James Elston

James Elston

Published June 5, 2024

The short answer is yes – some combi boilers can be used with solar panels. In fact, it is highly recommended as it is a great way to lower your energy bills and reduce your carbon footprint. However, not all combi boilers can be paired with solar panels.

Homeowners and business owners can connect their boilers with either solar thermal panels or solar PV. Each of these systems has its merits; however, your energy requirements and lifestyle will determine which is best suited to your needs.

We will explore how these two systems can work together, the pros and cons, the costs, and what kind of systems are best suited to each other.

How Does A Combi Boiler Work With Solar Panels?

Electric combi boilers are connected to the home’s electrical supply system. Solar panels are connected to an inverter which powers the same supply system. The stored solar energy is converted into electricity and supplied to the boiler. For these systems to work together, additional components, such as a diverter valve, may be required.

It is important to remember that not all makes and models of combi boilers will be compatible with solar panels. Since only certain types of boilers are designed to accept pre-heated water, those without temperature-rated components will be unable to do this.

So, if you already have a combi boiler installed, you would need to check with a certified installer to ensure it is compatible. If you are shopping for a new combi boiler that can be paired with a solar panel system or are looking to install solar panels, Eco Happy can provide guidance.

Should you use a solar battery with your solar panels and combi boiler?

Using a solar battery with solar panels ensures you have access to solar energy even during hours when there is no direct sunlight. 

Solar batteries allow for a consistent supply of electricity. Without one, boilers still require an immersion heater to keep water hot if your power supply comes from solar panels. Alternatively, you will need to switch over to the national grid supply during these times to power your combi boiler. 

What Are The Advantages And Disadvantages Of Using A Combi Boiler With Solar Panels?

Weighing up these pros and cons will help you determine whether a combi boiler paired with solar panels will suit your home and heat requirements.


An electric combi boiler can have expensive running costs due to rising electricity prices. By using your solar panels in conjunction with your boiler, you can save a significant amount on your energy bills. The combined use is incredibly sustainable and lowers your carbon emissions.


There are a few drawbacks to using combi boilers and solar panels together. 

Firstly, your existing boiler may not have the necessary components to allow this hybrid system to work. 

Secondly, of all the boiler systems, combis are least often paired with solar panels. Therefore, this combination is still relatively new to many boiler installers. 

Which Solar Panels Are Better for Combi Boilers?

This depends on your needs and preferences. Both systems have advantages and disadvantages.

Solar Panel Type Advantages Disadvantages 
Solar PV systemCost-effective.Provides power for heating and other appliances.More versatile.Requires more roof space. May need immersion optimisers when combined with combi boilers. Annual maintenance is £150, which is more expensive than solar thermal systems.
Solar thermal systemProvides solar heating. Requires less roof space, as fewer panels are required to meet heating needs. Higher energy efficiency than solar PV. It can be used for water heating systems. Annual maintenance is around £75.Does not provide electricity for other appliances. Requires a hot water cylinder or thermal storage tank. Shorter lifespan than solar PV panels. May require more frequent maintenance.

The good news is you are not limited to just one type of system. You have the option of combining solar panels. This will allow you to run your combi boiler while lowering your energy bills to meet your heating and hot water requirements.

How Much Does It Cost To Install Solar Panels And A Combi Boiler?

The average overall cost for a new combi boiler and solar panel system is £6,500 – £10,500, without a solar battery. 

Solar panel installation cost

Various factors affect the overall costs of installing solar panels. You must consider roof space, energy needs, how many solar panels you need, the brand, and system size. The solar panel installation cost has been illustrated using a 1-2 bedroom flat or house using either 350W or 450W panels.

House SizeSystem SizeSolar Panel Cost Incl InstallationSolar Battery CostTotal Cost
1 Bedroom3 kWh£5,000 – £6,000£2,500 – £3,500£7,500 – £9,500
1-2 Bedrooms4 kWh£6,000 – £8,000£3,500 – £4,000£9,500 – £12,000

Combi boiler installation cost

The average cost of a combi boiler is £1,500 – £4,500, including the installation. Additional costs for components to allow it to be used with solar panels will increase the overall price.


Are all boilers compatible with solar panels?

Most modern, conventional, and biomass boilers are compatible with solar panels. Older gas and oil boilers may not be compatible due to their age and design. Conventional and system boilers are considered perfect for solar panel systems as they already have a hot water cylinder in place.

What percentage of existing combi boilers cannot work with solar panels?

Currently, around 45% of combi boilers are not designed to accept preheated water, which means they are not compatible with solar panels. If your boiler does accept pre heated water, it is important to find out about the maximum temperature of the water. Some combi boilers are not suited to accept water over a certain temperature. 

Who should connect your combi boiler to your solar panel system?

This connection should be done by a qualified and certified heating or electrical engineer.

What kind of appliances cannot be used with solar power?

It is recommended that appliances such as electrical ovens, stovetops and refrigerators are not run with solar power. These appliances use a lot of electricity and will likely use up your supply. If you do have a larger solar panel system, using these appliances is a possibility.


Using solar panels or solar heating systems with your combi boiler can be done, if the boiler design allows it. Since combis are more commonly found in smaller households, solar thermal systems may not be a possibility as additional space is needed for a hot water cylinder.

Solar PV panels are a more versatile and cost-effective option where combi boilers are concerned. If you would like to use solar panels with your combi boiler contact Eco Happy and we’ll advise you on the best way to make this happen.

James Elston

James Elston

Boiler Expert

James Elston is the top boiler replacement and heating expert at Eco Happy. He has over 20 years of experience in the industry, focusing on Gas Safe boiler installations and offering home-heating and energy-saving solutions to homeowners across the UK. From sourcing the most energy-efficient combi boiler to providing specialist heating advice, James ensures that Eco Happy maintains the highest standards and best customer service.

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