Photovoltaic (PV) technologies transform radiation from the sun directly into a DC electric current. They work differently from thermal solar systems, which use the sun's heat instead of its light rays.
Solar shingles, made up of silicon-based photovoltaic cells. They are not attached to the roof but are the roof. A 30 to 40 square metre block of shingles can provide 60 to 90 percent of the annual power needs of a typical three-bedroom home, depending on how much sun it gets. Glass-laminated solar shingles can last twice as long as traditional roofing, and can be installed by local contractors. However, in 1999 this technology cost about about twice as much as conventional electricity.