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Unformatted text preview: Indiana U, Physics Dept (H.O. Meyer 7/06) 24- 1 Lab #24: Photo-Voltaic Converters Goal: Study the performance parameters of an amorphous silicon photo-voltaic converter. Determine the power output as a function of the load resistance, the irradiance, the angle of incidence, and the temperature. Equipment: Solarex, SA-1, amorphous silicon converter module, Hubbard insolation meter, digital multimeter. 1 Physics: 1.1 Photodiodes Electronically, the converter behaves like a photodiode. The current I through a photodiode and the voltage U across it are related by the so-called Shockley equation ( ) g U d I e I I + − = ⋅ 1 α , (1) where the dark current I d and the constant α in the exponent are parameters that depend on the temperature and on the type of diode, and I g is the photo- generated current (i.e., I g =0 without illumination). Note, that the photo-current is in the reverse direction, i.e., I g is a negative number. The voltage across the diode when no current is flowing is called open-circuit voltage U oc , and the current that flows when the diode is shorted is called short-circuit current, I sc . A typical diode characteristic ( I versus U ) is shown in fig.1. ) is shown in fig....
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- Spring '11