Question

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.

Answer 1

Power used by the family, $P=8kW=8\times {10}^{3}W$
Solar energy received per square metre = 200 W
Efficiency of conversion from solar to electrical energy = 20%
Area required to generate the desired electricity = A
As per the information given in the question, we have:
$8\times {10}^3=20\%\times (A\times 200)=\frac{20}{100}\times A\times 200\therefore A=\frac{8\times {10}^3}{40}=200m^2$
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 $14m\times 14m$.