The energy flux arriving at Earth from the Sun is known as the solar constant and has a value of 1.37 × 10³ watts per square meter. Assuming that the atmosphere absorbs 50% of the energy and that a 5-m² roof collector is available to collect energy with a 30% efficiency, how much of this solar energy would then be available for use in the house for water or house heating, etc.? (1 KW = 1 kilowatt = 1000 W)

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Quizplus · Accepted Answer

The solar constant is 1.37 × 10^3 W/m^2. With 50% absorbed by the atmosphere, 50% reaches the surface, so 0.5 × 1.37 × 10^3 = 685 W/m^2. For a 5 m^2 collector at 30% efficiency: 685 W/m^2 × 5 m^2 × 0.3 = 1027.5 W, which is about 1 KW.

The Energy Flux Arriving at Earth from the Sun Is