How Much Can You Save with Plug-In Solar in the UK?

The UK government says plug-in solar can save households up to £110 per year. But what does that really mean for your home, and what do the actual numbers depend on?

In this post we break down exactly how much you can expect to save with a plug-in solar system in the UK, what affects those savings, and whether it is worth the investment.

What the government says

When the government announced plug-in solar in March 2026, it estimated savings of up to £110 per year for a typical household. This figure is based on an 800W system in average UK conditions.

It is a reasonable starting point but your actual savings depend on several factors including where you live, how your panels are mounted, and how much electricity you use during the day.

The real numbers: Thunder Storm kits

Here is what Thunder's systems can generate and save based on a south-facing vertical installation in London, which is how most customers mount their panels on fences, balcony railings and walls.

Thunder Storm 360W (2 panels) generates up to 270 kWh per year. At 27p/kWh, that is up to £70 per year in reduced electricity bills.

Thunder Storm 710W (4 panels) generates up to 530 kWh per year. At 27p/kWh, that is up to £140 per year in reduced electricity bills.

These figures are based on London irradiance levels for a south-facing vertical surface (~775 kWh/m2/year), with standard system losses accounted for. If you mount your panels at an angle using a tilt bracket rather than flat against a fence or wall, your output and savings will be higher.

What affects your savings?

Mounting angle. Panels mounted vertically on a fence or wall generate less than panels tilted at 30 to 40 degrees. Vertical mounting is the most common setup for compact solar kits, and our savings figures reflect this. If you use a tilt bracket to angle your panels, expect improved performance.

Orientation. South-facing panels generate the most electricity in the UK. South-east or south-west is still good. East or west facing will produce noticeably less. North-facing is not recommended.

Shading. Trees, neighbouring buildings, and other obstructions that cast shadows on your panels during daylight hours reduce output. Even partial shading on one panel can affect the whole system. Choose the sunniest spot available.

Your electricity tariff. The higher your electricity rate, the more each generated kWh is worth. At 27p/kWh, a 530 kWh system saves £140. If rates rise to 30p/kWh, the same system saves £159. Electricity prices in the UK have been volatile in recent years, which means the value of self-generated solar power is likely to increase over time.

Self-consumption. Plug-in solar is most effective when you use the electricity as it is generated. If you are at home during the day running appliances like a fridge, washing machine, laptop or TV, you will use more of what your panels produce. If the house is empty during peak sunlight hours, some of that generation goes unused unless you add a battery.

Season. UK solar generation peaks between April and September when daylight hours are longest. Expect roughly 70 to 80% of your annual generation during these months. Winter output is lower but panels still generate on bright days.

Location. Southern England receives more annual sunlight than Scotland or Northern England. Our figures are based on London, which averages around 775 kWh/m2/year on a south-facing vertical surface. Homes further south may see slightly better results. Homes further north will see lower output.

Payback period

The payback period depends on what you spend and what you save.

Storm 360W kit (£499): Saving up to £70 per year gives a payback period of roughly 7 years. With improved placement or rising electricity rates, this could shorten to 5 to 6 years.

Storm 710W kit (£649): Saving up to £140 per year gives a payback period of roughly 4 to 5 years. With a tilt bracket or higher tariff, this could come down to 3 to 4 years.

Storm 710W with installation (£649 + £399 = £1,048): At up to £140 per year, payback is around 7 to 8 years. Adding a battery and maximising self-consumption can improve this.

Solar panels typically last 25 years or more. After the payback period, everything your system generates is pure savings. A Storm 710W system could save over £2,500 across its remaining lifetime after paying for itself.

Can you increase your savings?

Mount at an angle. If your setup allows it, angling your panels at 30 to 40 degrees rather than mounting vertically can increase annual generation by 30 to 40%. This is the single biggest improvement you can make.

Add a battery. A compact battery like the Thunder Vault allows you to store daytime solar energy and use it in the evening when grid prices are highest. This increases your self-consumption rate, meaning less of your generated electricity goes to waste. On smart tariffs with time-of-use pricing, the savings from a battery can be significant.

Use appliances during the day. Run your washing machine, dishwasher and other high-consumption appliances during peak sunlight hours. This is free electricity that would otherwise come from the grid. Setting timers on appliances is an easy way to maximise this.

Combine with a smart tariff. Tariffs like Octopus Go or Octopus Flux offer cheaper overnight electricity. If you charge a battery overnight at low rates and use solar during the day, you can reduce your grid consumption dramatically.

Is plug-in solar worth it?

For most UK households with some outdoor space and a south-facing surface, yes.

Even at conservative estimates, a 710W system pays for itself within 5 years and continues saving money for 20 years or more after that. Rising electricity prices improve the return further.

The upfront cost is also much lower than traditional rooftop solar, which typically starts from £7,000 or more. Plug-in solar gives you a low-risk, low-commitment entry point to solar energy. And if regulations change later to allow direct socket connection, your Thunder system is already ready.

Start saving today

You do not need to wait for plug-in regulations to start generating. Thunder Storm kits are available now and can be installed under current UK regulations via a fused spur on a dedicated radial circuit.

Explore Thunder Storm kits or book a free assessment to find out how much you could save based on your specific home.

Frequently asked questions

How much can I save with plug-in solar per year?

A Thunder Storm 710W system in London can save up to £140 per year at current electricity rates, based on a typical south-facing vertical installation. A Storm 360W system can save up to £70 per year. Savings increase with angled mounting, higher electricity tariffs, and greater daytime energy usage.

Is plug-in solar worth the investment?

For most households, yes. A Thunder Storm 710W kit at £649 can pay for itself in 4 to 5 years and continue saving money for 20 years or more after that. Rising electricity prices improve the return further.

How long do plug-in solar panels last?

Solar panels typically have a lifespan of 25 years or more. The Hoymiles microinverter included with Thunder kits carries a manufacturer warranty. Performance gradually decreases over time but panels continue generating for decades.

Will I save more in summer or winter?

Most of your savings will come between April and September when daylight hours are longest. Expect roughly 70 to 80% of your annual generation during these months. Winter output is lower but panels still generate on bright days.

Does plug-in solar work on cloudy days?

Yes. Solar panels generate electricity from daylight, not direct sunshine. Output is lower on overcast days but modern panels still produce meaningful energy. The UK climate is more suitable for solar than most people assume.

Can I save more by adding a battery?

Yes. A battery stores surplus daytime energy for evening use, increasing the amount of solar electricity you actually consume. This is particularly effective when combined with time-of-use electricity tariffs that charge higher rates during peak evening hours.