Some people don't mind outfitting their roofs with solar cells. Solar cells contain photovoltaic materials, which convert sunlight directly into electricity. That electricity can then be used to heat, cool and light a house. Solar cells have been around for decades. They power everything from space ships to calculators. There's one problem, however. Today's cells are not efficient. They covert only about 10 percent of sunlight into energy [source: Herberman].
Moreover, such photovoltaic systems are expensive. Depending on the size, it costs between $27,000 and $36,000 to install a photovoltaic system with solar panels. It would take about 12 to 15 years to recoup all that money on your energy bills. However there are tax rebates and other incentives that can reduce the economic impact of installing an active solar energy system [source: Scherzer].
There are cheaper active solar heating systems on the market, though. Such systems use liquids, including water, or air. In both of these systems, the liquid or air is able to absorb the sun's energy through a collector. Those collectors then transfer the sun's heat directly to the home or into a storage system. From there the heat is dispersed through the house [source: U.S. Department of Energy].