Question

A family uses 8kW of power. (a) Direct solar energy is incident on the horizontal surface at an average rate of 200 W per square metre. If `20%` of this energy can be converted to useful electrical energy, how large an area is needed to supply 8kW? (a) Compare this area to that of the roof of a typical house.

Answer 1

a) Power used by family, p=8 KW = 8000 W As only 20% of solar energy can be converted to useful electrical energy, hence power 8000 W to be supplied by solar energy = 8000W//20 = 40000 W
As solar energy is incident at a rest of 200 `Wm^(-2)`, Hence the area needed A= 4000 W/200 `Wm^(-2)=200 m^(2)`
b) The area needed is comparable to roof area of a large sized house.