PHYX/GEO-3150 Homework 4

1. The new college of agricultural building on campus uses solar cells (PV) on its south side to
generate electricity.
a) Walk along the south side of the building and estimate the total area of the solar
cells. Give the value in m2.
b) Assume that the solar insolation in Logan is 200 W/m2 and that the efficiency of the
solar PV cells is 15%. Calculate the average energy (in kWh) that these solar cells
generate per day.
c) A typical Utah home uses about 25 kWh of electricity per day. Approximately, how
many homes can be powered by the electricity generated by the solar cells on the
agricultural building?
PHYX/GEO-3150 Homework 4 Due: 7 March, 2013
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2. Assume that the people of Utah have decided to become energy independent day and that
their plan is to use solar photo-voltaic (PV) energy for all their energy use (maybe not too
realistic, but let’s assume it anyways). Also assume that the average Utah citizen uses 250
kWh of energy every, that the solar insolation in Utah is about 200 W/m2 and that the
efficiency of the solar cells is 15%.
a) Calculate the area of the solar PV system that is needed to fulfill this dream. Give
b) Place the area calculated in a) on a map of Utah.
PHYX/GEO-3150 Homework 4 Due: 7 March, 2013
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3. The newspaper article shown on the next page appeared last Saturday in the Herald Journal.
a) Briefly describe the problem addressed in the article and the solution that the author
proposes.
b) Calculate the area of the solar power plant that is needed to replace the 2,250-
megawatt coal-fired power plant. Assume that the solar insolation on the Navajo
land is about 225 W/m2 and that the solar panels have an efficiency of 15%. (1
megawatt is 1Million Watts)
PHYX/GEO-3150 Homework 4 Due: 7 March, 2013
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PHYX/GEO-3150 Homework 4 Due: 7 March, 2013