Significant growth in the German solar district heating market in 2019

2020-04-28T16:59:40+02:00Feb 27th, 2020|

Mainly public utilities have installed large solar thermal collector arrays in Germany in the year 2019. The new solar thermal collector arrays for the application in district heating networks cover a total area of around 35,000 square metres. This means that the installed peak power has increased by around 50 percent.

According to the Steinbeis Research Institute Solites in Stuttgart, around 70 megawatts of solar thermal capacity is available for district heating systems in Germany. Some of the new systems are scheduled to start operation in the beginning of 2020. However, as the collector fields have already been erected in 2019, the growth in solar district heating is already prepared. The map below gives an overview of the plants in operation, in planning and in preparation in Germany.

Stadtwerke Ludwigsburg-Kornwestheim, for example, supplied solar heat into the grid for the first time in the course of the first quarter of 2020. With 14,800 square metres, the collector field is currently the largest of its kind in Germany. In Bernburg the situation is similar. Here, the thermal storage is all that is missing for the full operation of the solar thermal collector field that has already been installed in December. The municipal utility of Bernburg plans to finalize it in spring 2020.

“In 2019, mainly municipal utilities in urban areas discovered solar district heating for themselves,” summarized Thomas Pauschinger, member of the Solites management board. Pauschinger considers it a remarkable development that solar heat is now an economically interesting alternative to conventional energy sources for district heating network operators. Key in this development were certainly many successful reference plants and many good arguments as the fact that solar heat supports decarbonising the district heating networks.

Large-scale solar district heating is technically mature. The information of good operating results of the first commercial plants has spread among German utilities. The disadvantage of renewable energies of high investment costs has been addressed and is met with strong governmental support programmes. Thus, the advantage of permanently low operating costs are even more convincing. Furthermore, the decided CO₂ price contributes to further growth and market prospects for large solar thermal systems.

However, the status quo of large solar district heating systems should not be overestimated, Pauschinger emphasizes: “The share of solar heat in district heating sales is still low today. However, we assume a market potential of around 20 gigawatts and expect the market to continue to grow in the coming years”.

Text and map: Solites
Picture: Guido Bröer

SDH prefeasibility studies for Serbian cities

2020-04-28T15:30:11+02:00Feb 19th, 2020|

Renewable district heating has become a hot topic in Serbia. The conference Renewable Energy Sources in District Heating and Cooling, held at the same time as the 50th International HVAC&R Congress and Exhibition in early December in Belgrade, attracted more than 400 attendees.

“The great interest shown by experts and the media during the December conference helped us a lot in forging new relationships with high-level representatives for municipalities, local governments and public utility companies to raise the profile of SDH,” said Bojan Bogdanovic, who launched the event. He is also Principal Fund Manager of Renewable District Energy in the Western Balkans (ReDEWeB), a programme supported by Austria and implemented by the European Bank for Reconstruction and Development (EBRD).

ReDEWeB has already supported several prefeasibility and feasibility studies on solar district heating in Serbia and Kosovo. The most advanced project in terms of planning is the one in the Serbian town of Pancevo, where the two-year test of a 906 m² solar field put up in January 2017 has convinced the local council of the benefits of solar heat. Together with the Kotež power plant, the field supplies hot water to about 2,200 citizens. The council then commissioned the installation of 198 large collectors, mounted onto the roof of the Kotež plant, to meet an even higher share of the hot water needs in the district heating network with solar energy. The council members are now looking into adding an SDH system with seasonal storage. A prefeasibility study prepared by the Austrian engineering firm Solid mentions a 35,000 m² field of collectors, 150,000 m³ of storage volume and a 15 MW absorption heat pump.

All presentations from the 50th International HVAC&R Congress have been posted online and are available for download here.

Source and full article:
Picture: Milica Knežević for SMEITS©2019

Solar Heat for Cities – IEA brochure and infographics

2020-04-29T13:40:26+02:00Jan 15th, 2020|

Solar heat improves energy security, keeps heat costs stable for at least 20 years and cuts air pollution in towns and cities. To encourage more mayors, local council members and municipal utilities to look into this cost-effective solution, researchers working on IEA Task 55, Towards the Integration of Large SHC Systems into District Heating and Cooling Networks, published the brochure Solar Heat for Cities in November.

The SHC Task 55 of the International Energy Agency aims to develop technical and economic requirements for the commercial market introduction of solar district heating and cooling (DHC) for a broad range of countries. The activities aim to improve technological know-how, market know-how and understanding of the boundary conditions as well as to provide expert know-how for project initiation and implementation and for training. This consumer promotion material includes 11 infographics that illustrate solar district heating (SDH) technologies, their advantages and market growth. The files, available in English, German and French, can be downloaded in JPG or PDF format and can be used free of charge in third-party publications.

“SDH markets are growing in Denmark, Germany and China, and new markets are starting to emerge, for example, in France, Italy, Poland and Spain,” explained Sabine Putz, Chair of Task 55. “With this brochure, we aim to address new investors and local decision-makers.” The case studies into successful SDH projects shown in Solar Heat for Cities brochure are real-world testimony to the benefits of solar district heating for municipalities. Satisfied SDH investors explain why they chose a specific mix of technologies, including solar energy, to reduce their dependence on fossil fuels or lower heat prices for their customers. The logic behind this approach is: “If it works for them, it could work for us too.”

The brochure showcases nine SDH systems built in Austria, China, Denmark, France, Germany, Latvia and Serbia. The infographic above shows a usual set-up and main elements of SDH systems.

The brochure and the information charts were sponsored by the following Task 55 participants, in cooperation with the Belgian-based European Copper Institute: Solites (Germany), Solareast Arcon-Sunmark Large-Scale Solar Systems Integration (China), Aalborg CSP (Denmark), newHeat (France), Savosolar (Finland) and Greenonetec (Austria).

Download the SDH infographics here.
Download the ‘solar heat for cities’ brochure here.

Images: IEA SHC Task 55
Source and full article:




15 MW SDH plant inaugurated in Latvia

2020-04-28T14:15:01+02:00Oct 27th, 2019|

On 12th September, district heating operator Salaspils Siltums inaugurated a 21,672 m² solar field and a wood chip boiler, put up in the middle of the woods near the town of Salaspils, Latvia, to meet 90 % of the demand from the local district heating network.

The inauguration came after a three-week test run of the solar district heating plant and its new 8,000 m³ storage tank. The system was installed by the Latvian-based company Filter, which signed an EPC contract with Salaspils Siltums in August 2018. The collectors were delivered by the Danish manufacturer Arcon-Sunmark.

Salaspils Siltums started planning the solar system after a neighbouring cogeneration plant was shut down. “We have been working on this project since coming back from a visit to Denmark, where we attended the solar district heating conference 2016 in Billund (which was held under the H2020 Project SDHp2m). The aim is to lower our carbon footprint and become less dependent on fossil fuels,” said Ina Berzina-Veita, Managing Director of Salaspils Siltums. After conducting a feasibility study in January 2017, the utility was able to secure EU funding in February of the same year. The EU’s Cohesion Fund has contributed EUR 2.73 million to the EUR 7.08 million invested in the solar field, the storage tank and the 3 MW biomass boiler. The project could reduce the company’s district heat tariff by at least 5 %, utility staff confirmed. Salaspils Siltums is also about to sign additional heat contracts with new customers.

Salaspils Siltums is a relatively new utility, founded as recently as 1996. Since 2010, the company has grown rapidly but has kept its focus on eco-friendly solutions. Each year, it supplies about 65 GWh to 17,000 customers. 85 % of all households in Salaspils use district heating already.

Picture: Salaspils Siltums

Video: Vision 2050 for District Heating and Cooling by Euroheat & Power

2020-04-28T14:01:38+02:00Oct 22nd, 2019|

Within their vision 2050, Euroheat & Power has published this video “Decarbonising DHC For Our Cities” for the promotion of district heating and cooling (DHC) . Besides the animated video, different city representatives shared their experiences and plans.


Find out more about the Vision 2050 on

Source: Euroheat & Power



Solar thermal is on the rise in German district heating networks

2019-08-01T12:03:08+02:00Jul 31st, 2019|

34 large solar thermal plants with a total capacity of 44 megawatts and a gross collector area of 62,700 square meters are currently integrated into district heating grids in Germany. The industry, which discussed its perspectives at the conference “Forum Solare Wärmenetze” in Stuttgart in June 2019, expects accelerated growth in the coming years and anticipates a fiftyfold market increase in the long term.

In 2019, additional 23 megawatts with a collector surface of 33,000 m2 are expected to be built. Germany’s district heating suppliers have discovered the sun, most of all the public utility company Stadtwerke Ludwigsburg-Kornwestheim (Baden-Württemberg), which is currently building the largest German solar thermal plant with 14,800 m2 collector area. So far, the Stadtwerke Senftenberg (Brandenburg) has kept the German record. Last year, Stadtwerke Senftenberg harvested 4,720 megawatt-hours for their district heating network from the 8,300 m2 of solar collectors.

For the next five years, Dirk Mangold, head of the Steinbeis Research Institute Solites, expects the number of plants to be roughly doubled to 70 large solar systems with a tripling of capacity to 140 MW. “This figure is calculated from ongoing projects and concrete feasibility studies, whereby we have calculated the respective probability of realization as a factor”, explained Mangold at the conference. Compared to the official national targets, as set out in the Federal Government’s energy efficiency strategy for the building sector, the current very positive market development can only be regarded as a start. The scientist emphasized: “By 2050, the Federal Government would like to massively increase the contribution of solar thermal energy to district heating. With a share of 15 percent, this corresponds to 12 terawatt-hours per year. This requires an installed capacity of around 21 gigawatts, i.e. a collector area of around 30 million square meters. We therefore need an additional 1 million square meters per year. That means that the roll-out has to increase by a factor of 50 compared to this year!”

Solar district heating systems are developing positively in all market segments. At present, mainly large systems for urban district heating are in preparation for the coming years.

A factsheet with more information on the current market status of solar heating in Germany can be found here.  (German language).

Text: Thomas Pauschinger, Solites; Picture: Eins Energie in Sachsen GmbH &Co. KG; Graph: Solites



New handbook on upgrading district heating grids in Europe published

2019-07-23T11:43:04+02:00Jul 9th, 2019|

Based on the experience from companies in 6 different european countries, this handbook elaborates technical and non-technical subjects related to upgrading the performance of district heating systems. An introduction into implementation of solar district heating can be found within the large collection of content.

District Heating (DH) systems present a high potential for the transition of the heat sector, both technically and organizationally. They allow the integration of renewable energies, they serve to improve the overall energy efficiency and they facilitate sector coupling (coupling between heating, electricity and mobility). However, many DH systems need to be continuously upgraded so that they are efficient and have zero (or close to zero) emissions and thus, contribute to mitigate climate change. Hence, more than one year was needed to put all the knowledge of the Upgrade DH consortium partners on paper and to elaborate a handbook with the title “Upgrading the performance of district heating networks – Technical and non-technical approaches; A Handbook”. Experiences from different European countries were used to describe the technical and non-technical approaches in DH upgrading processes. The aim is to inform stakeholders such as decision makers, politicians, utilities, operators, end consumers, or potential developers of DH systems, about upgrading opportunities. Thereby, the ambition of the handbook is not to provide a detailed technical guideline for technicians, but rather to give an overview on upgrading options.

The handbook is available for free as pdf document at



Video: How to improve the acceptance of solar thermal in district heating systems

2019-07-23T11:59:44+02:00Mar 1st, 2019|

A new video has been created to help the public to distinguish between domestic hot water (DHW) applications and solar district heating (SDH) as well as to understand the existing experience and applicable costs in the sector.

In France, solar thermal is mainly developed for domestic hot water (DHW) of individual or collective residences. Solar thermal implementation in DH networks is not known by the public. A national survey carried out during the first phase of the SDHp2m European project has shown that for a large majority of actors solar thermal is always associated to DHW. For the others, SDH is perceived as an expensive and experimental renewable energy.

During the exchanges with the regional project stakeholders, a particular attention was paid to the need to communicate through elected officials. Indeed, if they are informed upstream of a DH project, they can accelerate and promote the implementation of solar thermal in the future network project, showing a strong political will. Citizen acceptance is also an important aspect to develop.

In order to address these challenges, a guide and a video were created to inform about SDH. The video  includes interviews with different stakeholders from the region (local public authorities, energy managers), working to develop these networks. This type of video is initiated for the first time in France and, as a complement for the guide, it will allow to change the public opinion on solar thermal.

Click here to watch the video.

Source: Mathieu Eberhardt, Auvergne Rhône Alpes Énergie Environnement



Sun meets 90 % of district heat demand in Tibet

2019-07-25T12:00:47+02:00Dec 17th, 2018|

After the Solar Academy of the IEA SHC Programme in Lianyungang (China), District Heating experts visited the newly constructed solar district heating plant in Tibet

The high point of the international SDH gathering was the tour of a solar district heating installation that had been planned by Chinese-Danish joint venture Arcon-Sunmark Large-Scale Solar Systems Integration. At Sunrain’s invitation, 18 task members flew to Tibet to take a look at the solar district heating plant in Langkazi, a town in the south of the region, where the venture has been installing 22,275 m2 of flat plate collectors and 15,000 m3 of pit storage. The entire system would be finished soon and be up and running before the end of the year, said Leo Holm, who works at Arcon-Sunmark and guided the Task 55 members around the site.
It is supposed to contribute 90 % of the heat to the new district heating network in Langkazi. Via a 65 °C supply line and a 35 °C return line, the grid reportedly supplies thermal energy for 100,000 m2 of residential floor space. The joint venture has manufactured and delivered the collectors and supervised the installation of the SDH plant. A 3 MW electric boiler guarantees backup energy in times of low irradiation.
The facility is part of a larger endeavour to popularise renewable heating in Tibet. Feasibility studies have been conducted in over 20 of the region’s counties and cities, and Tibet’s local government has approved funding for five of them.

Image: Solites

Source: Bärbel Epp




Latvian city invests in solar district heating

2019-07-23T14:25:41+02:00Nov 14th, 2018|

The first half of 2019 will mark the launch of a milestone project on solar district heating in Eastern Europe. The public utility which serves the Latvian town of Salaspils, near Riga, plans to install 21,672 m2 of collector area (15 MWth) to provide heat for its modernised, efficient district heating network.

The solar field will be connected to an 8,000 m3 water storage tank, from which thermal energy will be injected into the network. The project, which will also include a wood-chip boiler with 3 MWth of capacity, had been planned jointly by Arcon-Sunmark, a Danish supplier of solar thermal devices, and Filter, a heating and cooling company based in Latvia. Salaspils Siltums provides 85 % of the town with a population of about 17,000 people with district heat. A 7 MWth wood-chip boiler is currently the main source of 60,000 MWh of thermal energy a year. The plans for the 15 MWth solar system state that it is expected to contribute 12,000 MWh or 20 % of the total at some point between July and September next year. Reportedly, the utility will receive funding from the European Union for buying the system.

“We have been working on this project since we attended a district heating conference in Denmark in 2014. The objective is to reduce our CO2 footprint and become more independent of fossil fuels,” Ina Berzina-Veita, who is a Member of the Board of municipal utility Salaspils Siltums, was quoted as saying in a press release which Arcon-Sunmark sent out in the middle of October.

Over the last years, the utility has optimised its district heating network. It replaced underground pipes with pre-insulated ones and revamped the central boiler. The current supply and return temperatures of 65 °C and 45 °C, respectively, will make for a highly efficient flat plate collector array, the operation of which will be very effective.

Image: Arcon Sunmark

Source: Bärbel Epp


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