The market for solar district heating (SDH) has been growing very fast in the decade up to 2016.

In 2016 the Danish capacity of SDH increased by 240 MW.

In 2017 the amount of new SDH dropped with about 80 MW compared with 2016, and the total new installed SDH net capacity was 159 MW. This drop was mainly due to the end of an approximately 10% subsidy scheme at the end of 2016.

In 2018 the net change in SDH capacity was 23 MW.

In 2019 138 MW new SDH capacity was installed.

In 2020 the amount of new SDH capacity dropped below 20 MW and 2021 will most likely be at the same level as 2020.

The market for individual systems has been at a low level, in the range of 2 - 10 MW/year for the last 10 years, with a downward trending market.

The above numbers are based on data from The Danish Energy Agency.

In the period 2021 to 2022, only 2 systems with a total of 10,677 m2 have been installed.

In 2022, a total of 1,607,015 m2 of solar collectors with a capacity of 1,125 MW_th have been installed in Denmark.

In 2023 there are plans to expand one plant and build 2 new solar plants. A total of 11,910 m2 of solar collectors with a capacity of 8.3 MW_th  are planned. 

The spike in electricity prices seen in 2022 has made it clear how the solar thermal heating supply not only provides a low-cost heat, but also helps stabilize the overall heat price. This may represent an increasingly important argument for solar thermal.

From plants having a SDH system the feedback seems positive which is also seen from the interest in expanding their systems where possible. Many DH companies are extending their network connecting more customers to DH. Hence, their heat demand increases, several DH companies are interested in extending their SDH plant to again cover around 20% of the annual demand.

This may represent a small but not completely insignificant market in the coming years. However, in general the low-hanging fruits seem to have been picked in DK and presently there is no outlook towards a SDH market bouncing back.

The prices of HPs and electricity seems to have increased more than the cost of solar collectors so the balance may still tip in favour of SDH in the future. But it has to be more than “break even” compared to alternative options for SDH to be the most favourable solution and without seasonal storage the question of covering the rest of the demand remains for the DH companies even if they would be interested in SDH.

The typical applications are:

• District Heating (5,000 - 160,000 m²)

Flat plate large module collectors are by far the most common collector type used for district heat in Denmark. The collectors are typically installed on the ground in long rows connected in series. The solar heating system normally takes in the return water and heats it up to the desired forward flow temperature. All plants have the solar collectors mounted on the ground. Ground mount foundations can be concrete blocks, concrete foundations or steel foundations.

Typical performance of large solar collector fields in Denmark is approximately 450 kWh/m2/year. This corresponds to an efficiency of around 40%. [Technology Data - Energy Plants for Electricity and District heating generation].

For the large systems for district heating, the main market drivers are the relatively low and stable solar heat price. Heat from large solar fields is competitive with the heat price of gas and some kinds of biomass. And, heat pumps are now very competitive.

The small systems are not as competitive as the large systems, and over the past several years people seem more interested in PV systems.

Since the sale of ArconSunmark in 2020 to GreenOneTEc, there are no longer any manufacturers of large-scale solar collectors in Denmark.

The estimated employment related to the production and installation of solar heating systems in the record year 2016 was approximately 1,300 full time jobs. [According to calculation method given in Fakta om Solvarme, faktablad G07].

Now it is must lower.

Costs of large systems for district heating: In the table below 2015 prices (excluding VAT) of different collector fields installed are seen. The prices include piping in the field, heat exchangers, pumps, control, etc.

Costs of individual systems:

The price for a small domestic hot water system for individual houses, 6 m² collector is between 2,400-4,140 € excluding VAT, depending  on whether it is an existing, renovated or new building. [Technology Data for heating installations]

Medium size hot water system for (e.g., institutions) 100 m² collector:  40,500 € (405 €/m²) excluding VAT. The price is the additional price to install a solar water heater instead of a conventional water heater. [Fakta om Solvarme, faktablad G09a].

The above section " Status of the market for solar thermal systems" was reviewed by: Christian Sjøstrann Jørgensen, Danish Energy Agency, Denmark.

The two largest public funding programs related to technical and societal energy solutions are The Energy Technology Development and Demonstration Programme (EUDP) and Innovation Fund Denmark (IFD). The Danish Energy Agency administrates the EUDP, which supports private companies and universities to develop and demonstrate new energy technologies, including solar heating and cooling. Innovation Fund Denmark supports strategic and applied energy research. Detailed information on the funding programs can be fund on the following webpages: http://ens.dk/en/our-responsibilities/research-development/eudp and http://innovationsfonden.dk/en.

In 2022, EUDP granted three IEA SHC projects, and had a total of seven active solar heating and cooling projects. Detailed information on funded projects and public energy research can be found on https://energiforskning.dk/en/projects. 

EUDP is a general support programme for new and effective energy technologies with a general annual budget for 2022 of about 50 million EUR.

National Research Initiatives and Results

New silicone-based lenses for low cost Concentrated Solar Heat granted by EUDP (2019-2021, grant 5.81 million DKK and a total budget of 9.26 million DKK) will develop and demonstrate more effective, safe and durable lenses for concentrated solar power. Efficiency and durability will be improved by using better materials than the current thermoplastics, and safety and to some degree efficiency will be improved by new lens geometry designs. The responsible company is Heliac.

In 2015, EUDP granted the project Concentrated Solar Power (thermal) combined with biomass fired boiler and ORC plant, (2016-2020, grant 19.91 million DKK and total budget of 86.24 million DKK). The concentrated solar power plant is installed in order to supply heat for an ORC (Organic Ranking Cycle) plant, either alone or together with a Biomass fired boiler. The purpose of the Solar Power plant is to supply the residents in a small Danish city with district heat at a lower cost than the present natural gas fired boilers and to reduce the CO2 impact by less firing with gas and biomass. The responsible company is Aalborg CSP.

Collaborative Research

The Danish Energy Agency/EUDP directly supports or through international cooperation schemes Danish companies, universities, and research institutions participating in international projects. This includes the direct financial support for participating in the TCPs under the International Energy Agency (IEA) and indirectly by means of common calls in the European Union (ERA-net schemes) and Nordic Energy Research.

Heat pumps is still a hot topic in Denmark. Lately a growing interest has been seen in the self-supply of electricity for heat pumps/electric boilers by installing PV/wind turbines with a direct connection.

Danish Energy Agency: www.ens.dk

• Financial support schemes: Minor support to energy savings (including solar) in district heating
• (Building) regulation: Solar thermal counts in the calculation of the energy performance of new buildings and major renovations; these have to fulfill strict requirements for energy use
• RD&D Funding: EUDP
• Quality control:
  1. Installers can join voluntary certification schemes for solar thermal installers: KSO (www.kso-ordning.dk) and VE Godkendelsesordningen (www.ens.dk/forbrug-besparelser/byggeriets-energiforbrug/ve-godkendelses-ordningen)
  2. Most large systems are sold with a guaranteed power performance

At the moment there is no national solar thermal association in Denmark.