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DiscoverCircuits.com
-- Hobby Corner
Last Updated on:
03/19/2008 06:54:11 AM |
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Solar Cell Test Fixture |
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If you are considering building your own solar panel, you might try building the solar cell
tester shown below. When constructing a solar panel it is important to make sure that all the solar cells used in the panel be closely matched
for their short circuit current. One weak cell will lower the efficiency of the whole panel. The system shown allows individual solar cells to
be tested for their short circuit current under a constant light intensity condition. The system uses a low voltage 25 - 50 watt halogen spot
light to simulate the light from the sun. A small PIN photodiode is placed in the path of the light from the lamp and is connected to a
circuit, which converts the light intensity collected by the diode into a voltage. Another circuit compares that voltage to a reference. The
error signal is fed to a pulse width modulation circuit, which controls the amount of power fed to the lamp. The result is a uniform light
source, whose intensity remains fixed. The system can be calibrated to produce a light intensity equal to one sun. |
| The assembly could be made from piece of plywood with cutout for the test area.
A bracket of some kind could hold the lamp assembly below the window. I’d recommend a piece of high temperature frosted glass as a light
diffuser to insure a more uniform light pattern. I think a glass window area about 6 inches by 6 inches would be big enough for most solar
cells. The current generated by the solar cell under test is measured by any digital multimeter, which can measure a few amps of current. |
| I will add the complete control circuit for this system later. Click on Drawing to view PDF |
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