There are two ways to use solar energy: photovoltaics and solar thermal energy. Solar is the general term for photovoltaic and solar thermal systems, as both use the power of the sun to generate energy.
First things first
What is the difference?
Photovoltaics generate electricity, solar thermal energy generates heat. Both terms are referred to as solar.
How does solar thermal energy work?
Solar thermal energy uses solar heat to heat water. Efficient for heating and hot water.
How does photovoltaics work?
Sunlight activates solar cells, which generate electrical current through the movement of electrons.
What is a solar system?
A solar system is therefore a system for converting solar energy into electricity or heat.
What is the difference between photovoltaics and solar thermal energy?
The main difference between photovoltaics and solar thermal energy is the form of energy generated. Photovoltaic systems generate electricity, solar thermal systems generate heat energy. Both systems use solar energy as an energy source and are therefore called solar systems.
Photovoltaic systems use solar modules to convert solar energy into electricity. Solar thermal systems use solar panels and a pipe system to generate heat energy.
PV modules and solar thermal collectors on the roof
More differences We have summarized them in the following table:
| Characteristic | solar thermal energy | photovoltaics |
| energy production | warmth | Electricity |
| Cost | small amount | high |
| economy | low to moderate | high to very high |
| efficiency | mediocre | small amount |
| space requirements | small amount | high |
| installation effort | small amount | high |
| life | high | high |
| maintenance | very low | small amount |
| storage | mediocre | high |
| versatility | mediocre | high to very high |
| environmental friendliness | high | high |
| funding | Yes | Yes |
How does a photovoltaic system work?
One photovoltaic system converts solar energy into electricity. The solar cells in the solar modules are responsible for this conversion. The sunlight stimulates the electrons in the solar cells, which creates direct current. An inverter then converts this into alternating current, which can be used in the home.
Optional for the efficient operation of a photovoltaic system are a electricity storage and a energy management systemThe power storage unit stores excess solar power during the day for later use. The energy manager controls the excess solar power within the photovoltaic system. It ensures higher self-consumption and efficient use of solar power.
What are the advantages and disadvantages of photovoltaics?
Solar energy is available free of charge and almost inexhaustible. Photovoltaics not only saves electricity costs, but also reduces carbon dioxide emissions. Although the initial costs are quite high, there are numerous funding options. Investing in photovoltaics is worthwhile because you become more independent of electricity suppliers and fluctuations in electricity prices.
| Advantages of Photovoltaics | Disadvantages of Photovoltaics |
| free and renewable energy source | high acquisition costs |
| lower electricity costs | weather-dependent power generation |
| lower dependence on electricity suppliers | seasonal fluctuation - more yield in summer, less in winter |
| long service life of over 30 years | |
| can be combined with heat pump and electric car | |
| reduction of CO₂ emissions | |
| feed-in tariff | |
| funding opportunities |
How does a solar thermal system work?
One solar thermal system consists of two main components: solar collectors and a buffer tank. Solar collectors absorb the sun's rays and convert them into heat. This is absorbed by a glycol-water mixture and stored in a buffer tank via a pipe system. This provides the heat energy either for hot water preparation or to support the heating system.
The solar controller is the main control unit for a solar thermal system. It detects the charging capacity in the storage tank. It switches the solar pump on and off to transfer the heat from the collectors to the storage tank. Solar thermal systems also have expansion vessels to compensate for volume fluctuations and pressure changes.
What are the advantages and disadvantages of solar thermal energy?
Solar energy is also available as free and renewable energy for solar thermal systems. It helps to reduce heating costs and CO₂ emissions. Although solar thermal systems are cheaper to purchase than photovoltaics, the payback period is also longer. Solar thermal systems cover the entire hot water requirement between April and September. For the rest of the year, however, you are dependent on another energy source.
| Advantages of solar thermal energy | Disadvantages of solar thermal energy |
| free and renewable energy source | limited storage capacity |
| lower heating costs | weather-dependent heat generation |
| can be combined with other heating systems | seasonal fluctuation - almost no heat generation in winter |
| long service life of over 30 years | slow payback period of up to 20 years |
| reduction of CO₂ emissions | |
| funding opportunities |
