An electric combi boiler is the ideal choice for small and off-grid homes but the running costs often put many homeowners off having one installed.
To keep those running costs down, pair an electric boiler with a solar PV system and it will be powered by free renewable energy from the sun. Helping to keep your energy bills at an absolute minimum.
What is an electric combi boiler?
Electric boilers provide your home with heating and domestic hot water just like any other type of boiler. The only difference being that they use electricity to heat the water rather than gas or oil – in a very similar way to an electric kettle.
Unlike gas combi boilers, that provide instant hot water to taps, electric combi boilers include a hot water cylinder (either within the unit or installed elsewhere) that stores hot water before being sent to the taps.
Benefits of an electric boiler
For certain types of home, an electric boiler can offer many advantages but if you live in a larger property with a high demand for heating and hot water, then an electric boiler isn’t the best option. The many benefits of an electric boiler include:
- Cheaper to install than a gas or oil boiler
- Installation is flexible as they don’t need to be installed onto an outdoor wall
- Mains electricity is readily available whenever you need heating or hot water
- No risk of a carbon monoxide leak
- No need for an annual service
- Reduced maintenance costs as they have less moving parts that can develop a fault
- Take up much less space than other fuel types as there’s no need for a flue or condensate pipe
- Ideal solution for off-grid homes
In addition to the above benefits, it’s possible to run an electric boiler during the day at no expense with a solar PV system. By turning free renewable solar energy into electricity for your home, you’ll reduce your reliance on your energy supplier as well as your electricity bills as a result.
Electric boiler with solar PV
Rather than relying on an energy supplier and electricity from a power station that produces CO2 (unless you’re with a renewable energy supplier), enjoy free renewable energy from the sun.
Adding a solar battery to the system will allow you to continue using solar energy into the night when the solar panels aren’t generating any energy. Further reducing your reliance on your energy supplier.
Some solar batteries, such as the Tesla Powerwall 2.0, have an Uninterruptible Power Supply (UPS) which means they will continue to work even during a power cut. So, you’ll still have heating and hot water when the power’s out.
Electric boiler with solar thermal
Solar PV systems generate electricity that can be used to reduce the boiler’s running costs, while solar thermal uses energy from the sun to heat water, providing domestic hot water and solar central heating system.
The solar thermal panels, located on the roof, have a fluid within them that gets heated by the sun. This fluid then circulates down to the water tank and around a coil, heating up the water in the hot water tank.
An electric boiler being compatible with solar thermal is dependent on the manufacturer, so you’ll need to check with them directly but it’s possible with some of the bigger manufacturers.
| Manufacturer | Solar Thermal Compatibility |
| Heatrae Sadia | Solar-ready heating cylinders available |
| Thermaflow | Can be paired with solar thermal – recommend their own Thermaflow solar systems |
| Electric Heating Company | Possible but not recommended unless the solar thermal system is relatively large. |
| Elnur | Compatible with solar thermal panels |
Electric boiler running costs explained
When comparing electric boilers, you’ll notice that they all tend to be around the 99%-100% mark for efficiency – showing that very little heat is lost as they operate. Making them much more appealing than gas and oil boilers, which tend to reach a maximum efficiency of around 93%.
While they have this high efficiency, electric boilers come with an ErP rating of C or D, while gas and oil boilers will normally always have an A-rating, which can be confusing.
While the high efficiency percentage given to electric boilers isn’t untrue, electricity is seen as a ‘carbon intensive’ fuel due to the emissions created during the process of creating the electricity at the power station. Which, in turn, makes it more expensive to run when it reaches your home.
This is the case even if you’re with an energy supplier such as Shell Energy, who deliver 100% renewable energy, as all fuel types are given the same score across the board, no matter how they’re generated. This rating could drop as more energy suppliers adopt renewable energy.
As well as solar, it’s possible to counter the high running costs of electricity by turning to an Economy 7 or Economy 10 tariff, which offer cheaper rates during the night. That way, the electric boiler can heat water at a lower rate and keep it stored in the hot water cylinder for when you need it.
After the UK experienced its greenest winter in 2018-19, the National Grid believe all UK electricity production could be free of carbon emissions by 2025, which will only help the ErP rating of electric boilers.
Finding the right electric boiler for your home
Electric boilers are an ideal way for small and off-grid homes to gain access to heating and hot water. Due to the amount of water they can produce, electric boilers aren’t always recommended for larger homes with a higher demand for heating and hot water.
As a general rule of thumb you want a boiler with 1.5kW for every radiator around your home. So if you have 8 radiators, a 12kW electric boiler should be enough to heat them all up sufficiently.
When comparing electric boiler models, you’ll need to make sure that the unit is suitable for your electricity supply so take note of the following:
- Voltage of the unit – UK homes have an electricity supply of 230 volts, although some may have 250v;
- If your property has a single-phase or three-phase electricity supply.
If you’re unsure then an electrician will be able to provide the information you need.
Get free electric boiler quotes
Replacing a gas boiler with an electric boiler requires a Gas Safe registered engineer to remove the gas boiler and then install the electric boiler. For oil boilers an OFTEC engineer is needed. Once the electric boiler is in place, an electrician will be needed to make the final adjustments to the wiring. Your installer might be able to arrange this for you.
Depending on the installer carrying out the electric boiler installation, the price can vary greatly. For that reason, we highly recommend comparing quotes from multiple boiler installers before hiring one. The same goes for solar installers too if you’re interested in solar panels.
Using Boiler Guide, you can get free quotes from up to 3 heating engineers based in your local area. Simply complete an online form, providing details of the work and you’ll have your free no-obligation quotes in no time at all.
