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Solar water heating

Solar Water Heating Installation

By Sarah Ingrams

Article 4 of 4

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Solar Water Heating Installation

We reveal all you need to know about solar thermal panels – from whether you need planning permission to tricks to maximise their efficiency. 

Thinking of installing solar water heating? We tell you what you need to know before you buy solar water heating panels.

Installing solar thermal panels will generate free hot water. Find out how to make solar thermal panel installation hassle-free.

The best location for solar thermal panels

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 keep the panels away from shadows (trees, buildings, chimneys, etc).

Some panels require regular checks of the unit and connections, or a wipe of the panel glass with mild detergent. Your installer should leave written details of any maintenance checks you should carry out from time to time. Bear in mind how difficult this can be when panels are up on your roof.

Planning permission for solar thermal panels

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. 

Contact your council to see whether you need to apply for planning permission for your solar panels. You'll also find more information about planning permission on the Energy Saving Trust's website.

Installing solar water-heating systems

A solar water-heating system involves pipe work, a thermostat and a hot water cylinder. 

Some also have a drainback system to drain water from inside the solar panel when the pump is switched off.

You can add solar water-heating panels to most existing hot-water systems. Although, 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. This is because combi boilers are designed to take cold, mains-pressure water - solar water-heating systems supply warm, low-pressure water. Some new combi boilers accept pre-heated water, so check with the manufacturer. 

To find out which boilers are the most reliable, take a look at our boiler reviews

Maximising solar water-heating efficiency

Before you install solar water heating, try to reduce the amount of hot water you use. Check our water-saving shower heads advice to get you started.

Make the most from your solar hot-water system by following these tips:

  • Use as much hot water as possible from the solar-heated supply, rather than heating up in an appliance using electricity. For example, fit a mixer shower (rather than electric) and check whether any ‘hot-fill’ appliances (which could include your washing machine) can take water from your solar system.
  • Consider changing your behaviour to use more hot water in the evenings – in showers, baths and washing-up. This is when water will be hottest, as it's had most time to heat up.
  • Ensure your back-up system is set up to switch on at the right time. Before you installed solar water heating, it was probably set to give you a full tank of hot water in the morning. But if you don’t change it, your panels will have nothing to heat during the day.
  • Insulate your pipes and water tank to make your system more efficient.
  • Follow your installer’s advice on how to set the hot water controls to get the most from your system.

Interested in using solar panels to generate free electricity? See our buying advice for solar PV.