One of the consistent problems with solar power plants has been the inefficient conversion of sunlight to electricity. Solar power plants are now concentrating solar power for better efficiency.

Solar Power Plants

Many power plants today use fossil fuels as a heat source to boil water. The steam from the boiling water rotates a large turbine, which activates a generator that produces electricity. However, a new generation of solar power plants uses the sun as a heat source. There are three main types of concentrating solar power plant systems: parabolic-trough, dish-engine, and power tower.

Parabolic-trough systems concentrate the sun's energy through long rectangular, curved U-shaped mirrors. The mirrors are tilted toward the sun, focusing sunlight on a pipe that runs down the center of the trough. This heats the oil flowing through the pipe. The hot oil then is used to boil water in a conventional steam generator to produce electricity.

A dish-engine system uses a mirrored dish similar to a very large satellite dish. The dish-shaped surface collects and concentrates the sun's heat onto a receiver, which absorbs the heat and transfers it to fluid within the engine. The heat causes the fluid to expand against a piston or turbine to produce mechanical power. The mechanical power is then used to run a generator or alternator to produce electricity.

A power tower system uses a large field of mirrors to concentrate sunlight onto the top of a tower, where a receiver sits. This heats molten salt flowing through the receiver. Then, the salt's heat is used to generate electricity through a conventional steam generator. Molten salt retains heat efficiently, so it can be stored for days before being converted into electricity. That means electricity can be produced on cloudy days or even several hours after sunset.


Solar power plants used to be a bit of mockery when they first came to be. By learning to concentrate power, solar power plants are getting the last laugh.