Solar Power Diverters

Solar power diverters help maximise self-consumption, cut gas or electricity bills, and reduce reliance on the grid by redirecting surplus solar power into heating hot water rather than exporting it.

Solar panels have become mainstream in the UK. Government data shows 19.1 GW of solar capacity in the UK across over 1.8 million installations at the end of July 2025.

Most of the installations are domestic, and they usually generate more power than is consumed during the day.

Households export surplus electricity at SEG rates, which average much lower than the cost of grid energy and fall below the household value of direct consumption.

Solar power diverters help fix this mismatch intelligently, redirecting excess solar power to the water heater and turning low-value exports into stored heat.

But what are solar power diverters, how do they work, and are they worth installing?

Key Takeaways:

Solar diverters turn excess PV electricity into heat for your hot water cylinder, maximising value while saving on energy bills.
In practice, better self-use of solar (via diverters) beats exporting since importing prices are usually higher.
A solar power diverter can add around £800 to your installation costs.
Wired diverters are more reliable but more complex to install, while wireless models are more straightforward to retrofit and often offer smart features.
Diverters can last up to 12 years or more, often matching or exceeding the lifespan of immersion heaters.

What Is a Solar Power Diverter?

A solar power diverter is a small electronic device connected to your solar PV system and immersion heater or other resistive heating devices like storage heaters.

It constantly monitors household solar generation and electricity demand.

If your solar panels produce more power than your home uses, the diverter redirects that surplus to your hot water cylinder via the immersion heater.
If demand rises again, like when you turn on the kettle, the diverter stops diverting and prioritises the household.

Instead of exporting low-value surplus electricity to the grid, you store it as hot water for free.

Using the energy your panels produce instead of exporting makes more sense because you’d typically buy electricity for more than twice the amount you’ll get through the Smart Export Guarantee.

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Diverters provide a simple yet highly effective way to automate energy use and help you maximise your solar investment.

How Do Solar Diverters Work?

Monitoring Generation

A solar diverter starts by tracking how much electricity your panels produce compared to what your home uses.

A small clamp sensor is fitted to the incoming supply cable, continuously measuring whether you’re drawing power from the grid or exporting back to it.

Detecting Surplus

When your solar generation exceeds household demand, like when your panels produce 2 kW while your home only uses 1 kW, the diverter recognises that 1 kW of surplus is being exported to the grid.

Redirecting to Hot Water

Rather than letting that spare electricity go, the diverter automatically diverts it to your immersion heater.

This energy heats water in your hot water cylinder, storing the surplus as useful thermal energy instead of sending it away.

Dynamic Control

Modern diverters don’t just work in big chunks of power. They can modulate in tiny steps, often down to 50 watts.

That means even small trickles of spare electricity can be captured and used.

In effect, diverters allow households to turn spare solar into free hot water, reducing reliance on gas or grid electricity. The process is seamless, automatic, and doesn’t require user input after installation.

What are the Benefits of Solar Power Diverters?

Solar diverters deliver tangible savings and environmental benefits:

Cost-saving hot water: Instead of exporting surplus solar at low SEG rates, your electricity goes straight into heating water, offsetting the need to buy gas or electricity later.
Reduced boiler wear: Relying on diverted energy to heat water means your boiler runs less frequently, potentially extending its lifespan.
Eco-friendly energy use: Every kWh used directly heats your water rather than feeding into the grid and incurring losses, reducing household carbon.
Low maintenance: These are plug-and-play solid-state devices once professionally installed.

When aligned with real-world solar usage and household demand, diverters offer excellent return on investment and energy efficiency.

What are the Limitations and Drawbacks?

Solar diverters aren’t perfect and include limitations like:

Needs a hot water cylinder: Homes with combi boilers and no storage tank can’t benefit from diverters.
Hot water demand dependent: The returned savings won’t justify the cost if your household uses minimal hot water.
SEG may pay more: In rare cases where export rates exceed the value of grid hot-water electricity, exporting may be more profitable.
Seasonal variation: Solar production peaks in summer, whereas hot water usage may be lower, saving more in summer and less in winter.

Understanding these factors helps you evaluate whether a diverter is the right choice.

Solar Power Diverters Benefits and Limitations Comparison:

Benefits	Limitations
Maximises self-consumption	Requires a hot water cylinder
Reduces energy bills	Savings depend on demand
Protects your boiler’s lifespan	Export tariffs trade-off
Low-cost upgrade	Seasonal variation
Low maintenance	Limited scope

How Do Wired and Wireless Diverters Differ?

Wired Diverters connect directly between your consumer unit and your immersion heater. They’re generally reliable, cheaper and ideal for fixed systems but require professional wiring.

Wireless Diverters use a clip-on current sensor on the main supply cable and send a radio signal to the diversion unit.

This simplifies installation, especially for retrofit projects where running new wiring is difficult. Some wireless units also offer app control and monitoring.

The right choice depends on your home’s wiring, ability to access existing wiring paths, and preference for smart monitoring features.

How Much Do Solar Power Diverters Cost?

According to the Energy Saving Trust, a solar diverter installation could add around £800 to your installation costs. This can cover the cost of the diverter unit itself and the labour costs.

Installation takes around 2–3 hours. It involves mounting the unit, attaching a sensor to your mains feed, and connecting to the immersion heater circuit.

Most installers recommend pairing diverters with a well-insulated hot water cylinder to store the energy effectively.

What are the Expected Savings?

The savings from a solar power diverter depend on how much surplus solar electricity your system produces and what energy source you usually use to heat water.

The Energy Saving Trust notes that households exporting surplus solar under the SEG typically receive around 12p for every unit.

In contrast, importing electricity from the grid costs around 25.73p per kWh under the July–September 2025 price cap.

Every kWh you divert to your immersion heater instead of exporting has a potential added value of 13p per kWh.

Are Solar Power Diverters Worth It?

Whether a solar power diverter is worth it depends on your home setup and energy use.

They are best suited to households with a hot water cylinder, high daytime solar exports, and regular hot water demand.

For these homes, diverters turn low-value SEG exports into hot water worth much more, giving predictable savings every year with virtually no maintenance.

They can also reduce wear on boilers, extending system life and adding to long-term value.

For all-electric homes, diverters are often a no-brainer, with paybacks close to two years thanks to high avoided electricity costs. Savings can be modest for homes with gas boilers, since gas is cheaper per kWh than electricity.

Still, even here, diverters provide a reliable way to boost the usefulness of your solar system, particularly as energy prices remain volatile.

However, diverters are not suitable for everyone. If you have a combi boiler with no hot water cylinder, or if you’re on a high SEG export tariff, exporting may make more financial sense.

However, for most typical UK households with a tank, solar diverters are a low-cost, low-maintenance upgrade that makes solar PV systems more effective and future-proof.

Final Thoughts

Solar power diverters are an efficient, low-cost way to boost your solar return, especially if you have a hot water cylinder and regular demand for heating.

Installing a diverter is a smart, proven move that delivers direct efficiency benefits and helps your solar PV system work harder and save more energy money.

FAQs on Solar Power Diverters

How Long Do Solar Diverters Last?

Solar diverters are solid-state electronic devices with no moving parts, allowing them to last a long time.

According to the Energy Saving Trust, you’ll need to replace your diverter after around 12 years.

Their lifespan usually matches or exceeds that of immersion heaters, making them a durable add-on to a solar PV system.

Do I Still Get Paid for Export with a Solar Diverter?

Yes. A solar diverter only redirects surplus electricity if your immersion heater can accept it.

Once your hot water tank is up to temperature, any additional surplus is exported to the grid as usual, and you still receive your SEG payments. This means you benefit from free hot water and export payments when you have excess solar.

Is a Solar Diverter Worth Installing?

Yes. If you have a hot water cylinder and a solar PV system, a diverter is a cost-effective upgrade that maximises the value of your electricity generation, with minimal maintenance.

For electric-heated homes, payback can be just a couple of years. It’s less suitable for homes without tanks or where export tariffs are unusually high.

References

GOV.UK – Solar photovoltaics deployment
Energy Saving Trust – Solar panels