2019 was another year of market decline in the German solar thermal sector, only 0.51 million m² of collector area were installed, roughly as much as in the previous year. The total collector area installed in 2019 is around 21 million m² in approximately 2.4 million solar thermal systems with a thermal capacity of 14.8 GW (April 2020; BSW-solar www.solarwirtschaft.de).
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 an increasing market for solar district heating grids as well as for solar process heat systems. Think big: there has been a growing solar district heating market for the past several years. This market is picking up speed although many more projects are needed. Experts predict that 15% of district heating in 2050 could be solar (around 30 million m2²). In 2019, new projects added 26 MW. There is a rising awareness by utilities. Today, 38 large-scale solar thermal plants with a total capacity of 53 MWth are feeding their heat into district heating systems in Germany.
Broad marketing measures were done within the context of the project “SOLNet4.0”. Integration of solar thermal systems into heating network systems is expected to expand but remains ambitious, as nearly all heating networks operate at temperatures from 80° to 130°C requiring highly efficient collectors. The largest solar thermal installation in Germany is a 10.4 MW systme is in Ludwigsburg-Kornwestheim. This plant has overtaken the Senftenberg utilities (Stadtwerke Senftenberg GmbH) project as one of the biggest 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 in Chemnitz-Brühl, Hennigsdorf are part of R&D projects.
Other projects that began operating last year: Bernburg (6.0 MW), Potsdam (3.6 MW), Halle (3.6 MW), Ettenheim (1.2 MW). Also, so-called solar assisted bioenergy villages - smaller communities in rural areas - have 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).
At present more than 300 systems for process heat are in operation. Twenty installations with 1.8 MW went into operation in 2019. The number of applications is growing due to several years of continued financial support for process heat plants. A spirit of optimism is caused by CO2 pricing schemes that will be introduced in 2021. Most of them have been installed in SME (two third in the range of 20-40 m², one third 40-100 m²). In 2018, there was a trend towards larger installations. In 2019, 38% of the subsidised solar thermal installations were installed in pressure regulator and gas control stations and 25% for drying processes in agricultural sector. Guidelines and fact sheets are available on 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 become largely greenhouse-gas neutral by 2050.