Status of Solar Heating/Cooling and Solar Buildings - 2020

Status of the Market for Solar Thermal Systems

Market Size and Trends

Although solar thermal receives the highest Renewable Heat Incentive (RHI) tariff (see section on Support Framework), the number of installations in the UK have been falling in recent years. In 2019, just over 5,000 m2 of solar water heating collectors were installed, down from 90,000 m2 at its peak in 2010 (Solar Trade Association, 2017).

Data on the contribution of solar thermal to the UK energy system is available from the Digest of United Kingdom Energy Statistics (DUKES). Since the launch of the UK Domestic Renewable Heat Incentive scheme in April 2014, around 8,850 domestic solar thermal installations have been accredited (to December 2017), which equates to around 48,434 MWh of solar thermal heat.

Typical Applications and Products

Typical solar thermal applications in the UK are domestic hot water systems for houses and swimming pool heating. Domestic hot water systems are generally forced circulation systems with 150 to 250 litre tanks and 2 to 5 m2 of flat plate or evacuated tube collectors. Flat plate collectors account for the larger share of the market (80 %); many of these systems are roof-integrated which are designed to replace roof tiles.

Several metal cladding companies offer active solar air heaters as part of their product portfolio. Since their introduction to the UK market in 2005, approximately 14,000 m2 have been installed, with the largest being a 4,334 m2 collector installed on the Marks & Spencer (M&S) distribution centre at Castle Donington.

Main Market Drivers

In the case of new build housing, building regulations focus on carbon emissions rather than energy consumption; with the availability of relatively low carbon gas delivered through a comprehensive national network and relatively high carbon electricity (as assumed in the Standard Assessment Procedure for Energy Rating of Dwellings), small solar photovoltaic (PV) systems can often help meet carbon emissions targets more cost effectively than solar thermal and so have become the favoured approach when selecting a solar technology to help meet regulations, except for off the gas grid where solar thermal is a more competitive solution.

Another significant challenge for solar thermal water heaters in new housing in the UK is the popularity of wall hung instantaneous natural gas combination boilers (combi-boilers), which do not require a hot water tank. New UK houses are the smallest in Western Europe (Royal Institute of British Architects, The Case for Space: the size of England's new homes) which can make installing a new hot water cylinder a challenge. Solar thermal systems with small hot water tanks which are designed to pre-heat the cold water supply for a combination boiler are available in the UK. Another challenge is the competition for roof space from the increased deployment of roof-mounted PV. Several UK companies offer PV power diverters, which will divert excess PV generation into a hot water tank immersion heater.

With regard to the market for retrofit of renewable energy systems within existing UK houses, one of the significant market drivers has been a proportion of home-owners wanting 'to do the right thing'. However, for a variety of reasons (which include the availability of a Feed-in-Tariff, system simplicity and effective marketing) solar PV has proven to be a more popular choice within this sector of the market than solar thermal.

Public opinion of solar thermal, and renewable energy in general, is very positive in the UK. The BEIS Energy and Climate Change Public Attitudes Tracker (PAT), which has been tracking public opinion on energy related issues since March 2012, has shown consistently that around 80% of the public support renewable energy.

Public awareness for solar thermal in particular is strong (highest among the renewable heat technologies), however, only 7% of those surveyed, and who were aware of renewable heat, are considering installing solar thermal in the near future. The main reasons for not installing solar thermal were the perception of high installation cost (26 %) and survey respondents not owning their own property (25 %).


The UK is home to AES Solar, which has been manufacturing flat plate solar collectors in Scotland since 1979. Other suppliers, including major wholesalers of plumbing products, offer imported products or own-label products made overseas. Solar thermal systems are generally sold either by the manufacturer to installers (to consumers) or via wholesalers, who sell to installers, who then sell to consumers.


No reliable information is available on the number of jobs in the solar heating/cooling sector, but given the small size of the current UK market employment levels are likely to be modest (less than 500).


Trade prices for domestic hot water system kits (collectors, storage tank, solar pump-station, controller) range from £1,000 for small flat plate systems to £5,000 for large evacuated tube systems (including VAT). Trade prices for flat plate collectors are between £150 and £250 per m2 (gross area) and for evacuated tubes, between £300 and £350 per m2 (gross area). VAT in the UK for solar thermal collectors is 20 %, although the VAT rate on installation, repair and maintenance of renewable source heating systems is 5 % (reduced rate for energy-saving products).

An installed domestic solar hot water system in the UK costs in the region of £3,500 to £7,000, including VAT, with the costs dependent on the type of system, roof access and location of hot water cylinder relative to the solar collectors. Typical payback periods for solar thermal systems in the UK are 10 to 15 years (STA).

In 2017, the average UK domestic consumer will have paid £619 for their electricity and £630 for gas (total £1,249) (BEIS, Annual domestic energy bills).

Status of the Market for Solar Buildings


Solar technologies for buildings beside solar thermal water heating that are recognised in the UK include solar PV, Passive Solar (i.e. designing for solar gain through windows etc.) and Transpired Solar Collectors (primarily for pre-heating of ventilation air). The concept of Passive Houses is recognised in the UK (and receives significant media coverage) but the concept of Solar Buildings is not one that is generally recognised.

Solar cooling is not currently used to any material extent in the UK.

Market Size and Trends

There are estimated to be around 1,000 buildings built (or under construction) to Passive House standard in the UK. Approximately 14,000 m2 of Transpired Solar Collectors have been installed in the UK to date.

Main Market Drivers

As previously stated, the concept of Solar Buildings is not widely recognised and, aside from some interest in the Passive House concept, there is little evident interest in Solar Buildings in the UK currently. Barriers to the Solar Buildings market in the UK include low awareness, the abandonment of the UK’s zero carbon homes policy, the resistance of the construction sector to significant change and the relatively low costs of conventional fuels.


Please refer to the response in relation to the Solar Thermal Systems market.


A 2015 study by the Passivhaus Trust (sponsored by AECOM) found that the average capital cost of a Passivhaus building in the UK was £1,800 /m2 - £1,850 /m2 (gross internal floor area and normalised to 2014 prices), which is a 15-20 % uplift from a building designed to the Code for Sustainable Homes (CFSH) Level 4 standard.

Other Key Topics

Notwithstanding the current lack of awareness of the Solar Buildings concept in the UK, the significant support for R&D in the UK provides opportunities for the development of technologies that can increase the feasibility of Solar Buildings (see section on R&D Activities).

R&D Activities

R&D Programmes

The UK Government has set out an industrial strategy with the objective of improving "living standards and economic growth by increasing productivity and driving growth across the whole country". Part of this modern industrial strategy is to deliver "affordable energy and clean growth" and "secure the economic benefits of the transition to a low-carbon economy" (HM Government, Building our Industrial Strategy Green Paper, 2017).

There is no dedicated national R&D programme for solar thermal, however, solar thermal projects (academic, industrial or collaborative) can bid into a number of funding competitions run by one of the Research Council, the Department for Business, Energy & Industrial Strategy (BEIS) or Innovate UK. The main competitions for organisations interested in solar thermal innovation are:

  • Energy Entrepreneurs Fund (EEF) – Run by BEIS, the EEF is a "competitive funding scheme to support the development and demonstration of state of the art technologies, products and processes in the areas of energy efficiency, power generation, and heat and electricity storage". £9 million was made available for the Phase 5 of the EEF and £10 million was available for projects in Phase 6.
  • Low Carbon Heating Technology Innovation Fund – In late 2017, BEIS launched a £10 million low carbon heating technology innovation competition to develop technologies that reduce the carbon emissions associated with providing heat and hot water to UK buildings.
  • Energy Catalyst - The Energy Catalyst was established by Innovate UK, the Engineering and Physical Sciences Research Council (EPSRC) and the Department of Energy and Climate Change (DECC) to accelerate innovation in the energy sector. "The aim of the Energy Catalyst competition is to support highly innovative, market-focused energy solutions in any technology or sector or international market" and in Round 5 of the Energy Catalyst, £13 million is allocated "to address the global need for clean, affordable and secure energy".

R&D Infrastructure

Institution Type Research Areas Involvement Website
BRE National Solar Centre Independent third-party approvals organisation Consultancy, research, testing, standards, training and products related to Solar Thermal and PV
Built Environment Research Institute Academic (Ulster University) Solar thermal, energy storage, zero carbon buildings Task 42
Centre for Efficient and Renewable Energy in Buildings (CEREB) Academic (London South Bank University) Solar PV, heat Pumps, lighting, CHP Task 58
Centre for Environment and Sustainability (CES) Academic (University of Surrey) Life cycle assessment, policy
Clean Energy Processes Laboratory Academic (Imperial College London) Solar cooling, high temperature collectors, organic Rankine cycle
CREST Academic (Loughborough University) Sustainable energy technologies
Energy Systems Catapult Industry, academia and Government consortium Transitions pathways to future energy systems
Energy Technologies Institute (ETI) Industry, academia and Government consortium Energy strategy and policy
Environmental Change Institute (ECI) Academic (University of Oxford) Policy, low carbon futures
Institute of Building Technology & Institute of Sustainable Energy Academic (The University of Nottingham) Solar thermal, heat pumps, heat storage, combined heat and power, desiccant cooling
i-STUTE Academic and industrial consortium Storage, transformation and upgrading of thermal energy
LIA Laboratory Independent test laboratory Lighting
Precision Engineering Institute Academic (Cranfield University) Concentrating Solar Power (CSP) plants
SPECIFIC Academic (Swansea University) and industrial consortium Building-integrated solar thermal and photovoltaics, thermal energy storage
The Pulham Group Academic (Edinburgh University) Compact heat storage
UK Energy Research Centre (UKERC) Academia and Government consortium (based at Imperial College London) Whole system energy modelling and policy
London South Bank University Academic (School of The Built Environment and Architecture) Heat Pumps, Solar Cooling, District Heating
Nottingham Trent University Academic (Smart Heat Networks Group) District Heating

Actual Innovations

Collectors Naked Energy has developed a vacuum tube solar thermal collector with PV cells as the absorber and Energy Transitions has developed Steel Zero, a Low-emissivity Transpired Solar Collector (Low-e TSC).

Compact Heat StorageSunamp has released a compact heat store (based on salt hydrates) for residential water heating and CREST (Loughborough University) is actively developing a range of new compact heat storage materials.

Buildings Viridian Solar has recently completed, alongside Melius Homes and Nottingham City Homes, the first Energiesprong refurbishment project outside the Netherlands. Energiesprong is an innovative refurbishment process in which a house is retrofitted to net zero energy in under a week.

Solar CoolingAES Solar is working on the EU Heat4Cool project which is investigating the integration of solar thermal with adsorption heat pumps and Solar Polar is working on an Energy Entrepreneurs Fund project to test a low cost solar thermal diffusion absorption refrigeration system in India.

Support Framework


The 2008 Climate Change Act established a legally-binding target to reduce the UK's net greenhouse gas (GHG) emissions to 80% of 1990 levels by 2050. In order to monitor progress against this target, the Government sets a series of five-year carbon emission targets (carbon budgets). The Department for Business, Energy and Industrial Strategy (BEIS) projections show that, given current Government policies, the UK is on target to achieve its emission reduction targets up to 2022 (the third carbon budget). Post-2022 (fourth and fifth carbon budgets), further Government measures are needed to achieve the required decarbonisation targets. The UK recently announced their intention to seek the Committee on Climate Change's advice on the implications of the Paris Agreement for the UK's long-term emissions reduction targets, after the release of the IPCC Special Report.

For the UK, one of the biggest challenges is "decarbonising the heating sector" (National Grid, Future Energy Scenarios 2016). Although emissions from the electricity supply sector have fallen significantly in recent years and are projected to fall further in the future, emissions from the domestic residential sector are projected to rise, with natural gas used for cooking and heating projected to rise by 17 % (from 2016 to 2035) (BEIS Updated energy and emissions projections: 2016).

Government Agencies Responsible for Solar Thermal, for Solar Building Activities

The UK Government Ministerial departments that have responsibilities related to solar thermal are:

  • Department for Business, Energy & Industrial Strategy (BEIS) – responsible for developing the UK's industrial strategy, energy statistics in the form of the Digest of United Kingdom Energy Statistics (DUKES) and works with Innovate UK and the Research Councils, see section on R&D Activities for further information.  Before July 2016 the responsibility for solar thermal lay with the Department for Energy and Climate Change (DECC).
  • Ministry for Housing, Communities and Local Government (MHCLG) – Works with the Building Regulations Advisory Committee to deliver the Building (domestic and non-domestic) Regulations (the principal document in relation to solar thermal is: Conservation of fuel and power: Approved Document L).

The UK Government non-ministerial departments that have responsibilities related to solar thermal are:

Industry organisations that have responsibilities related to solar thermal are:

Most Important Public Support Measure(s) for Solar Thermal and for Solar Buildings

The main policy incentive for installing solar thermal is the Renewable Heat Incentive (RHI) which has been in operation since April 2014 and has its budget set out until 2020/21. For solar thermal, the RHI provides around 20 p of subsidy for every kWh of renewable heat for a household's hot water for a period of 7 years. For business, the non-domestic RHI tariff is around 10 p/kWh over a 20-year period. Only solar thermal systems used for domestic hot water are eligible; this is not the case for biomass boilers or heat pumps where space heating installations are eligible for payments (

Information Resources

National Solar Associations (industry and non-industry)

The solar thermal industry represented by:

  • The Solar Trade Association (STA) - The STA was founded in 1978 and is a not-for-profit membership association that works to promote the benefits of solar energy (solar thermal and solar power). Chris Hewett is the CEO and Patrick Davis (Cool-Sky Ltd) is the chair of the STA Solar Thermal Working Group.

Multi-technology associations which include solar thermal are:

  • Renewable Energy Association (REA) - The REA is a not-for-profit trade association founded in 2001 and their mission is to "grow the renewable energy economy". The REA has over 700 companies as members and the REA solar group is UK Solar.
  • Sustainable Energy Association (SEA) - The SEA is an industry association focused on building-level technologies that can contribute to a low carbon, secure UK energy system.

Single technology associations that are related to the solar heating and cooling sector are:

  • British Photovoltaic Association (BPVA) - The BPVA is the trade association for the UK solar photovoltaic industry and its aim is to "ensure that solar photovoltaic energy is established as the leading renewable energy source in the UK and to promote UK solar internationally".
  • Heat Pump Association (HPA) - The HPA is the trade association for manufacturers and distributors of heat pumps in the UK.
  • Lighting Industry Association (LIA) - The LIA "is Europe's largest Trade Association for lighting equipment professionals".

National Associations on Green/Solar/Sustainable Buildings

Associations and organisations that undertake work in sustainable buildings are:

Not-for-profit organisations that advise on solar, energy efficiency and/or sustainable buildings are:

Organisations that advise on the wider energy strategy are:

  • Energy Technologies Institute (ETI) – Set up following the 2006 budget to "accelerate the development, demonstration and eventual commercial deployment of a focused portfolio of energy technologies, which will increase energy efficiency, reduce greenhouse gas emissions and help achieve energy and climate change goals".
  • UK Energy Research Centre (UKERC) – Academic consortium focusing on sustainable future energy systems.

Most Important Media for Solar Thermal and Solar Buildings

News on renewable energy related Parliamentary business (new legislation, committee meetings) can be found at and commentary on environmental legislation in "transform", the magazine of Institute of Environmental Management & Assessment (IEMA).

Online daily news on the solar energy industry can be found at the Solar Power Portal and commentary on commercial solar energy issues at the Solar Blogger which is written by Stuart Elmes, the former chair of the STA's Solar Thermal Working Group. General climate change policy news and analysis can be found on Carbon Brief.

News related to solar buildings can be found in construction focused journals, such as BuildingCIBSE Journal, Modern Building Services and the RIBA Journal, the official publication of the Royal Institute of British Architects (RIBA).