The sun is the Earth's most abundant and primary source of energy, light and heat. It powers and shapes our ecosystems, natural cycles and seasons. In short, it sustains the world around us. Even the way the sun’s energy interacts with the Earth’s atmosphere determines our weather patterns, rainfall, plant, and vegetation growth. Solar energy is at the root of most forms of energy that humans use for power. Scientific American magazine states, “The energy in sunlight striking the earth for 40 minutes is equivalent to global energy consumption for one year. Solar energy’s potential is off the charts.” The sun’s energy, known as solar radiation, can be converted through technology, into forms of power, such as solar-thermal (or heat) and electricity.
In recent era it became use full again with a genius idea. If input energy, to heat up engine, comes for free efficiency doesn’t matter. If solar energy concentrated at a point and supplied to stirling engine coupled with and alternator can produce free electricity. Biggest issue for this kind of systems is keeping focus on engine.
Placed at the focus of a parabolic mirror a Stirling engine can convert solar energy to electricity with efficiency better than non-concentrated photovoltaic cells, and comparable to Concentrated Photo Voltaics. On August 11, 2005, Southern California Edison announced an agreement with Stirling Energy Systems to purchase electricity created using over 30,000 Solar Powered Stirling Engines over a twenty year period sufficient to generate 850 MW of electricity. These systems, on an 8,000 acre (19 km2) solar farm will use mirrors to direct and concentrate sunlight onto the engines which will in turn drive generators.
