This article gives an overview of different types of solar power plants which can be used to generate power from solar energy.
- 1 Definition of solar power plant
- 2 Types of solar power plant (s)
Solar electrical power plants require large collection field covering several km2 area, complex and costly sun-tracking system for large heliostats, long piping system and large thermal storage system.
Definition of solar power plant
Such system which uses the photovoltaic to convert sunlight energy to electrical power and transfer it to utility or user is called solar power plant.
There are two main types of solar power plant
Types of solar power plant (s)
- Solar distributed collector power plants
- Solar central receiver power plants
- Solar pond power plant.
Distributed solar power plant collector:
In distributed receiver solar power plants, parabolic trough collectors with line focus are most commonly used. The sun rays are reflected by parabolic or cylindrical troughs. The reflected rays are focused on linear conduit (pipe) located along the axis of the trough.
Figure 1 shows a schematic diagram of a distributed collector solar thermal power plant. The major components are the following:
- Trough collectors distributed in the solar field
- Piping system for primary heat transport loop
- Heat transport fluid pump
- Boiler cum steam generator
- Secondary (working) fluid loop (steam)
- Steam turbine
- Hot condensate pump – Water loop
- Feed water heater- Steam loop
- Boiler feed pump
Solar distributed collector power plants
Central receiver solar power plant (s):
In this type of solar power plant, a central receiving scheme is used. Such type of solar thermal power plant lies in the range of 50-200 MW (Figure 2). The high capacity is possible due to high temperature steam in the central receiver results in high efficiency of plants. In such solar power plant, several heliostats are located on the ground level. The heliostat reflects sun rays towards a central receiver mounted on a tall tower (Figure 3). The large central receiver power plant is usually built with modular concept. Each power plant may have 2 to 10 modules. Each module may be rated for 10MWe to 100MWe.
Figure 2: Solar central receiver power plants
Figure 3: Central receiver
Pond thermal solar power plant (s):
Solar pond (Figure 4) is a specially built large shallow reservoir of water. The water gets heated by the sunlight. The bottom of the pond is painted black for absorption of heat. The water is made saline by adding salt. Lower layers are of high salt concentration whereas upper layers are of low salt concentration
Figure 4: Solar pond thermal plant
Operation of Pond thermal solar power plant (s):
Solar radiation passes through the upper layer to the bottom layer. The upper layer provides thermal insulation. Convection of water particles is prevented by the graded salt concentration and of higher density. Hence they remain at the bottom and get heated rapidly due to contact with black bottom. Hot upper layer provides thermal insulation. In a well designed solar pond, the bottom layer temperature can reach up to 95O C whereas the upper layer has the atmospheric temperature. The solar pond therefore acts like a thermal reservoir with large volume.
Applications of Pond thermal solar power plant (s):
- District heating,
- Air conditioning;
- Desalination plants;
- Water heating and
- Electrical power generation.