Solar Flat Plate Collectors: the Pros and Cons

flat plate collectors

Solar hot water systems, including flat plate collectors, use sunlight to heat water. They can be combined with a regular boiler, system boiler or immersion heater to ensure that a property is warm and has enough hot water whatever the season or time of day.

Flat plate collectors are one type of solar hot water system. They come in the form of panels that can be fitted onto roofs, walls or frames. The collectors are quite thin but have a large surface area to absorb as much heat as possible.

On average, 30cm² of panel can generate a day’s worth of hot water for a typical household.

To help you decide whether you should get flat plate collectors for your property, we’ve come up with a list of their pros and cons.


Save money on your energy bill

As sunlight is free, installing flat plate collectors is a great way to save money on your yearly energy bill. If you have a gas heating system you could save £60 and if you have electric immersion heating you could save £75.

Earn money through the Renewable Heat Incentive

If your system is fitted by an MCS-registered installer, you could earn money for using solar power to heat water through the government’s Renewable Heat Incentive (RHI). A 2m² system, which is usual for a 2 person household, could earn you £200 per year. A 6m² system, suitable for a 6 person household, could earn you as much as £485!

Cut your carbon footprint

If you want to help the environment, installing flat plate collectors is a great thing to do. Solar power is a form of renewable energy. By using sunlight instead of non-renewable fuels, you’ll be doing your bit to reduce the use of fossil fuels and cut your carbon footprint.

Get hot water throughout the year

Although winter in the UK is chilly, this doesn’t mean it’s not sunny. So you should be able to get some hot water from your solar collectors throughout the year.


You’ll probably need a backup heater

Solar hot water systems can be very efficient. But as it’s not sunny all the time, you’ll probably need a backup heater. You can either combine your solar system with a regular or system boiler or install an immersion heater to boost your water temperature when needed.

Solar hot water systems aren’t compatible with combi boilers

Solar hot water systems need an external hot water cylinder. As combi boilers don’t have one, they’re not compatible with solar hot water systems. So if you have a combi boiler and want a solar hot water system, you’ll have to pay extra to change your boiler.

Flat plate collectors can be less efficient than other systems

Although flat plate collectors are generally very effective, they can be slightly less efficient than evacuated tube solar panels. They are also slightly less compact.


£3,000-£5,000 inc. installation

Installation time

1-2 days

Advantages and disadvantages
  • Save £65 per year compared with gas heating
  • Earn up to £2345 from the Renewable Heat Incentive (RHI)
  • Get hot water throughout the year
  • You’ll need a compatible hot water cylinder or boiler – combi boilers are not compatible
  • It could take you 10 years to see a return on your investment