Over 70% of the average household’s energy use goes into space and water heating, so a source of free hot water to use instead of commercial energy can make a dramatic financial saving. Solar Water Heating is the renewable technology of choice for most UK households as it offers a quicker payback (7-15 years for an average household) than Photovoltaics (20-30 years) and the advantage that there is already an established network of installers. More immediate financial impact on your energy budget can achieved through energy saving measures such as loft and cavity wall insulation that typically pay for themselves in 1- 3 years. See Home Energy Saving.
However solar water heating does require plumbing and heating expertise to size, install and balance effectively, not typically suitable for the DIYer. When choosing an installer look for companies with recognised plumbing and heating certification such as CORGI, IPHE or APHC and experience in installing solar systems.
Solar Water Heating uses the radiation from the sun to heat water in a panel often sited on the roof which in turn can supply that heat as hot water or to a central heating system. Unfortunately the demands on your central heating system are at their highest when the sun is weakest so a solar heating system will only contribute to part of your heating energy requirements.
The positive side to the strength of the sun in summer is that it is the peak demand for swimming pools, static caravans and holiday lets.
If the system has been sized correctly, it can provide at least 40-60% of all your hot water requirements throughout the year. The average domestic system reduces carbon dioxide emissions by around 400kg per year.
Solar Water Heating should not be confused with generating electricity from the sun or photovoltaics (PV) in which solar power is used to directly generate electricity which can be used in the home or fed into the National Grid. See the section Power from the Sun for information on and suppliers of this technology.
Solar panels should be sited on a south-facing pitched roof, free of shade, at an angle of between 20 and 50 degrees, or may be mounted on an angled frame on the ground or on a flat roof. The typical domestic installation requires 2 – 5 square metres of roof area and you may also need space to locate an additional water cylinder if required.
Solar Collectors – Flat Plate or Evacuated Tube?
Solar collectors are currently available in two types; Flat Plate Collectors and Evacuated Tube Collectors.
Evacuated tube collectors have evacuated tubes each with a liquid filled copper conductor inside. As the liquid heats up it rises to the top of the tube where the heat is transferred in a manifold to the water from the cylinder.
In flat plate collectors the water passes through the whole plate where it is heated before returning to the cylinder. Flat plate collectors can more easily be integrated into the roof fabric and tend to have a lower profile than evacuated tubes.
Each system has its advantages in terms of price, efficiency and aesthetics. In general, evacuated tube collectors are more efficient and more expensive. A qualified heating installer may supply both plate types but will be able to advise on the appropriate technology for your project.
Boilers & Hot Water Tanks
In recent years many domestic boilers have been changed over to the more efficient condensing boilers but these are often unsuitable for receiving feeds from solar panels so an additional tank or boiler replacement may be required. These boilers are designed to take cold mains-pressure water, and solar systems supply hot or warm water at a lower pressure.
More recent developments have overcome these obstacles with packages able to plug into these boilers without replacement. Check with your solar system supplier to see if your boiler or tank is suitable.
Unlike central heating, swimming pools are most frequently in use when the sun’s radiation is at its strongest so heating a swimming pool is an ideal solar heating application.
Passive Solar Air Heaters.
Used extensively in Scandinavia and now starting to become available in the UK, Passive Solar Air Heaters heat air rather than a liquid.
They take external air, warm it and blow it into a property, thereby providing a free-to-run form of warm air space heating, powered entirely by the sun. Because the air’s moisture content is normally very low when the sun shines, they also have a powerful dehumidifying effect, displacing internal moist air with warmed dry fresh air, whilst providing significant ventilation at the same time.
They should not be confused with Air Source Heating Systems that use a heat pump to transfer energy for use in hot water and central heating systems.
For now we have classified suppliers of this technology, most notably SolarVenti, in Solar Heating Panel Suppliers
In July 2006 the Housing Minister, Yvette Cooper announced that from next year, changes to planning laws will allow householders to convert garages, build extensions, install solar panels and wind turbines - as long as they do not impact on neighbours.
At the moment planning consent is required if the work exceeds the 15% rule or if the building is listed or in a conservation area, National Park, AONB etc. Your solar system supplier will have assisted other project applications for the relevant consents in your area and will be able to assist you.
The government's Planning Portal website gives guidance on planning for domestic renewable projects. A link to it can be found in Government Departments.
Grants are available locally and nationally to offset part of the £2000 - £5000 typical cost of a domestic solar heating system. Visit our Grants page for information and links to online application forms.
The government’s Low Carbon Buildings Programme will provide a grant of up to £400 for a new domestic solar heating system , (in Scotland the grant rate is 30% of the system price up to a maximum of £4,000), but before awarding a grant, as a householder, you must demonstrate that you are not wasting energy elsewhere in your home and have taken measures such as installing loft insulation, cavity wall insulation, low energy light bulbs and room thermostat/timer controls for your central heating. Visit our Home Energy Saving section for ideas and suppliers of these technologies.
Local grants are often also available. For example, in London the Solar for London programme provides discounts on solar heating components of up to £1500 provided that the installation is undertaken by an approved supplier. Your system installer will be able to advise of grants available in your area.
Commercial Solar Water Heating
Solar Hot Water & Heating Systems scale up commercially. The larger your requirement, the larger the area of solar panelling and storage required.
Some Solar Heating Installers are experienced in sizing and installing commercial-scale systems in schools, leisure facilities and commercial buildings.
Click here to contact Commercial Solar Heating Suppliers.
Under the Enhanced Capital Allowances (ECA) scheme, you can claim an ‘enhanced’ 100% capital allowance on qualifying investments in equipment in the first tax year.
Unsecured interest-free Energy-Efficiency loans of up to £100,000 (£200,000 in Northern Ireland) are available for SMEs through the Carbon Trust for when you replace or upgrade your existing equipment with a more energy-efficient version to fund projects such as lighting, boilers or insulation. A similar scheme in Scotland is managed by Loan Action Scotland.
What to do next
Contact one or more solar heating suppliers that work in your area. A professional Solar Heating System Installer will offer you a comprehensive service which will typically involve the following steps:
- 1. Assess the feasibility of your project
- 2. Conduct a site survey of your property
- 3. Discuss the options with you including your legal obligations such as Building Regs.
- 4. Issue a formal quote
- 5. Assist with any grant applications
- 6. Install your solar heating system
- 7. Invoice you for the work, and
- 8. Issue a warranty.
The simplest way to contact Solar Heating Installers in your area is to use our email contact service, click here to go to our Domestic Solar Heating Suppliers page or Commercial Solar Heating Suppliers page where you can browse solar heating suppliers’ websites, send an email to several suppliers simultaneously or email companies individually.
Useful Sources of Information:
Solar Trade Association www.greenenergy.org.uk/sta
The Construction Centre: Domestic Boilers
The Construction Centre: Condensing Boilers
The Construction Centre: Local Authority Planning Departments