The correct answers are:
**South Texas: 305 W/m ^{2}
northern U.S.: 256 W/m^{2}
northern U.S. (winter): 115 W/m^{2}**

These the results are, respectively: 959 W/m^{2} / pi; 805 W/m^{2} / pi; and (451 W/m^{2} / pi) * 0.8.

These results would be the average available energy only if there were a method to convert 100% of this flux to useful power. In reality, perfect efficiency in converting solar energy to useful power is unattainable. The best efficiency of commercially-available solar photovoltaic collectors (i.e. collectors that are cheap enough to be cost effective) is 16%. The best efficiency for any laboratory solar cells is 30%.

**Question 5.**

Using the more optimistic value of 30%, find the average power that can be harnessed for each location from above.

How do your answers compare to the 1,368 W/m2 you started with?

What additional factor have we ignored?

Click **here** to check your answers and continue...

© 2001-2002, 2005 by Wm. Robert Johnston.

Last modified 11 January 2005.

Return to Home. Return to Environmental Topics. Return to Solar power worksheet introduction.