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Solar water heating

Buying Advice for Solar Water Heating

By Sarah Ingrams

Article 3 of 4

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Buying Advice for Solar Water Heating

Find out what you need to know about buying solar water heating panels. Discover the sales tactics you need to watch out for, as well as how to get a reputable installer.

Don't buy solar water heating panels until you've read the results of our investigation into solar water heating firms. Plus, watch our exclusive video. 

Buying a solar water system isn't cheap so, before you invest, you need to find out if solar water is right for your home and needs. 

Our expert advice will help you to make that decision.

Choosing a solar water-heating system

When choosing a solar water heating system, you'll need to consider four major factors:

  • your average hot water use
  • the area of south-facing roof available
  • your existing water heating system
  • your budget. 

You'll need roughly 1square metre of panel area per person in the household. Each metre of panel area will need between 30 and 60 litres of water-tank volume.

If you use a less-efficient panel (such as flat-plate solar water-heating panels), you'll need to cover a larger area than if you use a more efficient one, such as evacuated tubes. 

You'll also need to select system components – such as a hot water cylinder, controls and pipe work – and choose the location for your solar panels, considering shade, pipe runs, roof pitch and future access. 

Video: Which? investigation into solar water-heating sales

We went undercover in 2010 to investigate solar water-heating companies by posing as householders wanting to buy a system. In our probe, 10 out of 14 companies exaggerated the potential savings. 

Here's a clip from our undercover video of the Ideal Solar Energy salesman in action. Identities have been disguised to protect our researcher.

Solar water-heating sales tactics

Here are the key points from our investigation:

  • 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 that such a system would cut about 10% from our householder's annual gas bill; Ideal Solar Energy quoted savings of 50%; and Everest quoted a 43% cut. Everest also claimed that the homeowner would save £35,000 over 20 years – a huge exaggeration.
  • None of the 14 companies tested identified all of the important technical challenges before providing a quote. 
  • Key checks they missed included inspecting the roof from the ground, 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.

If you think you've been mis-sold solar panels, or want to find out more about your rights, see misled by a solar sales pitch.

Finding a good solar panel company — things to look out for

Our investigations showed some salespeople 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're given by salespeople 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. 

You can search for a certified installer on the Microgeneration Certification Scheme website.

Your solar water heating system must be installed by an MCS certified installer to be eligible for payments under the Renewable Heat Incentive (RHI). You must also own the system.

Which? Trusted Traders will help you find a trustworthy local solar panel installer

Solar water-heating installation

Before you install your solar panels, find out more about whether you need planning permission and how to make a system more efficient – see our guide to installing a solar water-heating system.