A family uses 8 kW of power. (a) Direct solar energy is incident on the horizontal surface at an average rate of 200 W per square meter. If 20% of this energy can be converted to useful electrical energy, how large an area is needed to supply 8 kW? (b) Compare this area to that of the roof of a typical house.
(a) Usable power per square meter=8×103W Solar energy received per square meter =200W/m2 The efficiency of conversion from solar to electricity energy = 20% Area required to generate the desired electricity is A. As per the information given in the question, we have 8×103=10020A×200 A=200m2 (b) The area of a solar plate required to generate 8 kW of electricity is almost equivalent to the area of the roof of a building having dimensions 14 m x 14 m. (close to 200 sq m).
