Solar Dish Systems: Concentrated Solar Radiation

Solar dish systems are also known as distributed-point-focus systems. Solar dish systems feature small, parabolic mirrors that are dish shaped which reflect sunshine onto a receiver. A two-axis tracking system moves the mirrors to capture the maximum amount of solar energy available to it. The receiver is usually mounted above the mirrors at the center of the dish, its focal point. Inside the receiver is a fluid, which transfers the intense heat created by focusing the sunlight on the receiver. The dishes can be used singly or linked together.

Solar dish systems may be part of a dish-engine system. This solar dish engine is an electric generator that "burns" sunlight instead of gas or coal to produce electricity. The dish, a concentrator, is the primary solar component of the system, collecting the energy coming directly from the sun and concentrating it on a small area. A thermal receiver absorbs the concentrated beam of solar energy, converts it to heat, and transfers the heat to the engine/generator. The Sterling engine converts the energy into mechanical power. This happens by the compression of the working fluid, like steam, with the heat. It is then expanded via a turbine or piston. After mechanical power is produced, an electric generator or alternator turns the mechanical power into electrical power.

A dish-engine system can also be linked. If they are linked, they can potentially produce a significant amount of electricity. Ten 25-kilowatt dish-engine systems can produce 250 kilowatts of power. This would only require an acre of land.

Dish-engine systems can also be hybrids. That is, they might be combined with natural gas into a hybrid that can ensure the constant production of electricity.

Opportunities are emerging for the deployment of solar dish-engine systems in the Southwest U.S. Many states are adopting green power requirements in the form of "portfolio standards" and renewable energy mandates. While the potential markets in the U.S. are large, the size of developing worldwide markets is immense. Solar dish-engine systems are being developed for use in emerging global markets for distributed generation, green power, remote power, and grid-connected applications. Individual units, ranging in size from 9 to 25 kilowatts, can operate independent of power grids in remote sunny locations to pump water or to provide electricity for people living in remote areas. Largely because of their high efficiency and "conventional" construction, the cost of dish-engine systems is expected to compete in distributed markets.

Dish Stirling engine of a solar dish system