the reason why
high temperatures lead to less power output. The energy of the light unable to
be changed into electricity becomes heat which raises the internal temperature
of the panel itself. When the temperature increases, the current increases a
little, however, the decrease in voltage is greater than that, which leads to
less power and thus lower efficiency.
Procedure Description:
1.Attach solar
panel to the stand on a piece of acrylic with blu-tack
2.Set three
torchesperpendicularly at around 15 cm from the solar panel ensuring the lights
are all facing the panel from the same distance
3.Connect
output connectors of solar panel to ammeter/voltmeter by attaching leads to the
circuit via alligator clips
4. Set a
light sensor in the middle of the solar panel and record for 60 secondsto
determine the amount of power of the light produced by the torches.
5. Measure the
distance from light to panel
6. Replace light
sensor with temperature sensor and then record the measurements of voltage and
current at ten records per minute for more than an hour
7. Repeat at
lower or higher temperatures with the incubator and the fridge. The thermostat
is set to a high temperature for the incubator to heat up. The fridge is turned
off before use, and once thawed, it is turned on and the experiment begins at
room temperature down to 3 degrees Celsius.
Diagram: Circuit Diagram and Connection Setup Drawing
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