Suppose the Solar radiation is 850 W/m2 and you collect 20% of energy that falls on the reflecting surface of a hot dog cooker. If you need 240 watts for the cooker, what is the minimum collector area?

The minimum collector area is 1.412 m2 (rounded to 3 decimal places)

Explanation:

Stepwise procedure-

Total solar radiation falling / unit area = 850 W/m2

Given = Only 20% of the energy is collected

Need = 240 W

The Minimum surface area of collector=?

Let the minimum surface area be "x" m2

Total solar radiation falling = radiation / unit area * total area

= x*850 W/m2

Total solar radiation utilised = (20/100) * x*850 (given only 20% is utilised)

Since the need is 240 W

Hence the total solar radiation utilised = energy needed

Thus 240 = (x*850) / 5

x = (240*5) / 850

The minimum collector area is "x" = 1.412 m2