What are solar power stations?
How we use them to harness the sun's energy sustainably
A solar power plant is a system that converts solar energy into electrical energy in order to produce sustainable electricity. There are different technologies for solar power plants, but in general they use the sun's energy to generate electricity or heat.
Solar power plants can exist in different sizes and shapes, from small decentralised systems on rooftops to large solar power plants that cover large areas of land. The main advantage of solar power plants is that they utilise renewable energy and are therefore environmentally friendly. They play an important role in the reduction of CO2 emissions and the transition to more sustainable energy sources.
The most important technologies for solar power plants are:
Photovoltaics
Photovoltaic systems use solar cells to convert sunlight directly into electrical energy. The solar cells consist of semiconductor materials that capture photons from the sunlight and release electrons, thereby generating electricity. The solar cells are grouped together to form solar modules. These modules can be mounted on various surfaces, be it on roofs, on the ground or in specially designed solar parks. Photovoltaic solar power plants are often grid-connected, which means that the electricity generated on the roof or balcony is fed into the public grid. This allows the electricity generated to be used locally or to be remunerated by the grid operator.
Solar thermal energy
A thermal solar power plant, also known as a solar thermal power plant, uses the sun's energy to generate heat, which is then converted into electrical energy. In contrast to photovoltaic solar power plants, which convert sunlight directly into electrical energy, thermal solar power plants use the sun's heat to drive a work process that ultimately generates electricity.
There are different types of solar thermal power plants, including:
Solar tower power plant
A solar tower power plant uses mirrors, known as heliostats, to focus the sunlight onto a central tower. At the top of the tower is a receiver or absorber that heats a heat transfer medium. This heated medium is fed through pipes to a heat exchanger where water or another fluid is heated to produce vapour. The steam produced drives a turbine which is connected to a generator to produce electrical energy. Solar tower power plants are particularly efficient in sunny areas and can be equipped with heat storage to extend energy production when needed.
Parabolic trough power plant
A parabolic trough power plant uses parabolically shaped mirrors that direct the sunlight onto a central absorber tube. This tube contains a heat transfer medium that is heated by the concentration of sunlight. The hot medium is passed through heat exchangers to heat water and generate steam. The steam produced drives a turbine that is connected to a generator and produces electrical energy. Parabolic trough power plants can be equipped with heat storage units to extend energy production and generate electricity even after sunset.
Fresnel power station
A Fresnel power plant is a solar thermal power plant that uses flat Fresnel mirrors to concentrate the sunlight onto a central absorber. In the centre of this mirror arrangement is an absorber tube with a heat transfer medium. The heat transfer medium is heated by the concentration of sunlight. The heated medium is pumped through heat exchangers to heat water and generate steam. The generated steam drives a turbine that is connected to a generator to produce electrical energy. Fresnel power plants are cheaper to manufacture and can also be combined with heat storage systems.
Solar hybrid power plants
A solar hybrid power plant combines different energy generation technologies to ensure a reliable and continuous power supply. The term "hybrid" refers to the integration of multiple energy sources, often including solar technologies. Here are some examples:
Photovoltaics (PV) and wind power:
A solar hybrid power plant can utilise both photovoltaic modules and wind turbines. This combination enables electricity to be generated around the clock, as wind and sun are available at different times.
Solar thermal energy and biomass:
Another combination could be solar thermal energy with a biomass system. Solar thermal systems utilise solar heat to generate electricity, while biomass systems burn organic materials to generate energy.
Photovoltaics and battery storage:
Here, photovoltaics are used to generate electricity directly from sunlight and surplus electricity generated is stored in battery storage systems. The batteries can then supply electricity when needed, even when the sun is not shining. A popular variant for the home balcony power station.
Solar tower power plant and gas turbine:
A solar tower power plant can be combined with a gas turbine. When the sun is not shining, the gas turbine is switched on to continue generating electricity.
The idea behind solar hybrid power plants is to utilise the advantages of different energy sources and compensate for the weaknesses of a single energy source. This enables a more reliable and stable energy supply, especially when renewable energy sources alone are not continuously available.
When choosing a location for solar power plants, several decisive factors must be taken into account. These include the amount and intensity of solar radiation, climatic conditions, the topography of the terrain, access to power grids, soil characteristics, legal regulations and funding opportunities, environmental impact and access for maintenance purposes. The selection of a suitable location helps to maximise the efficiency and profitability of solar power plants while promoting environmentally friendly and sustainable energy.
