The town of Bracht in Germany is embarking on an innovative project to provide heating throughout the winter using solar energy. This initiative aims to deliver approximately 80°C hot water to every household year-round. A total of 180 buildings will be heated using solar energy, operating at a cost comparable to gas heating but with zero maintenance expenses. Additionally, insulation upgrades in many buildings over 40 years old are expected to further reduce costs.
The heat storage system employs a technique developed in Denmark known as Pit Storage. A 14-meter-deep pit with a volume of 27,000 m³ will store hot water from summer to winter. The pit will be lined with durable, waterproof materials and topped with floating insulation. During the first year, some heat will be absorbed by the surrounding soil, but heat loss will decrease in subsequent years.
To collect solar energy, 5,060 solar panels will be installed, transferring the heat to the storage pit. In colder months, two heat pumps will activate to raise the pit’s water temperature to 30°C. Additionally, a biomass boiler will provide supplementary energy during extreme winter conditions, when temperatures drop as low as -15°C.
The project’s total cost is estimated at €16.5 million, with €10.5 million allocated to energy production and distribution and the remainder directed towards the heat storage system. The energy supply is expected to be sourced 68% from solar energy, 26% from biomass, and 6% from heat pumps, ensuring a sustainable and efficient solution for year-round heating.