Current-Voltage Characteristics of a Silicon Solar Cell

Solar cells are the source of fascination to students. It is profitable to introduce the fundamentals of photovoltaic devices to students at an early stage of their undergraduate program. Here, we make a simple experiment where students learn to plot the I-V characteristics of a solar cell and measure important photovoltaic parameters such as the fill factor and light conversion efficiency. To complete the experiment a commercial polycrystalline silicon solar cell with an active area of ~100 mm x 80 mm was illuminated from a non-standard light source with an intensity of ~50 mW/cm². To measure photovoltage and photocurrent, a circuit was completed using a voltmeter, an ammeter, and potentiometer. Short circuit current (I_SC) was first measured keeping the resistance in potentiometer minimum; current was then slowly decreased to a minimum by increasing the resistance, at which the measurement of open circuit voltage (V_OC) was taken. Incandescent light bulbs of power 150 W, 60 W and 14 W were used to illuminate the device. The I-V measurement of the device confirmed open circuit voltage of 20.805 volts, short circuit current of 22.3 mA and fill factor of 74%. Maximum photo-conversion efficiency of 8.5% was recorded when the device was illuminated with 150 W power source.  The I-V characteristics were also completed by varying the distance of the solar cell from the light source, by changing the angle of incidence, and by illuminating the solar cell with light of particular colors using translucent material color filters. Output powers of the device in each measurement condition were also calculated. Finally, dark J-V characteristics were also demonstrated to understand the diode behavior of the solar cells.