Thursday, 26 November 2009

Stirling Dish - Off Grid Independence

Stirling-Dish Systems are small power generation sets which generate electricity by using direct solar radiation. The capacity of a single unit is typically between 5 and 25 (50) kWel. This size and the modularity of the single units qualifies the Stirling-Dish system for very flexible applications. They are ideal for stand-alone or other decentralised applications. In clusters with a capacity of up to 10 MW, Stirling-Dish systems can even meet moderate-scale grid-connected demands.

Stirling-Dish Systems transfer concentrated solar radiation with high efficiencies [up to nearly 30%] into electrical energy. Essentially the system consists of the following components:

  • · Parabolic solar concentrator
  • · Tracking system
  • · Solar heat exchanger (Receiver)
  • · Stirling engine with generator
The parabolic concentrator reflects the incoming solar radiation onto a cavity receiver which is located at the concentrator’s focal point. The solar radiation is absorbed by the heat exchanger (receiver) and thus heats the working gas (helium or hydrogen) of the Stirling engine to temperatures of about 650oC. This heat is converted into mechanical energy by the Stirling engine. 

An electrical generator, directly connected to the crankshaft of the engine, converts the mechanical energy into electricity (AC). To constantly keep the reflected radiation at the focal point during the day, a sun-tracking system rotates the solar concentrator continuously about two axes to follow the daily path of the sun.
 
The electrical output of the system is proportional to the size of the reflector, its optical performance and the efficiencies of the Stirling engine and the generator.

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