In the UK, it’s thought that as much as 85% of homes are powered by gas. However, gas doesn’t fit in with the electrification of our energy systems.
The previous government had aims to phase out 80% of gas boilers by 2035. Although the new government hasn’t stood by this (instead they want to focus on incentivising heat pump installations), it’s clear that gas is not part of the long-term plan.
Heat pumps are fantastic, but they are a new type of system completely to a gas boiler. A much simpler shift for homeowners looking to wean off gas is an electric boiler.
When paired with solar panels, electric boilers can be a super-sustainable system.
However, there’s a little more to it than this. This article will look at how solar panels and electric boilers can work together, the advantages of this and the potential downsides.
What is an electric boiler?
An electric boiler works similarly to a traditional gas boiler – the major difference is that it runs off electricity rather than burning gas.
With electric boilers, you can get those that provide heat only or you can get electric combi boilers, which look after your heating and hot water needs. Combi boilers are the more preferred choice – in 2023, 77% of new boilers sold were combi boilers.
These systems connect to your central heating to warm radiators and provide hot water to taps and showers on demand. An electric boiler essentially works like a large non-boiling kettle, passing an electric current through a heating element to warm the water. A traditional boiler on the other hand burns gas each time you want to heat your home or get hot water.
Electric boilers can vary widely in their power requirements. They can range from 3kW for small space to upwards of 30kW for larger homes.
Good things to know about electric boilers
There are a number of benefits to electric boilers:
- Simplified installation – With fewer moving parts than gas boilers, electric models don’t require a flue or condensate pipe
- Low maintenance – Annual servicing isn’t necessary, reducing ongoing costs
- High efficiency – Electric combi boilers have a 99-100% efficiency rating
- Quiet operation – These systems run much more quietly than gas boilers
- Safety – No risk of carbon monoxide leaks
- Space saving – Electric boilers are much more compact than gas boilers
Downsides of electric boilers
Whilst electric boilers offer several advantages over gas boilers, it’s important to consider their limitations too:
- Limited heating capacity – Electric boilers have lower maximum outputs compared to gas boilers. This means they may struggle to meet the heating and hot water demands of larger homes, particularly those with more than 10 radiators.
- High running costs – Due to the higher cost of electricity compared to gas (mains electricity is four times higher!), electric boilers can be expensive to run if relying solely on grid power.
- Shorter lifespan – Electric boilers often have a shorter lifespan than gas boilers, with standard warranties ranging from just 2-5 years.
- Potential need for electrical system upgrades – Some homes may require upgrades to their electrical system to accommodate an electric boiler, adding to the installation cost.
Some of these downsides can be negated through the pairing of solar panels to your system. Let’s take a look at how solar panels and electric boilers can work together.
How solar panels and electric boilers can work together
The good news is that solar panels and electric boilers are entirely compatible. In fact, they can work together without any trouble at all to create a more sustainable and cost-effective home heating system.
Here’s how it works:
- Solar panels usually installed on a home’s roof generate DC electricity from sunlight.
- The solar inverter converts this DC electricity to AC, which is the same as mains electricity, and the type that can be used in your home.
- This solar-generated electricity can then power your electric boiler, along with other household appliances.
As you can see, there isn’t a direct link between solar panels and an electric boiler. They are two separate systems that work independently.
When there’s not enough solar power being generated – for example at night or on very cloudy days – your boiler will automatically draw power from the grid. The boiler itself doesn’t differentiate between solar-generated and grid electricity, it just uses whatever power is available.
It’s worth a quick mention for solar thermal panels. These can provide more direct hot water. Differing from standard solar panels, thermal panels that contain fluid which is heated up from the sun. This heated fluid then travels through pipework to your hot water cylinder, where it heats up the cold water from your mains. Whether or not an electric boiler is compatible with solar thermal depends on the manufacturer.
Benefits of pairing solar panels with electric boilers
Combining solar panels with an electric boiler offers a number of advantages for you and your home.
- Reduced energy costs – The biggest benefit is reduced energy costs. Electric boilers do come with high running costs. However, pairing up your electric boiler with solar panels means you can use the free electricity you’re generating during the daylight hours to run, or partially run, your boiler. We’ll take a closer look at running costs shortly.
- Lower carbon footprint – By using renewable solar energy, you’re greatly reducing your reliance on fossil fuels (mainly gas) and decreasing your home’s carbon emissions.
- Protection against rising energy prices – Generating your own electricity gives you a buffer against future increases in energy costs.
- Increased energy independence – With a solar-plus-electric boiler system, you’re less reliant on the national grid to provide gas for your heating and hot water needs.
Solar panels bring other benefits too, including the potential to increase your home’s value by as much as 14%. With a large enough solar array, you can run most of your household energy needs from self-generated electricity.
Running costs of electric boilers
An electric combi boiler generally costs somewhere between £2,000-£3,000, with installation bringing the total to around £3,000-£4,000 for a 3-bedroom house. This is roughly inline with a traditional gas boiler.
The running costs, however, can be much higher with an electric boiler – especially if you’re relying solely on grid electricity.
For example, let’s say you have a 12kW electric boiler that you use for an average of 5 hours a day across the year. The unit price of electricity is around 21.51p/kWh, meaning it would cost you about £12.90 per day (plus standing charge). Altogether your annual electricity bill just for an electric boiler would be £4,880.
This is where solar panels can make a significant difference. The integration of solar panels into your energy mix can reduce your running costs.
Whilst a standard solar system might not completely power your electric boiler all year round, thanks to seasonal variations and greater usage in the winter, even a small 3kW solar system would save you hundreds of pounds annually on your heating costs.
Challenges of pairing electric boilers and solar panel pairing
Although combining solar panels with electric boilers offers a number of benefits, there are limitations and challenges of this setup which are worth knowing about.
The primary challenge in pairing solar panels with electric boilers is the misalignment between energy production and usage. Most households tend to use hot water and heating in the mornings and evenings, while solar panels generate the bulk of their energy outside these hours. This timing mismatch is particularly pronounced during the UK’s short winter days, when solar energy production is at its lowest and heating demands are highest.
Seasonal variations further complicate this issue. Solar panel output fluctuates significantly between summer and winter, affecting the boiler’s reliance on grid electricity during colder months when heating demand peaks. This means that even with a solar panel system, you may still need to rely heavily on grid electricity during winter, potentially reducing the overall benefits of the system.
Determining the right number of solar panels to power an electric boiler is also a complex task. It depends on various factors including the boiler’s power consumption, panel efficiency and average sunlight hours in your location. It’s important to note that even a large solar panel system is unlikely to completely power an electric boiler year-round. Night-time energy needs and seasonal variations in sunlight mean that some level of grid dependency will likely remain.
To effectively use solar energy for heating year-round, you may need to install additional equipment, such as a hot water cylinder to store heated water for later use and battery storage systems. Whilst this can help bridge the gap between energy production and usage, it also takes up space and increases initial costs. This additional requirement might negate the space-saving benefits of a compact combi boiler, which is often a key selling point for electric boilers.
Why battery storage can play an important role with electric boilers
To address some of these challenges, particularly the timing mismatch between solar generation and heating demand, battery storage can play a crucial role. A solar battery system allows you to store excess solar energy generated during the day for use in the evening or at night.
Adding a battery to your solar-plus-boiler system offers several advantages:
- Increased self-consumption of solar energy
- Reduced reliance on grid electricity
- More consistent energy supply for your boiler, even when the sun isn’t shining
While battery storage adds to the initial system cost, it can significantly enhance the overall efficiency and effectiveness of your solar and electric boiler setup, paying for itself in just a few years.
You can learn more about how solar battery storage works and also find information on calculating storage size for solar panels.
Are solar panels and an electric boiler right for your home?
Combining solar panels with an electric boiler can be an excellent solution for many homes, but it’s not suitable for every property.
The size of your property currently plays the biggest role in determining the suitability of this combination. Electric boilers are best suited to small homes and flats. This is because larger properties with numerous radiators may struggle to meet their heating demands efficiently with an electric boiler alone.
The suitability of your roof for solar panels is also a key factor. For solar panels to be effective, you need a roof with good sun exposure. Whilst south-facing roofs are ideal, east or west-facing roofs can also work well. The condition and structure of your roof will also play a part in determining whether solar panel installation is feasible and how many panels you can install.
Budget is, of course, a significant consideration. The initial investment to install both solar panels and an electric boiler will be over £10,000 for most homes. As an electric boiler uses energy rather than generates it, it’s not going to pay for itself. This is why it’s vital to weigh up the running costs and how much solar panels can help you reduce these by. This is further complicated if you use most of your energy in the mornings and evenings as it may be wise to think about battery storage.
As with any significant home energy decision, you should consult with professionals who can assess your specific circumstances. They can help determine whether a solar-plus-electric boiler system is right for your home and, if so, design a system that maximises efficiency and savings.
