solar panel savings calculator UK

Want to get a more accurate savings estimate tailored to your home? You can get a customised free solar panel survey from one of our experts. 

en you generate your own energy. This price cap directly impacts your potential bill savings. Which is why we factor it into our solar savings estimate.

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What goes into a solar savings estimate?

To build your savings estimate, we look at six things: how much electricity your home uses each year, how much power one solar panel can generate in your location, how many panels your home needs to cover your electricity use, how much you save by using the power your panels generate, how much you can earn by exporting surplus energy to the grid, and the additional saving from installing a battery alongside your panels.

We've included worked examples throughout this guide so you can see exactly how the numbers come together.

How much electricity does a typical UK home use?

Your home's annual electricity consumption is the single biggest factor in your savings calculation. The more electricity you use, the more opportunity there is for solar to cover it.

From 1 July 2026, Ofgem updated its Typical Domestic Consumption Values (TDCVs) — the official benchmarks used across the energy industry to represent typical household energy use. The new medium electricity TDCV is 2,500 kWh per year, down from 2,700 kWh. This reflects the fact that UK homes are genuinely using less electricity than before, driven by more efficient appliances, better insulation, and lasting behavioural change since the energy crisis.

We use the Ofgem TDCV as our baseline for savings calculations. All figures in this guide are based on the updated 2,500 kWh medium TDCV, correct at 1 July 2026.

How much electricity does your home use?

If you don't know your home's exact annual electricity use, here are some typical figures based on Ofgem's updated TDCVs, correct at 1 July 2026. A one or two bedroom flat or small house typically uses around 1,700 kWh per year — that's the low TDCV. A medium home, which is the standard benchmark for most savings comparisons, uses 2,500 kWh per year. A larger home with higher energy use can reach 3,900 kWh or more at the high TDCV.

The best way to know your exact consumption is to check your last 12 months of electricity bills, or read your smart meter's annual usage figure.

How much power can one solar panel generate?

The output of a single solar panel depends on its wattage and how much usable sunlight it receives in your location. We install 440W panels as standard.

The kK factor: how location affects output

Rather than working from daily sunlight hours alone, we use what's called the kK factor — a location-specific figure that combines solar irradiance levels, roof angle, and roof orientation into a single number. The higher the kK factor, the more your panels can generate. Locations in the south of England have higher kK factors than northern Scotland, reflecting the greater annual solar irradiance available.

The kK factor feeds into the output calculation as follows: maximum annual output per panel equals panel wattage in kilowatts multiplied by the kK factor. For a 440W panel in the Southampton area, on a south-facing roof at 35 degrees, that gives 0.44kW multiplied by 1,021, which equals 449 kWh per year. This is the figure we use as our per-panel generation baseline for a typical well-positioned UK installation.

Roof angle and orientation

A south-facing roof at 30 to 40 degrees is ideal for solar in the UK. East and west-facing roofs still generate meaningful power, particularly if the angle is adjusted. Our local experts check your roof orientation during the free survey and use the correct kK factor for your specific property. If your roof faces east or west, your savings estimate will reflect the slightly lower generation — it doesn't rule out solar, it just gives you an accurate picture.

Roof shading

Shading from trees, chimneys, or nearby buildings can reduce output significantly. Even partial shading on one panel can affect the whole system if it shares an inverter. Our survey assesses shading as part of the site assessment. Our baseline calculations assume no shading — your personalised estimate will reflect your actual roof conditions.

How many solar panels does your home need?

Once you know your annual consumption and per-panel output, the calculation is straightforward. The number of panels you need equals your annual electricity use divided by the annual output per panel.

For a typical medium home using 2,500 kWh per year, with panels generating 449 kWh each, that's 2,500 divided by 449, which gives 5.57 — rounded up to 6 panels as a minimum.

In practice, we recommend a larger system to maximise self-sufficiency and export income. Our standard installation is 12 × 440W panels, which generates approximately 4,750 kWh per year — well above the 2,500 kWh TDCV, with the surplus available to store in a battery or export to the grid.

For smaller homes using around 1,700 kWh per year, a 4 to 6 panel system may be sufficient. For larger homes using 3,500 kWh or more, a 10 to 14 panel system gives better coverage. Your free survey will give you an exact recommendation based on your home's consumption and roof space.

How much do you save by using your own solar electricity?

Every unit of electricity your solar panels generate that you use directly at home is a unit you don't have to buy from the grid. The saving per unit is your electricity unit rate — currently 26.11p/kWh on OVO's Standard Variable Rate from 1 July 2026.

Our self-sufficiency basis

Our standard savings calculation is based on a 12-panel, 10 kWh battery system generating 4,750 kWh per year. With a 10 kWh battery, the system covers 75% of a typical household's electricity needs — that's 1,875 kWh of the 2,500 kWh Ofgem TDCV. The remaining 625 kWh is still drawn from the grid, costing £163.19 per year at 26.11p/kWh.

Without solar, the same household would pay £652.75 per year — that's 2,500 kWh multiplied by 26.11p. With solar, the annual electricity bill falls to £163.19. That's an annual bill saving of £489.56, a reduction of 75%.

How does self-sufficiency change with different system sizes?

A smaller system without a battery — say 6 panels — might cover 35 to 40% of a typical household's electricity needs, leaving the majority still drawn from the grid. A 12-panel system without a battery typically achieves around 50 to 55% self-sufficiency. Adding a 10 kWh battery pushes that to 75%, because it captures generation during the middle of the day and releases it in the evening when demand is highest. The battery is what makes the difference between a good saving and a great one.

How much can you earn from exporting surplus solar electricity?

Any electricity your panels generate that you don't use at home — and that isn't stored in your battery — is exported to the grid. Through the Smart Export Guarantee (SEG), you get paid for every unit you export.

OVO's SEG tariff rates

OVO offers four SEG tariff options. The standard SEG tariff pays 4p per kWh and is available to any home generating renewable energy, regardless of who supplies their electricity. The SEG Beyond Exclusive tariff pays 12p per kWh and is available to OVO electricity customers who meet the tariff criteria. The SEG Install Exclusive solar-only tariff pays 15p per kWh for OVO customers who have solar panels installed by OVO without a battery. The SEG Install Exclusive solar and battery tariff pays up to 20p per kWh for OVO customers who have both solar panels and a battery installed by OVO. All rates are correct at 1 July 2026.

How much can you earn?

Our standard 12-panel, 10 kWh battery system exports 2,875 kWh per year. At the Install Exclusive rate of 20p/kWh, that's 2,875 multiplied by 20p, which equals £575 per year in SEG income.

Combined with the £490 bill saving, the total annual benefit is £1,065 per year.

How does a solar battery increase your savings?

A battery stores surplus solar energy generated during the day so you can use it in the evening, when your panels aren't generating. This increases the proportion of your electricity needs met by solar and reduces how much you buy from the grid.

How battery size affects self-sufficiency

Without a battery, surplus solar electricity exports immediately to the grid. With a 10 kWh battery, the system can store enough to cover most evening and overnight demand for a typical household. This is how the system achieves 75% self-sufficiency against the 2,500 kWh Ofgem TDCV.

Battery capacity also affects how much you export. A larger battery means less export but more self-consumption. Since saving on your bill at 26.11p/kWh is worth considerably more per unit than the standard SEG export rate of 4p/kWh, maximising self-consumption is usually the better financial outcome. Only when you're on the Install Exclusive 20p SEG rate does the maths become closer — and at that rate, the combination of high self-consumption and strong export income delivers the best overall result.

Is a battery worth the extra cost?

A 10 kWh battery adds approximately £4,000 to £6,000 to the upfront cost of a solar installation. But it also increases the annual benefit significantly — from roughly £400 to £500 per year for solar only, up to £1,065 per year for solar and battery including SEG income. The additional saving means the battery typically pays for itself within the wider payback period of the overall system. OVO offers 0% finance on GivEnergy batteries, which means the additional monthly cost can be spread without interest.

Full worked example: a medium home in the UK

Here's the complete savings calculation for a typical medium UK home, using our confirmed figures correct at 1 July 2026.

The home: three bedroom semi-detached, south-facing roof at 35 degrees, Southampton area, annual electricity consumption of 2,500 kWh (Ofgem medium TDCV).

The system: 12 × 440W solar panels plus a 10 kWh battery, generating 4,750 kWh per year.

Annual bill without solar: 2,500 kWh × 26.11p = £652.75

Self-consumption: 75% of the 2,500 kWh TDCV = 1,875 kWh covered by solar. Remaining grid import: 625 kWh = £163.19.

Annual bill saving: £652.75 minus £163.19 = £489.56, a 75% reduction.

SEG export income: 2,875 kWh exported × 20p (Install Exclusive rate) = £575.

Total annual benefit: £489.56 + £575 = £1,065 per year.

Frequently asked questions

How is the solar savings calculation worked out?

We calculate savings by comparing what a typical household pays for electricity without solar against what they pay with solar, using Ofgem's medium TDCV as the consumption baseline. We then add SEG export income on top. All figures use OVO's Standard Variable Rate and are correct at 1 July 2026.

What is the Ofgem TDCV and why does it matter for solar savings?

TDCV stands for Typical Domestic Consumption Value. It is the official annual consumption benchmark set by Ofgem. From 1 July 2026, the medium electricity TDCV is 2,500 kWh per year. It matters because it is the baseline we use to calculate what a typical household spends on electricity without solar — and therefore how much solar can save.

How much can I save with solar panels in 2026?

Based on a 12-panel, 10 kWh battery system generating 4,750 kWh per year, a typical household can save £490 per year on their electricity bill — a 75% reduction — and earn up to £575 per year in SEG export income, for a total annual benefit of up to £1,065. Individual results will vary depending on system size, consumption, roof orientation, and location.

Does the savings calculation change if I use more or less electricity than the Ofgem average?

Yes. The Ofgem TDCV is a benchmark for a typical household. If you use more than 2,500 kWh per year, your actual saving in £ terms will be higher. If you use less, it may be lower. A free survey from OVO gives you a personalised estimate based on your actual consumption.

What SEG rate does OVO use in its savings calculations?

Our headline savings figure uses the SEG Install Exclusive rate of 20p/kWh, available to OVO customers who have both solar panels and a battery installed by OVO. If you don't have a battery, the Install Exclusive solar-only rate of 15p/kWh applies. The standard SEG rate is 4p/kWh for customers with any supplier. All rates correct at 1 July 2026.

Why do solar savings figures look different now compared to before July 2026?

From 1 July 2026, Ofgem reduced the medium electricity TDCV from 2,700 kWh to 2,500 kWh per year. This changes the baseline used to calculate typical household energy costs and solar savings. Any savings figures published before July 2026 used the old 2,700 kWh benchmark — the new figures reflect the updated Ofgem benchmark and OVO's current unit rate of 26.11p/kWh. The solar system performs exactly the same — only the measurement benchmark has changed.

Get a savings estimate for your home

Every home is different. System size, roof orientation, location, and your actual electricity use all affect your real-world savings. The best way to see what solar could save you is to get a free survey and personalised estimate from OVO's local team.

All savings figures are based on a 12 × 440W solar panel system with a 10 kWh battery, generating 4,750 kWh per year. Self-sufficiency of 75% is calculated against the Ofgem medium electricity TDCV of 2,500 kWh per year, correct at 1 July 2026. OVO Standard Variable Rate of 26.11p/kWh and standing charge of 57.19p/day, correct at 1 July 2026. SEG income calculated at 20p/kWh on 2,875 kWh exported annually under the SEG Install Exclusive tariff, available to OVO customers who have solar panels and a battery installed by OVO. Annual bill without solar: £652.75. Remaining grid import with solar: 625 kWh = £163.19 per year. Annual bill saving: £489.56. Total annual benefit including SEG income: £1,065 per year. Individual results will vary depending on system size, household consumption, roof orientation, location, and tariff.