Support joint marketing efforts for solar district heating

2022-02-24T13:53:10+01:00Feb 24th, 2022|

At a workshop set to take place on 4 and 5 April in Graz, Austria, the IEA Solar Heating and Cooling Programme will launch a new research platform about Efficient Solar District Heating Systems, also called Task 68. This three-year programme will focus on medium-high temperature feed-in and digitalisation. Regarding the latter, the task members will take an especially close look at advanced control strategies, automated monitoring and open data, with the aim of exchanging best practice examples. For the first time, a solar heat technology provider will lead the knowledge-sharing activities.

“We will have a very strong focus on a systems approach. We would like to work on efficient hybrid solutions that use solar energy combined with other technologies to provide the supply temperatures required by a heat network,” explained Viktor Unterberger, who will chair Task 68 and is a senior researcher on Automation and Control at the Austrian BEST – Bioenergy and Sustainable Technologies centre of excellence.

Unterberger is being supported in his efforts by experienced IEA SHC solar heat strategists: Sabine Putz, of SOLID Solar Energy Systems, Austria, and Magdalena Berberich, of Solites, Germany, will both be subgroup leaders. Both were also members of previous Task 55 on Large Solar District Heating and Cooling Systems. A new subgroup leader will be Joakim Byström, of Swedish company Absolicon. For the first time, a technology provider will head the dissemination activities within an IEA SHC task. This will bring a new level of quality to outreach efforts, especially because of Absolicon’s wealth of experience in marketing and lobbying.

Stop burning wood in summer

One of the things that Absolicon has been campaigning for in Sweden is an SDH support scheme. The country in northern Europe has already had a fairly green district heating sector, with wood meeting more than half of all district heating needs nationally. But now, Sweden has a supply chain problem when it comes to local, sustainable biomass, as the country also wants to replace transportation fuel and high-temperature heat sources in industry with biomass-based energy carries.

Absolicon’s slogan “Stop burning wood in summer” has therefore been well received by policymakers. “The Green Party have put our call for a 50 % subsidy scheme for large solar district heating plants high on their agenda,” said Byström. “We are now pointing to the example of a raised budget for large-scale solar heat plants in Austria while also calling for financial support for feasibility studies.”

Biomass and solar for efficient district heating

Of course, Unterberger knows that SDH marketing slogans need to be adapted to different national contexts. In countries where biomass energy is not used as widely as in Sweden, biomass boilers and solar could be a suitable combination for providing green heat. One crucial argument for the promotion of solar district heating could be a high dependency on gas imports from geopolitically critical countries, such as Russia and Algeria.

Infocharts in general play a key role in Absolicon’s communications strategy. The company has created a number of easily accessible materials to explain the benefits and features of solar district heating to newcomers:

To learn more about how to join Efficient Solar District Heating Systems, do not hesitate to contact Viktor Unterberger at

Source and full article:
Picture: Absolicon Solar Collector

Lessons learned from three years promoting SDH in the Western Balkans

2022-02-24T13:58:53+01:00Jan 12th, 2022|

The interest in solar district heating has increased significantly in Serbia since the European Bank for Reconstruction and Development (EBRD) started to finance prefeasibility studies for SDH plants in January 2019. Furthermore, Serbia adopted a Renewable Energy Law in April 2021 which includes an ambitious mechanism to support the implementation of renewable heating and cooling capacity.

The Northern Serbian city of Novi Sad (see photo) is one of the cities with a rather modern district heating system and a committed municipal council which is pushing the planning for a multi-MW solar heat plant. In this interview, Bojan Bogdanovic, Principal Fund Manager of the Renewable District Energy in the Western Balkans (ReDEWeB) programme, tells lessons that have been learned from three years of promoting solar district heating in the Western Balkan countries.

What is the current status of the planning process for SDH in Novi Sad?
Bogdanovic: In September 2021, the municipality accepted the prefeasibility study’s recommendations and decided to proceed and conduct a feasibility study together with the EBRD. The solar heat solution currently being discussed should be of more than 65,000 m2 and have seasonal storage. This decision has been announced already via social media and we are waiting to receive the formal request for cooperation from the municipality. The city on the Danube has a rather modern district heating grid, which is very suitable for the feed-in of solar heat.

What are the convincing arguments for solar heat as an option to make the example central heat supply system in Novi Sad greener?
Bogdanovic: One of the major advantages are the zero local emissions of solar heat plants, considering that most cities in the Western Balkans have an air quality problem and therefore biomass plants are not always seen as an ideal solution for greening the district heating grid. Another important advantage is the stable and predictable heat prices throughout the lifetime of the facility, enabling the municipal utility to manage the system in an economically efficient way in the short, medium and long-term.

How good are the conditions for solar district heating in the Western Balkan countries?
Bogdanovic: The Western Balkans is one of the southernmost European regions with significant solar radiation and large district energy systems. Some of them have a high degree of modernization and digitalization, achieving operating parameters that are very suitable for solar. The average fluid temperatures in the return line are often below 50 °C because of efficient temperature regulation in the buildings, good hydraulic balancing and an increasing percentage of renovated buildings.

Project development times for solar district heating are generally long. What does your experience in the Western Balkans indicate?
Bogdanovic: Five years usually pass between the initial discussions and the start of the ground work. That´s why it is great news that the donors from the Austrian and Swiss governments have extended the ReDEWeB programme for two more years until December 2024.

What role does the distance between the collector field and the feed-in point play when searching for land? 
Bogdanovic: The distance between the land dedicated for the solar collector field and the feed-in point in the existing heat network, which needs to have a large enough dimension, or the heating centre is important for the feasibility of the project. The larger the scale of the project and the amount of heat generated, the longer a justifiable connection pipeline can be. Heat losses are not the key issue here but the CAPEX that needs to be invested in constructing the connection pipeline.

What do you expect from the new Renewable Energy Law in Serbia?
Bogdanovic: The law is a great step forward for SDH in Serbia. It stipulates that the government must establish a support mechanism to cover a certain share of the investment costs of renewable heating and cooling projects. What is important is that the law guaranties that the district energy utilities must purchase surplus heat from both private and public operators of renewable heat plants. The Ministry of Mining and Energy is currently drafting all the sub-laws necessary for the full implementation of the bill and it is expected that this process will be complete in early 2022.

Organisations mentioned in the interview:

Source and full article:

Spain: Solar district heating on the starting blocks

2022-02-24T14:07:01+01:00Dec 16th, 2021|

The Spanish solar district heating market is still in its infancy. Among the 500 district heating networks in operation across the country totalling more than 1.6 GWth only seven use solar heat, according to the Association of District Heating and Cooling Companies (ADHAC).

Project developers report that there are barriers relating to unclear urban construction regulations when planning solar district heating plants. The good news, however, is that solar district heating is one of the eligible technologies within the new national grant scheme PREE, which has a budget of EUR 400 million until 2023.

In Spain, despite much more abundant solar resources, this technology is still in its infancy. According to Miguel Angel Armesto, ADHAC President, only 1.5 % of the district heating and cooling grids include solar technology. “Solar thermal requires more space and there is not currently a direct incentive for solar district heating,” explained Armesto.

According to Pascual Polo, President of the solar thermal association ASIT, “Today, the potential for district heating in Spain is underestimated and limited in areas with natural gas networks. Solar district heating is an innovative and promising solution that can be more cost-effective than gas district heating.”

Urban construction regulations thwart SDH

In Spain there have already been some promising SDH projects planned, for example in 2018 the Spanish city Alcalá de Henares announced their plan to build a renewable district heating grid for 12,000 inhabitants. However, according to Teodoro Lopez, head of DH Ecoenergías, the former promoter of the Alcalá project: “There is a lack of clarity in the urban installation rules. In Spain, we do not have a specific framework that allows district heating and, depending on the council, this is a disadvantage against other technologies.

However, he seems to be positive about the future. “We are already installing a heat network in Palencia town and expect to start two other new grids in 2022 in Castille Leon” reported López.

EUR 400 million available

According to Polo, “renewable heat is undervalued in terms of its potential within the political and social discourse.” The head of ASIT believes that it will be very difficult to achieve a renewable share of 42 % in energy end-use by 2030, up from 17 % today, unless the use of renewable heat and district heating is boosted. The 42 % target is part of the National Integrated Energy and Climate Plan in Spain and is coordinated with European targets.

ADHAC´s President Armesto is optimistic that the new Energy and Efficiency Building Rehabilitation Programme (PREE) will support investments in district heating and solar district heating technology. The programme provides EUR 400 million of direct subsidies for new solar water heaters, biomass boilers, and heat pumps until 3rd December 2023.

Websites of organisations mentioned in this news article:

Programme For Building Rehabilitation (PREE) can be found here.

Source and full article:

“Renewable heat generation should be privileged in the Building Regulations §35”

2022-01-12T15:09:43+01:00Oct 7th, 2021|

There is a lack of land available in Germany for solar district heating systems due to the complexity of the land-use plan procedure. Bene Müller, Co-Director for Sales and Marketing at solarcomplex AG in southern Germany thinks that renewable district heating plants should be privileged according to paragraph 35 of the German Building Regulations, otherwise decarbonisation of the heating sector will not be possible.

Mr Bühler of the company Ritter XL said in an interview: “The German solar local heating market could be larger if sufficient land area was available”. Do you agree with him?
Müller: Yes, certainly. But fundamentally, enough land exists, it is just not easily available. The land for large solar heat projects has to be found right next to built-up areas. Agricultural land already competes with building land. In addition, solar district heating plants or infrastructure for regenerative heat generation in general are generally not privileged.

What would privileging mean and how could it be realised?
Müller: Paragraph 35 of the Building Regulations lists the types of project that can be privileged for planning and realisation on the edges of towns and communities. All building projects for the general supply of electricity are covered in these paragraphs. Wind power has also been included since 1997.
Here, federal policy makers are called upon to include general regenerative heat supply systems. For planners this would mean that planning permission is still required but no land-use plan procedure would be necessary before this. This hurdle certainly needs to be abolished.

What tasks are planners faced with in a land-use plan procedure?
Müller: The land-use plan procedure is very complex. It includes glare analysis reports, environmental aspects and the tedious assessment of alternatives. The latter is particularly obstructive because one can be happy to have found a suitable site at all. Having to prove that the site is better than others, even though these are purely fictitious, is an unnecessary hurdle. If district heating systems are to become the norm, the authorisation procedures need to be simplified.

Have you also experienced these difficulties in finding suitable land areas for wind turbines or PV?
Müller: Yes, there are also difficulties there, but the situation is different because with photovoltaics and wind turbines there is more freedom in selecting the location. A solar collector field always has to be constructed near to the heating network in order to minimize the losses in the connecting pipework.

Despite these planning hurdles, solarcomplex now operates 18 CO2-optimized heating networks in Germany. What is your recipe for success?
Müller: We now have many reference projects, so word has got around among mayors and local councillors. We often get a follow-up project from a nearby town when the heating network in the neighbouring community is in successful operation. However, the economic arguments are also important. We don’t make an extra charge for the building costs, which means that any heating customer can be connected to the heating network free of charge, and we offer competitive prices for the heat.

How do you achieve inexpensive heat prices despite the high initial investment costs?
Müller: Mostly we use waste heat from biogas plants, which we get for nothing from the farmers. The operators of the biogas plants receive a higher cogeneration bonus if the waste heat is utilised. In networks without any waste-heat potential we have constructed solar thermal plants, which also provide heat at a stable price of 2.5 EUR-ct/kWh, which is still very cheap. One should not forget that around half of the cost of the heat is dependent on the capital costs for the high investment in the new heating network. For each local heating network several million EUR are buried in the ground!

So what exactly is your business model?
Müller: We plan, build and operate a heating network in the streets of a community, with which we conclude a concession contract as a basis. Then we supply as many buildings as possible, including public once, with renewable heat. Nobody is obliged to connect to the system, we simply need to be economically attractive. Of course, we conclude heat supply contracts with as many customers as possible, before we start the construction work.

The interview was conducted by Bärbel Epp.

Source and full article:

Picture: Solarcomplex

Costs of solar heat projects are falling

2021-08-17T16:31:17+02:00Jul 16th, 2021|

The IRENA report Renewable Power Generation Costs in 2020 illustrates how the competitiveness of solar and wind power improved dramatically in the decade 2010 to 2020.

Thanks to the support of the Solar Payback project, the flagship publication now also includes a chapter on Renewable Heat Costs, highlighting cost trends for solar district heating systems across the world.

Written by Michael Taylor and his team at the International Renewable Energy Agency (IRENA), it shows how even existing coal plants are increasingly vulnerable to being undercut by renewables. Taylor was deeply appreciative of the cooperation between IRENA and Solar Payback during the data gathering process: “We see real added value from this approach, as our data is going to help inform policy makers and will assist modelers trying to incorporate different solar heat technologies into their scenarios,” he said.

In all, 32 solar heat project developers and technology suppliers and four funding agencies from around the world contributed to creating a database full of cost and performance data on over 1,760 projects totaling 935 MWth.

The newly added chapter highlights how strongly system costs fell in Austria and Germany in the last years. From 2013 to 2020, the 89 projects listed for Austria saw a 55 % decrease in weighted-average total installed costs. The 209 systems built in Germany showed a 45 % drop between 2014 and 2020. A key cost reduction factor in Austria in 2019 and 2020 was the much larger average size of installations put up during that period, according to IRENA. In Germany, reductions were the result of a maturing supply chain.

One country that stands out in the cost data analysis is Mexico, where rich solar resources and strong competition between mature suppliers helped push the levelised cost of heat (LCOH) to as low as 3.9 USD-cent/kWh in 2020.

The IRENA document also highlights the economies of scale achieved by experienced manufacturers and suppliers operating in Europe’s district heating market. The whole report is available here.

Source and full article:
Image: IRENA/Solar Payback

SDH factsheet database is online

2021-08-18T11:29:39+02:00Jun 1st, 2021|

The IEA Solar Heating and Cooling Programme has just launched a database containing a substantial number of fact sheets about solar district heating technologies, best practices and markets. 29 documents, written by the most experienced SDH researchers and practitioners from China and Europe, are available online.

The creators collaborated on the four-year IEA SHC Task 55 – Towards the Integration of Large Solar Systems into District Heating and Cooling Networks. The new online resource offers valuable insights into SDH research and showcases by providing information on feasibility studies, the monitoring of large solar fields, the design of hybrid technologies and business models. Some highlights of its content are:

  • Country Reports: Spanning 34 pages, fact sheet D-D4 gives a detailed overview of seven prospering SDH markets, namely Austria, China, Denmark, France, Germany, the Netherlands and Sweden.
  • Solar Heat for Cities: Fact sheet D-D2, an investor brochure, showcases nine SDH systems built, with satisfied investors explaining their reasons for choosing a mix of technologies, including solar energy, to reduce their dependence on fossil fuel or be able to lower the heat prices they charge to customers.
  • On-site tests of collector arrays: Fact sheet B-D1.2, on the other hand, compares methods to monitor the performance of an installed solar field. This paper helps manufacturers, plant designers and operators choose a suitable method for giving them the information they need. Testing procedures are based on measurement data for an entire solar field, excluding distribution pipes, and make use of a solar field model that includes corrective factors, to account for variables influencing the yield.
  • Going big on SDH: Fact sheet D-D1 analyses business models and technology solutions for large solar heat systems with high solar fractions in cities.

The SDH marketing package also includes 11 infographics illustrating the advantages of the technology and the policies in place to support it. The files, available in English, German and French, can be downloaded in JPG or PDF format and be used free of charge in third-party publications. All 29 fact sheets are available for download at

Source and full article:
Image: IEA SHC Task 55

SDH plant performs well in Swiss winter conditions

2021-08-18T09:52:00+02:00Mar 25th, 2021|

A new solar district heating plant in Geneva, Switzerland, is basking in the limelight of Swiss politics, with environmental minister Simonetta Sommaruga personally attending the start-up of the system at the end of February 2021. The 816 m2 solar field consists of special high-vacuum flat panels supplying heat to Geneva’s district heating network at a temperature of 85 °C, even in winter.

The installation helps meet the objectives of Geneva canton’s Energy Master Plan 2020-2030, approved in early December 2020. The SDH system (operated by the SIG utility) was designed by Geneva-based TVP Solar to deliver 516 MWh a year, which corresponds to a specific annual yield of 632 kWh/m2. This is significantly higher than the typical Danish SDH plants which produce between 321 kWh/m2 to 500 kWh/m2 per year, the average being 409 kWh/m2, according to one IEA SHC publication.

The plant is one of several innovative clean energy systems SIG has implemented in the last years. The solar field, which was mounted onto a roof at SIG headquarters in Vernier’s Le Lignon district in Geneva canton, is equipped with 80 performance-tracking sensors.

A press release put the demonstration project’s budget at CHF 2 million, of which CHF 800,000 was spent on the solar field. “Including the CAPEX of the solar field, you get to a heat price of about 70 CHF/MWh over 20 years. That’s a very competitive proposition for zero-carbon heat in Switzerland. Across Geneva, clean biofuel energy costs 100 CHF/MWh,” noted Guglielmo Cioni, Vice President of Business Development at TVP Solar.

The distinctive characteristic of this particular SDH plant is its high output in wintertime. To reduce energy losses, especially during cold winter days, the absorbers are located inside an evacuated casing. “Another advantage of high vacuum insulation is that it takes very little time to ramp up the temperature in the morning. The solar field reaches the required 85 °C in just a few minutes, even if it is partially covered in snow,” Cioni said about his company’s experience of operating the plant during the first weeks after start-up.

TVP’s most important panel-related patent describes a new method for joining glass plates and metal frames to ensure a high enough vacuum inside the collectors. Thanks to the small size of the contact areas between the internal absorber and the metal frame, heat losses are reduced to a minimum, but enough heat is transferred to the casing for the snow to start melting.

Organisations mentioned in this article:

Source and full article:
Image: SIG

Spotlight on SDH potential in Germany, the Netherlands and Austria

2021-03-11T20:28:45+01:00Feb 2nd, 2021|

Solar thermal will have a key role to play in growing western Europe’s solar district heating markets over the next decades.

Dutch, German and Austrian SDH experts updated attendees during a workshop organized by IEA SHC research platform Task 55 on the current situation and the potential in their respective markets. For example, the collector area installed in Germany, they said, could triple from about 100,000 m2 used in 41 systems today to more than 300,000 m2 by 2025 (see the chart above). As announced in December 2020, the country’s soon-to-be biggest SDH plant will have 13 MWth, a good deal more than the 10 MWth installation in Ludwigsburg (10 MWth). This new plant will be put up in Greifswald, in northeast Germany, and is scheduled for completion by 2022.

Luuk Beurskens, of TNO, Netherlands’ organization for applied scientific research, presented the initiative for a Solar Thermal Roadmap (“Aanzet tot Routekaart Zonnewarmte”). The authors of the 32-page report looked at what experts had to say about the solar thermal market in the Netherlands, and what actions need to be taken for a strong growth in the years ahead. The Dutch building sector alone could potentially see its solar capacity grow from 1.2 PJ in 2019 to 35 PJ in 2050. And adding seasonal heat storage could raise the country’s solar potential to as much as 54 PJ, which would be enough to meet 26 % of the total demand for thermal energy by 2050. The assessment shows important potential contributions to be provided by individual residential systems (34.3 PJ) and new solar district heating networks (18.8 PJ).

Hamid Aghaie, of the Austrian Institute of Technology (AIT), spoke about a possible evolution of Austria’s DH sector and the role of solar thermal over the next decade. Currently, 60 % of the country’s district heat is generated by CHP plants, though heat pumps and solar thermal are expected to increase their share in the market.

Using open-source dispatch and the investment model Balmorel, AIT estimated what proportion of Austria’s DH capacity solar thermal systems could provide by 2030. The results show that the share of solar heat in DH networks could increase by a factor of 60, from essentially zero in 2018 to 3.8 %, in 10 years. At the same time, demand for district heat would grow from 23 to 28 TWh.

Source and full article:

Graph: Solites

Quick Check BIOSOL: New tool helps utilities make the right choices

2021-03-11T20:21:49+01:00Jan 27th, 2021|

As early as November 2020, the national association Austria Solar put a new decision-making tool called Quick Check BIOSOL on its website. In essence, the program helps plant owners to find out whether their district heating networks could benefit from solar heat integration.

At a German-language webinar following the upload, Austria Solar’s Managing Director Roger Hackstock explained how the tool works. It requires only a couple of basic system parameters to determine whether solar collectors can supply as much energy in summer as the biomass or fossil fuel boilers grid operators have in place today.

According to March 2018 data, 1,546 of Austria’s 2,108 biomass plants used for heating are also run in summer despite some drawbacks. For one, the devices produce soot, which hampers efficiency and increases wood chip consumption. Switching to solar thermal can solve these issues, reduce operation cost, and lower air pollution. But instead of immediately turning to detailed – and costly – feasibility studies on solar district heating sites and systems, stakeholders can now use Quick Check BIOSOL for a first, free analysis of whether a retrofit is worth the effort. The tool was developed in partnership with several Austrian experts and was sponsored by solar thermal system supplier Gasokol.

The tool utilises only a dozen parameters, including buffer tank volume, annual district heating demand, usable roof surface, grid temperature in summer, boiler type (biomass or fossil) and type of auxiliary heating (heat pump, waste heat or CHP system). Aside from that, the tool will automatically fill in some values, for example, the average collector yield. Almost immediately after entering the parameters, a note pops up, indicating a system’s potential for solar heat integration. This means the tool shows how much collector area is needed to replace a boiler partly or entirely in summer and how much land the collectors require if roof space is limited. In addition, Quick Check BIOSOL provides recommendations e.g. on how to reduce grid temperatures and more.

You can find a recording of the webinar and Hackstock’s presentation at:
Austria Solar’s Quick Check Biosol:
Source and full article:
Photo: Solid

World´s largest solar district heating plant with concentrating collectors

2021-03-11T15:38:03+01:00Sep 28th, 2020|

The Chinese parabolic trough collector manufacturer Inner Mongolia XuChen Energy has successfully operated a huge solar district heating plant since 2016 in a village near Baotou in Inner Mongolia, an autonomous region of China.

The installation in Baotou consists of two fields of parabolic trough collectors, a 22,000 m2 rooftop field on XuChen’s factory hall next to the company’s headquarters and a 71,000 m2 system put up at ground level. The 93,000 m2 (65 MWth) SDH plant is the world’s second-largest after Denmark’s Silkeborg (110 MWth) installation but the biggest using concentrating collectors. It provides 500,000 m2 of residential buildings, buildings in a neighbouring industrial zone and a shopping mall with solar heat.

The 93,000 m2 solar plant is part of the government’s green heat policy to improve air quality in China’s northern provinces and phase out coal boilers. This policy is part of the overall trend to improve social living conditions and provide affordable housing which is summarized under the slogan “livelihood”- a term created by the Chinese government. Wang confirmed that the installation of the solar plant in Baotou is the first livelihood project introducing solar space heating to the region. ‘The government has completely taken over the RMB 0.55 billion in capital costs for the solar field, including the storage tank and the newly built heat network,’ Wang explained in an interview with This 100 % public subsidy was what prompted XuCheng’s investment in a collector factory in the same city. XuChen, founded in spring 2016, also invested Renminbi (RMB) 1.05 billion, i.e., USD 154.7 million, in putting up headquarters as well as a 50,000 m2 factory for parabolic trough collectors in Baotou’s green industrial park.

Solar heat transported to nearby heat consumers by truck

Wang said that he has observed an increase in solar heat demand from China’s northern provinces. He added that surplus heat generated in summer, when none of the buildings connected to the SDH system require space heating, is transported by truck to nearby consumers, including hotels, swimming pools and spas. As China’s green heat policy requires the phase-out of coal boilers and because heat pumps rack up high electricity bills, purchasing solar heat from Baobou’s SDH plant is an economically viable option for those requiring large amounts of heat all year round.

Another huge solar district heating system is currently being built by XuChen in Han Dan, in the north of China. According to Wang, this plant will provide heat to a new all-weather, four season ecotourism vacation and leisure park. Due to the green heat policy of the government the construction of the leisure park would not have been possible without a source of clean energy for heating, in this case provided by SDH.

Sources and full article:
Photo: XuChen

Go to Top