Cost of Solar Photovoltaics for the U.S.
In astronomy we’re fond of making order-of-magnitude estimates. These are also called “quick and dirty” or “back of the envelope” calculations. By playing fast and loose with the details one can frequently come up with an answer that while not highly accurate, should be at least within a factor of 10 of the true answer (that is, within one order of magnitude). Following up on my estimate for the area of solar power cells needed to supply the entire country’s electricity needs, I thought it would interesting to estimate the cost of such a system.
I estimated 460 million kiloWatts as the continuous average electrical energy consumption for the country based on data from the Department of Energy website. (As a quick check on this estimate, that is about 1.5 kW, or 15 100-Watt bulbs lit 24/7 per American. That seems like a reasonable number.) A web search for companies that sell rooftop solar panels to homeowners gave me a price of $600 for a panel that supplies 100 Watts (0.1 kW). If we did our whole country with those panels at that price, it would take 4.6 billion of those panels, and at $600 apiece that comes to about $3 trillion. This particular order-of-magnitude estimate is almost certainly high because at the scale needed for utilities, bulk manufacturing would drive the price way down. But even with this high estimate, that is $10,000 per American, or 10 Iraq wars. That’s to supply all the country’s current electrical needs. Of course such a large system would take many years to put in place, and not all of the country’s power needs should be switched to solar. But these order of magnitude estimates show that it is feasible both technically and economically to be electrically self-sufficient.