Industry says Germany’s heating energy plans neglect solar thermal’s potential

Cities and towns are leaving most of the large potential for solar thermal heat untapped in their transition to climate-friendly municipal heating, according to Germany’s solar industry trade association, BSW. The solar power industry lobby group cited a recent analysis by Fraunhofer Institute for Solar Energy Systems and sustainability think tank Öko-Institut, which found that 60 percent of municipalities included no solar thermal heating in their 2045 heating targets. 

That is despite solar thermal having the largest theoretical potential of any heat source assessed in the study, including biomass and geothermal, the industry group said. The analysis reviewed 377 completed heat plans, covering 938 municipalities and found solar thermal could potentially supply 457 terawatt hours (TWh) of heat a year. The municipalities’ heat plans project a total heating energy demand of about 121 TWh a year in 2045.  

The authors attributed the low uptake to the mismatch between summer supply and winter heat demand, as well as to competition for land with solar PV panels. But BSW says in a statement that heat from large solar collectors placed in fields could also be stored for winter. It says such storage pits are already in use in pilot projects. Combined with heat pumps, waste heat and other renewables, solar thermal could help to displace fossil fuels and reduce demand for limited biomass during peak heating periods, said BSW, adding it could reduce dependence on energy imports and exposure to volatile fuel prices.  

Germany aims to become climate neutral by 2045. Heating is among the hardest parts of that shift because most buildings still rely heavily on gas and oil. District heating, mostly run by municipal utilities, is central to the plan to decarbonise heating systems. After the government scrapped a requirement earlier this year that obliged new heating systems to run on at least 65 percent renewable energy, utilities say planning remains uncertain. In a survey of 225 municipal utilities, three in four called the 2045 target unrealistic under current conditions.