Solar energy is free, but it is diffuse. Here are some relative economics

On a clear day at noon on the earth's surface the sunlight puts out about 1000 Watts/m² If you collected this energy for 1 hour, you'd have about 1 kilowatt-hour of energy. A kilowatt-hour costs around 10 cents from the power company. In a sunny climate you'd get the equivalent of about 2000 hours of this or 2000 kwh of electricity. This would be the equivalent of $200 of electricity.

But unfortunately you can never harness all this energy and only get a percentage. If you assume you can get 10% efficiency, this means that you could get about $20 for every m² per year or about $2 for every square-foot per year. That's not really very much when you think about it.

A square meter of solar panels might cost around $500 or more so this means that it would take at least 25 years to pay for the panel.

Now assume that you could get 5x the electricity from that same panel. That means that you'd get $100 of electricity/year and it would only take 5 years to pay for the panel. Yay! That's a big improvement, but unfortunately now you have to add the price of the concentrator.

$500 Solar Panel at 5x concentration with $100 of yearly revenue

Cost per m² of 5x concentrator Additional Cost Total Cost Time to Payback
$200/m² $1000 $1500 15 years
$100/m² $500 $1000 10 years
$80/m² $400 $900 9 years
$60/m² $300 $800 8 years
$40/m² $200 $700 7 years
$20/m² $100 $600 6 years
$10/m² $50 $550 5.5years

These are only ball park numbers, but it shows that moderate concentration ratio's with low cost concentrators can dramatically change the time to payback for solar panels. But $20/m² is about the price of carpeting. Can a tracking solar concentrator with gears and motors and control systems be built for that price?

next: The technology