The light energy that falls on a square meter of ground over the course of a typ
ID: 1530435 • Letter: T
Question
The light energy that falls on a square meter of ground over the course of a typical sunny day is about 20 MJ. The average rate of electric energy consumption in one house is 1.0 kW.
A) On average, how much energy does one house use during each 24 h day? Express your answer using two significant figures.
B) If light energy to electric energy conversion using solar cells is 16 % efficient, how many square miles of land must be covered with solar cells to supply the electrical energy for 350000 houses? Assume there is no cloud cover. Express your answer using two significant figures.
Explanation / Answer
a)
energy used by one house in one day is
E=Pt=(1*103)*(24*3600)
E=8.64*107 J=86 MJ
b)
energy produced by solar cells in one day per square meter
Esolar/A=0.16*20=3.2 MJ/m2
total Energy needed for 350000 houses
Etotal=350000*86.4=3.01*107 MJ
Area needed for solar cells
A=3.01*107 /3.2=9.406*106 m2 or 3.6 miles
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