In 2022, 91,000 solar thermal systems with 710,000 m² gross area were installed the Germany. This amounts to an increase of the solar thermal power by 460 MW. The total collector area installed in 2022 amounts to 22.1 million m² in approx. 2.6 million solar thermal systems with a thermal capacity of 14.4 GW (Bundesverband Solarwirtschaft e. V. (March 2023) https://www.solarwirtschaft.de/presse/marktdaten/).
After the record high in 2008, the newly installed solar thermal capacity has been decreasing each year. In 2019, it was down to 360 MW. Since then, it started to slightly increase again, reaching its latest highpoint in 2022, with a 12% increase compared to 2021.
The share of renewable energy sources in final energy consumption for heating and cooling in Germany increased more in 2022 than in previous years, reaching 17.4 percent in 2022, compared to 15.8 percent in 2021. Between 2000 and 2022, the share of solar thermal energy grew from 2 to 5 percent of the total renewable heat in Germany (https://www.umweltbundesamt.de/themen/klima-energie/erneuerbare-energien/erneuerbare-energien-in-zahlen?sprungmarke=waerme%23waerme).
The majority of the solar thermal market still consists of collector arrays on single or two-family houses. Solar thermal is not only integrated in existing gas heating systems but a combination of solar thermal and heat pump systems or pellet heating systems is chosen to achieve a full coverage of renewable energies. There is also a growing market for solar district heating grids and a high potential for solar process heat systems. The demand from public utilities and municipalities is growing, especially with respect to megawatt-scale solar cogeneration plants for feeding into local and district heating networks. Low prices of down to 4 Ct/kWh are one of the driving factors. In 2022, energy providers added eight new heating plants with a total collector capacity of about 30 MW. This corresponds to around 6 % of the solar thermal additions.
Solar District Heating
The solar district heating market has been growing for several years and is picking up speed. Today, there are 49 large-scale solar thermal plants with a total of 146,206 m² in Germany (https://www.solare-waermenetze.de/2023/03/28/solare-waermenetze-in-betrieb-2023/). 33,879 m² of new solar collector areas have been built last year, leading to an increase of the total collector area by 30 percent compared to the previous year's level. The calculated thermal output of district heating solar thermal systems in Germany has thus reached the three-digit megawatt range for the first time, as up to 102 megawatts of solar thermal energy can be fed into district heating.
The strong growth in 2022 is mainly due to the commissioning of the largest solar thermal system in Germany in Greifswald (M-V) with 18,732 m² of collector area alone. This plant has overtaken the former largest plant of Ludwigsburg-Kornwestheim utilities with 14,800 m2. In addition, the third largest system in Lemgo went into operation in 2022 (9,118 m², NRW).
Experts estimate that 15% of district heating in 2050 could be solar (according to 30 million m2). Broad marketing measures were done within the context of the project “SOLNet4.0” and follow up project “SOLNetplus”. Integration of solar thermal systems into heating network systems is expected to expand but remains still ambitious, as nearly all heating networks operate at temperatures from 80° to 130°C requiring highly efficient collectors.
In the past, so called solar assisted bioenergy villages - smaller communities in rural areas- switched from de-central heating oil boilers in every single house to small district heating networks, using renewable energy sources. Solar thermal plants provide the entire heating demand in summer, often combined with large biomass boilers for the winter periods. In 2013, the first solar district heating plant of this type went into operation in the village of Büsingen in the southwestern part of Germany. Another eight plants followed, five of them in the year 2018: Mengsberg (2,950 m²), Randegg (2,400 m²), Liggeringen (1,068 m²), Ellern (1,245 m²), Hallerndorf (1,304 m²), Moosach (1,067 m²), Schluchsee in 2019 (3,364 m²).
The market for solar process heat in Germany currently totals around 450 systems (2022). In 2022, only 5 new installations went into operation. Solar thermal energy thus remains a niche application in the industrial environment despite good funding conditions. Smaller plants are mainly built in the commercial sector. The largest system currently under construction is the 2,145 m² system for the gas pressure control system for among others the EUGAL natural gas pipeline. Plants with concentrating collectors have a promising range of applications in this field, but there is no plant on the market so far. Guidelines in addition with fact sheets are available on the webpage http://www.solare-prozesswärme.info.