Municipalities Plan for Only a Small Share of Solar Thermal Energy in Heating Networks

November 3, 2026

Source: E & M powernews

A study by Fraunhofer ISE and the Öko-Institut shows that, despite its potential, solar thermal energy has so far played only a minor role in municipal heating plans.

Solar thermal energy has so far played a minor role in the municipal heating plans of German cities and municipalities. This is the finding of the study “Municipal Heating Planning in Germany – Evaluation of Completed Heating Plans in the KOMpare Project (as of 07/2026)” by Fraunhofer ISE and the Öko-Institut. According to a recent press release, the researchers analyzed 377 heating plans covering a total of 938 municipalities. In these plans, the municipalities estimate the potential of solar thermal energy at approximately 457 billion kWh per year. This places the technology in first place among the energy potentials surveyed.

In the scenarios for heat supply in 2045, however, solar thermal energy appears much less frequently. “The sun ranks at the very top in terms of potential, but far down in concrete heating plans. That doesn’t add up,” explained Carsten Körnig, CEO of the German Solar Industry Association (BSW-Solar), in a press release dated November 2. According to the report, less than 40 percent of the municipalities surveyed include this technology in their plans. Among municipalities that provide details on the future generation mix of their heating networks, solar thermal energy accounts for only 3.6 percent.

According to a survey conducted by the Competence Center for the Municipal Heat Transition (KWW) among 778 cities, municipalities, and counties, 40 percent of the participating municipalities are now in the implementation phase of their heating plans. A year earlier, this figure stood at just 17 percent. Another 32 percent are currently developing their heating plans, while 18 percent are making the necessary preparations. This brings decisions regarding the future generation structure of heating networks to the forefront. BSW-Solar is therefore calling for solar thermal energy to be given greater consideration both in the development of municipal heating plans and in the transformation plans of network operators.

According to BSW-Solar, there are approximately 3,800 district heating networks nationwide. This compares to about 75 large-scale ground-mounted solar thermal systems. The association sees additional opportunities for deployment, particularly in the integration into existing networks and in the planning of new service areas.

The economic viability of solar thermal systems depends, among other things, on the availability of suitable land, the temperature level of the heating network, investment costs, and the integration of heat storage systems. While collector fields deliver high yields primarily in the summer, heat demand rises during the heating season. Daily and seasonal storage systems can partially offset this temporal shift. In combination with heat pumps, waste heat, and other generation technologies, solar thermal energy can be integrated into various district heating concepts.

Association Calls for Early Land Acquisition

BSW-Solar therefore calls for securing suitable land at an early stage when implementing municipal heating plans and for examining economically viable solar coverage rates. In addition, planners should examine the integration of daily and seasonal storage systems. The association views reliable subsidy conditions and shorter approval procedures as further prerequisites for expansion.

In addition to reducing CO2 emissions, BSW-Solar points to reduced dependence on fuel imports and energy price fluctuations. Solar thermal systems require no fuel for heat generation during operation. As a result, they can reduce the consumption of fossil fuels and the demand for biomass. “Solar heat requires neither pipelines nor oil tankers. It is generated directly on site and makes municipalities, businesses, and consumers less dependent on international energy markets,” said Körnig.

From the association’s perspective, the key question now is whether municipalities and district heating operators will take the identified solar thermal potential into account in their investment decisions. The results of “KOMpare 2026” show that there is a discrepancy between the calculated potential and the contribution to heat generation planned to date in this country. However, the potential figures alone do not yet indicate what proportion could actually be tapped under the respective local and economic conditions.

Author: Heidi Roider