(a) Power used by family is given as $p=8 \mathrm{KW}=8000 \mathrm{~W}$
Solar energy received per square metre is given as $200 \mathrm{~W} / \mathrm{m}^{2}$
Percentage of energy converted to useful electrical energy is given as $20 \%$
As solar energy is incident at a rate of $200 \mathrm{Wm}^{-2}$, the area required to generate the desired energy will be $A$
Useful electrical energy produced per second can be calculated as,
$=(20 / 100) \mathrm{A} \times 200=8000$
$A=4000 \mathrm{~W} / 200 \mathrm{Wm}^{-2}=200 \mathrm{~m}^{2}$
(b) $14 \mathrm{~m} \times 14 \mathrm{~m}$ is the area needed is comparable to the roof of a large house of dimension.