What is a solar cell ? How does it work ? Write its one use.

Explanation

Solar cell: A special p-n junction which converts solar energy into electrical energy is known as a solar cell or photovoltaic cell. Junction surface of these cells is kept large so that large radiations are causht. A simple solar cell consists of a p-n junction diode of which n-region is very thin and p-region is thick. Nickel plated contacts are connected through a load resistance `R_(L)`. Working: When solar radiations fall on the solar cells, electron hole pairs are generated in n-region and p-region of junction in diode. The electrons from the p-region diffuse through the junction to n-region and holes from p-side diffuse to n-region through the same junction due to electric field of depletion layer. If the p-n junction diode is open circuited then electrons and holes will collect on the two sides of the junction. This gives rise to an open circuit voltage `V_(sigma)`. When an external resistance is connected across the junction diode, electric current flows through the circuit. This electric current is directly proportional to the intensity of sunlight.

Uses of Solar cells:
(i) These are used in solar water heaters.
(ii) These are used to produce electricity in artificial satellites.
(iii) These are used in calculators.
(iv) These are used in street lights.