At noon on a nice summer in boulder, each 1 cm2 of surface is expressed to perha
ID: 2101184 • Letter: A
Question
At noon on a nice summer in boulder, each 1 cm2 of surface is expressed to perhaps 200 mW (milliWatts)of visible radiation. You are considering adding solar panels to your house and want to see whether they will provide enough energy for your household needs. If your solar panel covered an area of 3 meter by 6 meters(that's about a dozen typical solar panels) How much solar power would be hitting the surface of the panel at noon on a clear day? (And, does 3 m* 6 m seem like a reasonable size, by which we mean, would it fit on a typical household roof?) If the solar panels were 15% efficient at converting the solar energy to the electrical energy, how much electric energy would have been harnessed in 1 hour? (Assume hat the exposure is pretty steady for that hour at 200mW/cm2). For how many hours could this amount of energy power a 100 W bulb? The above problems considered peak solar intensity at noon on a nice summer day. Of course, that doesn't last all day, nor all year. Make some reasonable "guesstimates" to predict how much electrical energy these panels would likely produce over the course of a (Boulder) year. An average American home uses about 500-100kW hrs of electrical energy each month. Will these panels be sufficient for "average Americans"? Given your numbers,(and considering how Boulder sunshine compares to other US cities) What can you conclude about the role of the solar energy in the US' future energy balance?Explanation / Answer
a)Power=Intensity*Area=200*10^-3*3*6*10^4W=36000W
b)Electric energy in 1 hour=efficiency*Power*time=0.15*36000*3600J=1.944*10^7J
=5.4kWh
No . of hours=Total energy/energy consumed by bulb in 1 hour=5.4kWh/0.1kWh=54 hours
c)Since light is avaialble on 12 hours a day, we can assume an average power of 70mW/cm^2 through the year.
Total energy produced/year=70*10^-3*3*6*10^4*0.15*365*24*3600=5.96*10^10J=16556kWh
Energy required by homes/year=(500-1000)*12=6000-12000kWh.
Clearly this requirement can be covered.
Solar energy can play a very important role in the US future energy balance.
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