SOLAR POWER GENERATION TECHNOLOGIES
As already outlined, there are two ways of turning the energy contained in sun- light into electricity. The first, called solar thermal power generation, involves using the sun simply as a source of heat. This heat is captured, concentrated, and used to drive a heat engine. The heat engine may be a conventional steam turbine, in which case the heat will be used to generate steam, but it could also be a closed-cycle turbine system using an organic thermodynamic fluid, a gas turbine, or a Sterling engine.
The second way of capturing solar energy and converting it into electricity involves use of the photovoltaic or solar cell. The solar cell is a solid-state device like a transistor or microchip. It uses the physical characteristics of a semiconductor such as silicon to turn the sunlight directly into electricity. The simplicity and durability of the solar cell makes it an extremely attractive method of generating electrical power.
As with several other renewable technologies, solar energy is intermittent; it is only available during hours of daylight. In many parts of the world where there is a good solar resource, high levels of sunlight often coincide with a peak in demand for air conditioning, so solar power, particularly in the form of rooftop solar panels, can provide synchronized peak power. In addition, some solar thermal power plants can incorporate thermal energy storage, which will allow them to operate round-the-clock, depending on the size of the energy store. Otherwise, solar power is generated when the sun shines and must be fed into the grid immediately. This means that under normal circumstances, the solar power must be dispatched when it is available, while other generating plants must be ready to provide an alternative source of power when solar power is not available.