Energy from the sun - Multiple forms of energy originate with the sun. This energy is the sustaining force that allows humans to live on Earth. Production of this energy first begins in the sun's core. The sun, like most stars, is mainly made of hydrogen. Its core is so hot and compressed that large amounts of hydrogen atoms stick together. These atoms turn into helium, in a process called atomic or nuclear fusion. This transformation produces massive amounts of energy. The energy manufactured in the center of the sun then radiates outward from the core. The sun's glow and heat result from this process.

The energy that results from nuclear fusion on the sun produces most of the energy on Earth. Once harnessed on Earth, solar energy can be used for electricity and heat. Electricity is either converted by solar cells (called photovoltaic) or through solar power plants. Solar cells are commonly used on rooftops to help provide power and for such items as calculators. Solar power plants convert energy to steam in order to power generators that in turn provide energy to homes and businesses. Heat from the sun is also a useful energy source. The thermal energy is collected with solar cells and later converted to heat as needed.

Photovoltaics (PV) is a method of generating electrical power by converting solar radiation into direct current electricity using semiconductors that exhibit the photovoltaic effect. Photovoltaic power generation employs solar panels composed of a number of cells containing a photovoltaic material. Materials presently used for photovoltaic’s include monocrystalline silicon, polycrystalline silicon, amorphous silicon, cadmium telluride, and copper indium selenide/sulfide. Due to the growing demand for renewable energy sources, the manufacturing of solar cells and photovoltaic arrays has advanced considerably in recent years.

As of 2010, solar photovoltaic’s generates electricity in more than 100 countries and, while yet comprising a tiny fraction of the 4.8 TW total global power-generating capacity from all sources, is the fastest growing power-generation technology in the world. Between 2004 and 2009, grid-connected PV capacity increased at an annual average rate of 60 percent, to some 21 GW. Such installations may be ground-mounted (and sometimes integrated with farming and grazing) or built into the roof or walls of a building, known as Building Integrated Photovoltaic’s or BIPV for short, while BAPV is Building Applied PV -– it’s a retrofit added to the building long after construction. Off-grid PV accounts for an additional 3–4 GW.

Here’s an interesting article you may want to take a look at.

http://www.cnn.com/2010/TECH/innovation/08/09/smart.grid/index.html