Before plopping panels on your roof, consider other ways to conserve electricity, like switching to CFL or LED lightbulbs and replacing inefficient electrical appliances like old refrigerators. “Conservation is the leanest means to reducing electrical use and fossil-fuel consumption,” Moore says. “PV panels require a lot of energy to produce, ship, install, and dispose of.”  Photo 3 of 8 in Denver's Energy Efficient  Home