Energy from the sun's radiation can be captured and converted to electricity by a number of methods, including photovoltaic panels, solar thermal electric and solar thermal gas technology.

The most common form of large-scale solar generating technology is solar thermal as this technology has advanced to the point where it is capable of providing bulk power, similar to conventional, fossil-fuelled power stations.

Turning the sun's heat energy into electricity requires direct sunlight to be concentrated and collected by Concentrating Solar Power (CSP) technologies that turn the sun's energy into medium-to-high temperature heat. This heat is then used to create steam that drives a conventional steam turbine generator to produce electricity.

Because solar energy relies on daylight and clear, sunny weather for maximum efficiency, the production of solar power can be variable, and dependent on energy storage systems to overcome cloudy or night-time periods. Clouds, humidity, fumes or dust in the atmosphere can reduce the efficiency of solar thermal plants.

Potential energy storage technologies involve solar heat being collected during periods of peak sunlight and stored in liquid or solids such as graphite, molten salt, ceramics or concrete, to be released at night and allow electricity generation to continue.

Thermal energy storage can extend the operation time of solar thermal power plants so they can effectively run on solar energy 100 per cent of the time. Sometimes solar thermal generators are combined or integrated with other energy sources, such as gas, to boost electricity output when necessary.

For solar thermal to work it needs a concentrator, a receiver, transport or storage and power conversion. The three most common solar thermal concentrator technologies are the parabolic trough, the central receiver or solar tower, and the parabolic dish.

Parabolic trough

Trough-shaped mirror reflectors concentrate sunlight onto an absorber tube at the focus of the mirror that captures the sun's heat. The tube carries a heat-storing fluid, which then flows through heat exchangers that use the heat to create steam. The steam then drives a conventional steam turbine generator, or sometimes a combined steam and gas turbine.

Central receiver or solar tower

A large number of mirrors are arranged in a roughly circular field around a central tower and concentrate the sun's energy on a receiver at the top of the tower. Each mirror has a tracking system to enable it to turn as the sun moves across the sky, so that the reflected, focused light is always directed onto the receiver.

The heat transferred to the receiver can be used to generate steam. This steam can then be used in a conventional turbine, or in a combined steam/gas turbine.

In a SolarGas system, the heat at the receiver is used to drive a chemical reaction that stores solar energy in the chemical bonds of a gas.

Parabolic dish

A dish-shaped reflector is used to concentrate sunlight onto a central receiver, which heats a fluid or gas that is used to generate electricity in a mini-turbine attached to the receiver. Parabolic dishes also have tracking systems to follow the sun.