How to buy solar panels How to buy solar water heating panels
Solar panels should be mounted on a south-facing section of your roof
Solar water heating costs and savings
Solar water heating panels typically cost between £3,000 and £5,000, and will potentially save you between £55 and £80 a year on water heating costs, with bigger savings to be made if you have an electric heating system.
Solar heating systems qualify for the Renewable Heat Premium Payment scheme which runs until 31 March 2013. This provides a grant of £300 towards the cost of installing a solar thermal system. More details are available from the Energy Saving Trust website. A more generous incentive is expected when the government will introduce the Renewable Heat Incentive scheme, which could be similar to the feed-in tariff scheme for solar PV and pay consumers for generating 'low carbon' heat.
We recommend that you first make sure your home is as energy-efficient as possible, then think about which types of renewable energy technology – including solar panels – might suit you. You can use the Energy Saving Trust's home energy generation selector tool to see which types of renewable energy might be appropriate for your home.
Which? investigation into solar water heating sales
Make sure you choose a reputable installer. In early 2010 we went undercover to investigate solar water heating companies and posed as householders wanting to buy a system. In our probe, 10 out of 14 companies exaggerated the potential savings.
Everest and Ideal Solar Energy potentially broke the law, using dodgy sales tactics and hugely overstating the potential benefits of installing a solar thermal system. An independent expert calculated such a system would cut about 10% from our householder's annual gas bill, but Ideal Solar Energy quoted savings of 50%, and Everest quoted a 43% cut. Everest also claimed the homeowner would save £35,000 over 20 years – a huge exaggeration.
Here's a clip from our undercover video of the Ideal Solar Energy salesman in action. Identities have been disguised to protect our researcher.
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Not one of the 14 companies tested identified all the important technical challenges before providing a quote. Key checks they missed included inspecting the roof from the ground, inspecting the existing gas boiler, the cold water tank in the loft and the hot water cylinder, and checking the water quality and whether the washing machine and dishwasher could use solar-heated water. Five gave a quote over the phone without even bothering to visit the property. Just one company, Southern Solar, was helpful and provided sensible advice.
Finding a good solar company - things to look out for
Our investigations showed some salesmen using dodgy sales tactics and exaggerating the financial savings that could be made, so we strongly recommend that you do your own research first. Then compare the estimates of costs and savings you are given by salesmen against other sources of advice.
There are many solar panel installers out there, so we recommend that you always collect a range of quotes to compare. Visit Which? Local to find recommended solar panel installers, or search for a certified installer on the Microgeneration Certification Scheme website.
Solar water heating panels can be added to most hot water systems
Choosing a location for your solar panel
For maximum efficiency, you need to put your solar panels on a south-facing roof at a 30-degree angle to the horizontal (up to 65 degrees will still work in the UK) and away from the shadows of trees, buildings or chimneys.
Some panels require regular checks of the unit and connections, or a wipe of the panel glass with mild detergent. Bear in mind how difficult this can be when panels are up on your roof.
Planning permission for solar panels
Contact your council to see whether you need to apply for planning permission for your solar panel. You won’t need planning permission for most domestic solar panels, as long as they respect certain size criteria, but exceptions apply for listed buildings, buildings in conservation areas and world heritage sites. The EST has more information on planning permission.
Installing solar panel systems
A solar water heating system involves pipe work, a thermostat and hot water cylinder.
You can add solar water heating panels to most existing hot water systems, though you'll usually need to add an additional cylinder for pre-heated water, or change your existing cylinder for one with a twin coil.
It’s difficult to use a solar water heating system with a combi boiler because these are designed to take cold mains-pressure water and solar water heating systems supply low-pressure warm water. Some new combi boilers accept pre-heated water, so check with the manufacturer.
Maximising efficiency
In October 2011, the Energy Saving Trust released the results of their field trials of 88 solar hot water systems. It found that proper installation, householders' behaviour and insulation of the pipes and water tank are all key in improving the performance of a solar hot water system, so you can save the most on your heating bills. System performances can be improved if the pumps and timers are set correctly. Also it found that in some houses, the lack of insulation on the hot water tank and the pipes led to lower performances because of losses.
The Energy Saving Trust also found that, generally, solar thermal systems worked well and 84% of the people who took part in the trial were either fairly or very happy with their system.
Replay our solar panels live Q&A
Our team of experts were inundated with questions from homeowners considering their solar options during our live Q&A, covering everything from energy savings and feed-in tariffs to installation, inverters and maintenance.
Missed it? You can rewind and replay all the action at Which.co.uk/solarlive.
- Find out how solar water-heating panels work
- Which? advice: pros and cons of solar water-heating
- Can you get £300 through the Renewable Heat Incentive Premium Payment?
