The sun deliverse 103 W/m2 of electromagnetic flux to the earth's surface. The total power that is incident on a roof of dimensions 8m × 20m, the solar energy incident on the roof in 1 hour will be:

5.76 × 108 J 5.76 × 107 J 5.76 × 106 J 5.76 × 105 J

5.76 × 108 J

E = power × time = 1.6 × 105 × 3600 = 5.76 × 108 J