Solar Thermal: Basics

Short: Solar thermal systems use sunlight to generate heat directly for hot water and heating, unlike photovoltaics, which generate electricity. Roof collectors heat a carrier fluid that transfers warmth to a storage tank.

In more detail: A typical system covers a significant share of annual hot water demand, often almost entirely in summer.

In detail

• Flat-plate collector: The most common type, mounted flat on the roof, relatively cheap and robust.
• Vacuum tube collector: Insulates better and reaches higher temperatures, but is more expensive.
• Solar circuit: A frost-resistant carrier fluid circulates between the collector and the heat exchanger in the storage tank.
• Buffer storage: Stores the collected heat so hot water remains available even during low-sun hours.
• Combining with heating: Solar thermal can support heating but usually doesn’t replace it entirely.
• Subsidies: Germany offers government grants that significantly reduce installation costs.
• Distinction from photovoltaics: Solar thermal generates heat, while photovoltaics generate electrical power (waermepumpe, energieausweis-und-daemmung, balkonkraftwerk).