We cannot make use of solar cells to meet all our energy needs since:

(a) Solar cells have very low efficiency. At present, the best designed solar cells can generate 240 Wm^-1 in bright sunlight with a maximum efficiency of 25%. So, they can convert 25 percent of the light falling on them into electricity.

(b) Solar cells are very expensive. The special grade silicon needed for making solar cells is expensive. The silver wires used to interconnect the solar cells is also very expensive. So, the extensive use of solar cells in generating power is limited due to their high cost.

(c) Solar cells can only be used during daylight. During night or during cloudy days, the solar cells are unable to produce electricity.