SOLAR TODAY Blog

Want a quick, rough estimate of how much solar power you could generate on your roof or in your yard?

Roofray.com is a cool mashup of Google Earth with a solar power analyzer. Enter an address and you get a satellite view of the property. You can then select a portion of the roof or yard to take a solar array, outlining the system by clicking on its corners. And you can specify the array’s angle to horizontal. Using climate data for your latitude and longitude, the website then quickly calculates the square footage of the array and its maximum theoretical power capacity. It told me, for instance, that my garage roof could support enough PV to max out the local utility-company rebate.

One nice feature here is that most Google Earth satellite photos are taken near mid-day, so as to minimize tree-shading on rooftops. This means you can draw your array in the sunniest part of the lot, or see what trees might have to be pruned in order to maximize sun on the roof.

The system won’t design your solar system for you, but it will give you some ballpark figures to play with, and let you know whether it makes sense to take the next step.