Explain the working of a solar cell and draw its I-V characteristics .

Explanation

Solar cell is a p-n junction device which converts solar energy into electric energy.
It consists of a silicon ( or ) gallium - arsenic p-n junction diode packed in a can with glass window on top. The upper layer is of p-type semiconductor. It is very thin so that the incident light photons may easily reach the p-n junction.
Working `:` When light`( E= hv)` falls at the junction, electrons- hole pairs are generated near the junction. The electron and holes produced move in opposite directions due to junction field. They will be collected at the two sides of the junction giving rise to a photo voltage between top and bottom metal electrodes. Top metal acts as positive electrode and bottom metal acts as a negative electrode. When an external load is connected across metal electrods a photo current flows.
I-V characteristics `:` I-V characteristics of solar cell is drawn in the fourth quadrant of the co-ordinate axes. Because it dows not draw current.
Uses `:` They are used in calculators, wrists watches, artifical statellites etc.