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.

The most typical applications are still small systems for domestic hot water and space heating for single and two-family houses. Growing markets with great potential are in the field of solar process heat for industrial applications and solar district heating systems and smart solar thermal grids (see above).  In the last years, several large solar thermal systems were installed as demonstration projects:

• The largest solar thermal system in Germany is 14,500 m² in Ludwigsburg Kornwestheim followed by Senftenberg 8,300 m² (see above).

• In Crailsheim, 7,500m² of flat plat collectors for district heating and a 39,000 m³ seasonal borehole thermal energy storage were installed. The collectors will be replaced by collectors with a higher efficiency within the next years.

• Büsingen (near Konstanz and close to Switzerland) is Germany´s first solar assisted bioenergy village.  More than 1,000 m² CPC vacuum tube collectors are integrated in a newly installed heating network combined with biomass heating. Heat energy price is less than 40 €/MWh.

• In Grafenhausen one of the biggest process heat systems for the brewery Rothaus went into operation in in 2018 with 1,000 m² vacuum tube collectors.

Attractive feed-in-tariffs for PV are today less profitable than there were years ago. In combination with the German BEG, an attractive programme for funding energy efficient buildings, this framework helped the market growth.

New pricing of CO2 emmissions: The Climate Action Programme 2030 was adopted in November 2019. One major element of the Climate Action Programme 2030 is a proposal for a new national carbon pricing system that covers the transportation and building sectors. The national emissions trading system will be launched in 2021 with a fixed price system. A price per ton CO2 will be set at political level. The fixed price will initially be €25 per ton CO2, and will rise to € 55 per ton by 2025.

The German solar thermal industry had a turnover of approximatley €0.70 billion (database 2016). According to BSW-solar´s strategy document “Solar Thermal Roadmap”, it could even rise up to €3 billion by 2030. This will only be the case, however, if system prices fall by 50% by 2030.

There are approximatley 140 medium-sized manufacturers and suppliers as well as 86 distributers of solar thermal components.

The export quota was found to be greater than 50%. The German value creation rate is 75% (database 2016).

The market leaders for large-scale systems for solar heating network integration and process heat integration are the companies Ritter XL Solar GmbH and Viessmann. Solar thermal systems are marketed tripartite, which in comparison to PV, is one of the reasons that the consumer prices are much higher than the manufacturing costs.

The German solar thermal industry employed around 20,000 people in 2016, including installers and distributers (database 2016).

The costs for solar thermal energy in Germany range between 10-15 Cent/kWh for hot water and space heating in single and multi-family houses and 5-10 Cent/kWh for large- scale systems. The specific system costs run between 500-1,100 €/m² (database 2016).

Costs differ between small and large-scale solar systems as well as between systems for domestic hot water and space heating or large systems with and without seasonal storage. For large solar process heating systems and solar assisted heating grids, costs from 4-7 Cent/kWh have been realized and 5-3 Cent/kWh could be reached. The main target for solar thermal energy is to reach gas-parity.

Two ambitious R&D projects focused on cost reduction are “KOST” and “TEWISOL”. The projects' objectives were to reduce the solar heat generation costs by approximately 40% to increase the competitiveness of solar thermal energy versus other heat generation technologies, primarily achieved through standardization. Results were discussed in 2019 and contributed to SHC Task 54: Price Reduction of Solar Thermal Systems. Teh University of Kassel presented its learning curve of solar thermal systems in Germany at the Solar World Congress 2017 in Abu Dhabi: learning rate of DHW systems is 18% and of Combisystems 8%.

The goal of the German solar heating roadmap is to reduce the costs of a solar heating system by a total of 50% by the year 2030. Cost reduction  of solar thermal systems is one of the main targets of R&D.

Other key topics are:

• Pre-configured and standardized and simplified quick assembly of the components to reduce installation costs and installation errors
• Advanced building integration and system integration of solar heat and solar power (PV, PVT)
• Solar active houses with higher (up to 100%) solar fraction for heat and power for single and multi-family houses

In Germany, all types of solar technologies for buildings and industry are subject to research, demonstration and market activities. Continuity in national funding schemes for R&D is guaranteed by the 7th Energy research programme of the German government. The building and neighborhoods sectors as well as the trade commerce services and industry sector comprise a broad range of R&D topics.

In the course of sector coupling, buildings and neighborhoods will in the future have to interact more with the power and transport systems because linking the building infrastructure with energy supply in the transport sector, using vehicles as storage units for locally produced renewable energies, for example, can contribute to improving the climate footprint and energy efficiency.

With regards to the energy transition initiated by the German Government in 2011, the main objective is to reduce primary energy demand, to generate most of the demand on site and to reflect energy efficiency in the building's whole life-cycle. The grid friendly net-zero-energy-building is the main focus. The goal requires a proper building design, the integration of different new advanced technologies and the optimized control of the heating system.

Passive houses are popular, approximately 25,000 units were built in Germany according to the passive house standard (ig-passivhaus.de) and 10% of these certified by the passive house institute (database 2016).

By the end of 2016, more than 2,200 solar active houses, “Sonnenhäuser” or “sunhouses”, had been built in Germany.

Additionally, the "efficiency house plus" initiative is worth mentioning: grid connected PV provides electricity for a heat pump-based heating system and power for appliances. The main problem is the higher primary energy demand as this concept needs electricity from the grid in wintertime.

Again, attractive feed-in-tariffs for PV are today less profitable than there were years ago. In combination with the German BEG – an attractive programme for funding energy efficient buildings -  this framework has helped the market grow.

More and more federal states and cities are implementing “solar obligations”, in many cases PV obligations with strong impact for solar thermal technology.

New pricing of CO2 emmissions: The Climate Action Programme 2030 was adopted in November 2019. One major element of the Climate Action Programme 2030 is a proposal for a new national carbon pricing system that covers the transportation and buildings sectors. The national emissions trading system will be launched in 2021 with a fixed price system. A price per ton CO2 will be set at the political level. The fixed price will initially be €25 per ton CO2, and will rise to €55 per ton by 2025.

There is no information available at this time.

For the last few years there is a new subject of focus, “economic viability”, within the accompanying research model projects (construction costs, building usage costs, and lifecycle costs as well as the associated optimization potential in regards to minimized CO2 emissions).

German energy research is a strategic element of German energy policy and is indispensable for the long-term success of the energy transition.

Since 2014, the funding is concentrated in the new Federal Ministry for Economic Affairs and Energy. R&D for solar thermal and for solar buildings is part of the Energy research Programme of the German Federal Government (www.bmwi.bund.de).

In April 2016, the Federal Ministry for Economic Affairs and Energy together with the Federal Ministry of Education and Research started the R&D Programme for "Solar buildings and energy efficient cities/ areas" with a budget of €150 million for 3 years. Six milestone projects have started in city districts.

The 7th Energy Research Programme defines the current principles and priorities for Federal Government for an environmentally-friendly, reliable and affordable energy supply funding for innovative energy technology. In September 2018, the Federal Cabinet adopted the 7th Energy Research Programme entitled “Innovations for the Energy Transition”. It contains the guidelines for energy research funding in the coming years. In addition to specific technologies, funding is made available for overarching, cross-sector issues such as energy efficiency, reduction of consumption, sector coupling and digitisation. This contributes to ensuring a holistic funding approach.

Thanks to the innovative funding format of ‘living labs’, the energy system of the future can already be tested today. The results and experience serve as a blueprint for the actual practical implementation. At the same time, more funding is planned to be made available to start-ups, which is essential to provide fresh impetus to the energy transition. It is essential that research is closely linked at the European and international levels. For this reason, cooperation with international organizations will be expanded and scientific exchanges will be promoted. Furthermore, the improvement of the capacity to export and of the competitiveness plays an important role.

Since the launch of the 1st Energy Research Programme in 1977, the Federal Government has invested around €12 billion to fund over 17,300 non-nuclear energy research projects (database 2018).

Active solar thermal systems for different solar thermal applications such as water and space heating and cooling, solar district heating and storages are included in the sub-program “Energy optimized buildings and areas”, solar process heat is includes in the sub-program “commerce, trade, services sector and industry”.

In 2019, we looked back on 25 years of R&D in solar energy. R&D started with the support programmes “Solarthermie 2000” and “2000plus” with pilot and demo systems. In recent years, it has delivered impressive results.

In November 2015, on the side-lines of the Paris Climate Change Agreement (COP21), the initiative Mission Innovation was established, whose members now include 23 states and the European Union. The member states, including Germany, have committed to double public investment in research and development for clean energies within five years.

Market: Solar water and space heating, large solar systems > 100 m² collector area, low energy buildings, solar active houses with solar fraction >50%, solar process heating systems for different industries 

Demonstration: Solar process heating, large scale solar thermal systems with seasonal and multifunctional storages, solar district heating systems, smart solar thermal grids, solar thermal absorption and adsorption cooling for small and medium outputs, and combined solar/CHP-systems.

Concentrating collector systems for process heating and cooling (PTC, Fresnel), solar facades, and intelligent control systems for solar buildings.

Research:       

• New collector and storage materials; Cost reduction for solar thermal systems through standardization and plug&play installations
• System integration for solar process heat
• Advanced building integrated photovoltaics and solar thermal power
• Advanced thermal storages with higher storage capacity (PCM/PCS, TCM); PVT-systems with optimized heat and power output

“Energiewende” means a drastic transition of the energy system. The goal of reducing CO2 emissions by at least 80% by the year 2050 relative to 1990 levels can only be reached if a clear shift to renewable energy sources in the heating sector combined with a reduction of the energy demand occurs.

After having made major progress in many areas, the energy transition is now entering a new phase. While the initial main concern was with expanding renewable ener¬gies and energy-efficient technologies, greater focus will now be placed on systemic issues.

The goals are part of the National Action Plan of Energy Efficiency (NAPE) and the Energy Efficiencies Strategy for Buildings (ESG) of the German government. The directices, German Energy Saving Ordinance (EnEV) and the German Renewable Energies Heat Act (EEWärmeG), merged into a new “Gebäudeenergiegesetz”.

Solar heating is a natural and sustainable form of heat production. And, it should be an integral part of the heat supply system in the majority of residential buildings and areas. In the field of industrial process heat, solar heating contributes significantly to reducing the energy costs of companies. The strategic goal of the German Solar Heating Roadmap of the BSW-Solar (2012) was able to achieve tremendous growth up to the year 2020 and then a breakthrough by 2030.

The Federal Ministry of Economic Affairs and Energy (BMWi) coordinates the federal energy research.

Project Management Jülich (PtJ) supports its clients in the German Federal Government and the federal states as well as the European Commission in implementing their research policy goals with a focus on project funding. This includes SHC on advanced new concepts and technologies to improve the energy efficiency and lower the specific primary energy demand of buildings in R&D projects for energy efficient and solar buildings and active solar thermal systems and thermal energy storages.

The Federal Government has amalgamated the funding of research, development and demonstration measures for energy-efficient buildings and neighbourhoods in the research initiative, ENERGIEWENDEBAUEN (Energy transition construction). In addition to ongoing calls for proposals and specialist portals, this also includes its own research network.

A new attractive incentive scheme was implemented the end of 2019. Since the beginning of 2019 funding for solar process heat systems was reorganized within the framework of "Energy Efficiency and renewable process heat in economy“.

Feasibility studies and the realization of new generation of district heating systems (systems with supply temperatures of 20 to 95°C,  50% renewable energy) are subsidized within the frame of “Wärmenetze 4.0” (www.bafa.de/DE/Energie/Energieeffizienz/Waermenetze/waermenetze_node)

R&D funding is part of the 7th Energy Research Programme “Innovations for the energy transition” of the German Federal Government.

The solar industry is represented in different associations:

• German Renewable Energy Association (BEE)
• German Solar Industry Association (BSW)
• German Industry Association of Heating Technologies (BDH)
• German Heat and Power Association (AGFW)

For research, important actors are:

• Renewable Energy Research Association (FVEE) (www.fvee.de)
• Working Group on  Solar Thermal Technology  (www.forschungsnetzwerke-energie.de/energiewendebauen) (formally the German Solar Thermal Technology  Platform; DSTTP)

• German Sustainable Building Council (DGNB – Deutsche Gesellschaft für Nachhaltiges Bauen e.V.)
  Founded in 2007 by 16 initiators from various subject areas within the construction and real estate sectors. Their goal is to promote sustainable and economically efficient building even more strongly in the future
• Passive House Institute (PHI) 
  Independent research institute that has played an especially crucial role in the development of the Passive House concept - the only internationally recognised, performance-based energy standard in construction
• German Energy Agency
  Focuses on energy efficiency, renewable energy sources and intelligent energy systems at the interface between politics and business
• Deutsche Bundesstiftung Umwelt DBU (German Federal Environmental Foundation)
  One of Europe's largest foundations and promotes innovative and exemplary environmental projects 

Federal Report on Energy Research: transparency for the Federal Government’s funding policy: The report is published every year and serves to give an extensive overview over the Federal Government's research promotion policy in the field of energy. Progress made and current trends in the field of research promotion are presented in the report in a transparent manner. The figures on project funding contained in the Federal Report on Energy Research are also made transparent by EnArgus, the central information system on energy research of the Federal Ministry for Economic Affairs and Energy.

The most important source for information and dissemination of research projects in solar thermal and solar buildings: https://projektinfos.energiewendebauen.de/.

German website on solar process heat: www.solare-prozesswärme.info.

Update of the website for seasonal storage (www.saisonalspeicher) is planned in 2021.