Reply #31: At current rates of efficiency for the most common type of PV cells

[Brian Sweat]

It would take less area to produce all of this nations energy needs than are currently covered by roads in this country. Common PV cells are about 13% efficient.

In the desert of the south west, there is an average of about 7.5 kilowatt hours of energy available per day per square meter. At 13%, that means that mean that about 975 watt hours can be collected per quare meter or 975 MW hours per square kilometer. In the U.S. we use about 9.531 GW hours of electricity per day. That means that is would take less than 10,000 square kilometers to produce all of the electricy that we need.

We would also need energy for transportation, but we use less energy for transportation than we do for electricity. So we could produce all of our energy needs with less than 20,000 square kilometers or 10,000 square miles.