How to buy solar panels Buying advice for solar water heating

Solar hot water heating panel

Solar water heating systems qualify for the Renewable Heat Incentive

Read on to find out what you need to know about buying solar water heating panels. We'll show you the sales tactics you need to watch out for, plus how to get a reputable installer.

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 one square metre of collector 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 collector (such as flat-plate solar water heating panels), you'll need to cover a larger area than if you use a more efficient collector (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 and posed 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.


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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 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
  • 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.

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

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. Which? members can find solar panel installers recommended by other members on Which? Local, or search for a certified installer on the Microgeneration Certification Scheme website.

Not yet a Which? member? You can trial Which? for a £1 to get instant access to all of our online reviews.

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.

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