How practical is solar power for various devices? Assume that on asunny day, sun

Question

How practical is solar power for various devices? Assume that on asunny day, sunlight has an intensity of 1000 W/m2 at thesurface of Earth and that, when illuminated by that sunlight, asolar panel can convert 10% of the sunlight's energy into electricpower. For each device given below, calculate the area A of solarpanel needed to power it. (a) A calculator consumes 50 mW. FindA in cm2. Is A small enough so thatthe solar panel can be mounted directly on the calculator that itis powering? (b) A hair dryer consumes 1500 W. find A inm2. Assuming no other electronic devices are operatingwithin a house at the same time, is A small enough so thatthe hair dyer can be powered by a solar panel mounted on thehouse's roof? (c) a car requires 20 hp for highway driving atconstant velocity (this car would perform poorly in situationsrequiring acceleration). Find A in m2. IsA small enough so that this solar panel can be mounteddirectly on the car and power it in "real time"?

Explanation / Answer

In all cases, intensity = 100W/m2   =    0.01W/cm2    and     A = power / intensity, so . (a)   A = 0.050 / 0.01 = 5cm2       yes, it is smallenough . (b) A = 1500 /100 =   15m2       yes, it is smallenough . (c)    20 hp = 14920 Watts A = 14920 / 100 =   149.2m2       no, it is notsmall enough . . (c)    20 hp = 14920 Watts A = 14920 / 100 =   149.2m2       no, it is notsmall enough .

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