In 2020, the German market for solar heat grew by 26% more than any other major solar thermal market around the globe. The total collector area installed in 2020 is around 21.3 million m² and 2.5 million solar thermal systems with a thermal capacity of 15 GW (April 2021; BSW-solar www.solarwirtschaft.de). After the record high in 2008, the capacity fell year after year. In 2019 it was down to 360 MW. The majority of the solar thermal market still consists of collector arrays on single or two-family houses. Overall, it can be observed that there is a rapidly growing market for solar district heating grids as well as for solar process heat systems.
Think big: A growing solar district heating market has been created for several years, this market is picking up speed. Last year, the output of large solar collector arrays feeding into German district heating networks grew by 41%. Germany overtook Denmark in this market segment. A rising awareness of utilities is to be noted. With the commissioning of 31,051 m² of gross collector area, 2020 was the most successful year to date for the solar heating network market in Germany.
Experts predict that 15% of district heating in 2050 could be solar (equal to 30 million m²). Today, 44 large-scale solar thermal plants with a total 106,634 m² are feeding their heat into district heating systems in Germany (database May 2021). 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 at least ambitious, as nearly all heating networks operate at temperatures from 80° to 130°C requiring highly efficient collectors.
Currently, the largest solar thermal installation is 10.4 MW in Ludwigsburg-Kornwestheim. This plant has overtaken the Senftenberg utilities (Stadtwerke Senftenberg GmbH) project as one of the largest installations with vacuum tube collectors worldwide and at the same time the first large-scale installation to supply a public district heating network. Other district heating systems are known in Chemnitz-Brühl, Hennigsdorf in the context of R&D projects. Additional projects that went into operation last year were Bernburg (6.0 MW), Potsdam (3.6 MW), Halle (3.6 MW), Ettenheim (1.2, MW). In 2021, it is expected that the German record holder will be replaced by a significantly larger plant operated by Stadtwerke Greifswald. 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 south-western part of Germany. Another eight plants followed, five of them in the year 2018 (Hengsberg (3,000 m²), Randegg (2,400 m²), Liggeringen (1,100 m²), Ellern (1,245 m²), Hallerndorf (1,300 m²), Moosach (1,067 m²), and Schluchsee in 2019 (3,000 m²).
The market for solar process heat in Germany currently totals approximately 38,800 m² of collector area distributed over 391 systems (March 2021). And 29 installations with 2,949 m² went into operation in 2020 (2 larger plants with 600-750 m², mainly in the range of 20-150 m²). Guidelines and fact sheets are available on the webpage www.solare-prozesswärme.info.The new technical guideline “VDI-Richtlinie 3988 Solar thermal process heat“ was published in the beginning of 2020.
In Germany, 60% of the heating demand and nearly 35% of the final energy consumption are used in applications below 100°C for space heating, domestic hot water and process heating and heating networks.
An ambitious expansion goal of the German Solar Heating Roadmap is to increase the share of solar heating in the requirements and regulations for households from around 1% in 2015 to approximately 8% in 2030. In German industry (heat requirement up to 100°C) the solar fraction shall rise from a little more than 0% today to 10% in 2030.
These are largely determined by the key targets of energy policy: halving primary energy consumption by 2050 compared with 2008 and achieving a renewables ratio of 60% to gross final energy consumption. Through almost complete decarbonisation, the energy sector must additionally help ensure that Germany is largely greenhouse-gas neutral by 2050.