Workers install a solar panel system on the roof of a home in Gainesville, Fla.

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Where your home is situated has a big effect on your solar-power efficiency. It's an obvious concern: If your electrical-power generation depends on sunlight, things like towering shade trees and tall, shadow-casting buildings are going to be a problem.

It's an even bigger problem than some people realize, though. Different types of panels react differently to shade. While a poly-crystalline panel will substantially reduce its output if any part of the panel is shaded, a mono-crystalline panel will stop producing electricity entirely.

So to build a solar-powered home, it's necessary to make sure there are no shadows on the roof's panel area during the sunniest hours of the day (typically from 10 a.m. to 2 p.m.), and preferably during all sunny hours [source: AEG]. The more hours the panels spend exposed to full sun, the more efficient the power generation will be.

Achieving the greatest efficiency level might mean cutting back trees on your property (and keeping them cut back). If your home is surrounded by tall buildings that block the sun from your roof, this is a much bigger problem.

Which brings us to the next big consideration: sunlight.