21.07.2026
Solar & geothermal energy – making clever use of sustainable heat
The sun delivers vast amounts of energy every day, while the earth provides reliably steady temperatures – two sources of energy that are perfect for sustainable heating. Solar thermal energy systems harness the sun’s rays directly, heating water and feeding it into the heating system. Geothermal energy systems, on the other hand, utilise the earth’s stored warmth to heat buildings evenly. Both methods reduce reliance on fossil fuels and make a valuable contribution to climate protection.
Special demands of solar and geothermal systems
Unlike traditional heating systems powered by gas or oil, which tend to operate fairly uniformly, solar and geothermal systems have their own specific requirements:
Solar thermal energy systems
- Highly fluctuating temperatures: Values can fluctuate dramatically between the midday sun in summer and cloudy autumn days.
- Risk of stagnation: If not enough heat is drawn off, the collector can stop circulating, leading to extremely high temperatures. Reliable circulation protects the system and extends its service life.
- Efficiency in partial load operation: Especially in spring and autumn, solar thermal systems do not operate at full capacity. Pumps that allow external performance control are particularly advantageous here.
Geothermal energy systems
- Constant but low temperatures: At sufficient depth, the ground delivers steady values, though these are much lower than those from fossil fuel heating systems. For heat pumps to work efficiently, a continuous and even pumping is needed.
- Long running times: Geothermal energy systems often run for many hours at a time, so energy-saving, quiet and durable pump technology is especially important.
- Adaptability to different sources: Whether flat plate collectors or downhole heat exchangers, each source has slightly different operating conditions. Flexible pump control makes deployment much easier.
Solar and geothermal energy systems demand a high degree of flexibility, efficiency and reliability from pumping technology. Only when heat is transported reliably can these systems fully realise their ecological and economic potential.
Pump technology – the key to efficiency
At the heart of the system is the circulation pump. It’s the engine that transports heat from the collector or downhole heat exchanger throughout the house. Modern pumps offer several crucial benefits:
- Flexible control: They automatically adjust their output to current conditions – whether dealing with fluctuating solar radiation or the steady demands of geothermal use.
- High level of energy efficiency: A particularly low Energy Efficiency Index (EEI) ensures the pump itself uses minimal electricity – a significant factor, especially with long running times.
- Easy operation: LED displays, clear control knobs and setup assistants make operation straightforward.
- Future-proof: Various control modes – from constant pressure to special modes for solar and geothermal use – make the technology versatile for many applications.
Practical examples from everyday life
The Williams family has upgraded their heating system with a solar thermal system. On sunny days, the collected heat is fed straight into the storage tank. The pump ensures consistent circulation, even when temperatures change quickly due to clouds or during spring and autumn. The result: lower energy consumption on sunny days and noticeably reduced heating bills.
In a newly built residential area, many homes rely on geothermal energy. Downhole heat exchangers provide continuous warmth, used in combination with a heat pump. To distribute the energy efficiently, the pump runs for many hours each day – energy-saving, quiet and reliable. For residents, this means a cosy warm home at predictable operating costs and a significant contribution to climate protection.
Conclusion
Whether it’s solar or geothermal heat – both sources are efficient, climate-friendly and future-proof. For the technology to work reliably, pump systems must be flexible, energy-efficient and easy to use.
That’s exactly where the Wilo-Varios PICO-STG comes in: a pump for all applications – whether heating, cooling, solar or geothermal energy. It is a universal solution for almost every application in detached and semi-detached homes. For users and professional installers alike, it means a product that suits most situations – practical, efficient and future-proof. It’s especially valuable for emergency call-outs: with just one type of pump on the vehicle, a wide range of applications can be covered – and sourcing spare parts is much easier.
