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(a) A solar collector is 12.0% efficient in gathering solar energy and convertin

ID: 1473138 • Letter: #

Question

(a) A solar collector is 12.0% efficient in gathering solar energy and converting it to heat. If the average intensity of sunlight on one day is 700 W/m2, what area should your collector have to gather energy at the rate of 140 W?
1.667 m2


(b) What is the maximum cost of the solar panel if it must pay for itself in two years of operation averaging 9.00 hours per day? Assume that it earns money at the rate of 2.00¢ per kilowatt-hour. There are 365.25 days in a year.

$

I got the answer for part a, only need help with part b.

Explanation / Answer

Money earned in 2 years must be total cost of solar panel

t = 2 year
= 2*365.25 days
= 2*365.25 *9 hr
= 2*365.25 *9* 3600 s
=2.367*10^7 s

Energy produced in this time t,
E = P*t
= 140 W* 2.367*10^7 s
= 3.314*10^8 W-s
= 3.314*10^5 KW-s
= 3.314*10^5/3600 KW-hr
= 92.06 KW-hr

Cost = 2.00¢ per kilowatt-hour * 92.06 KW-hr
= 184.12 ¢

Answer: 184.12 ¢