Solar cells warm up when they are placed in sunlight. Consider a module with are

Question

Solar cells warm up when they are placed in sunlight. Consider a module with area 0.5 m2 and a mass of 1.25 kg. When you set the cell out in “standard” sunlight (1 kW/m2) , and it isn’t hooked up electrically, you notice that its temperature rises from 20 C to 30 C after the first minute of exposure. The next time you set the cell out, you remember to hook it up; you notice that the temperature increases to 28 C in the first minute.

a. Show calculations for the electrical power that the cell is providing when it is hooked up and for the cell’s conversion efficiency.

b. Show a calculation for the specific heat of the module, and compare it to the specific heat of water.

Explanation / Answer

a) we know that I = power / Area ==> P = I * A = 1 x 10^3 * 0.5 = 500 W b) Q = m c dT ==> Pt = m c dT ==> c = P t / m dT = 500 * 60s / 1.25 * 10K = 2400 J/ kg and Q = m c dT ==> Pt = m c dT ==> c = P t / m dT = 500 * 60s / 1.25 * 8K = 3000 J/ kg

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