See how much solar panels and a home battery could save you, and which sizes make sense for your home.
Your answers are kept on this device.
Sets how much sunshine your area gets.
It's on your annual statement. A typical UK home uses about 2,500 kWh.
A heat pump or electric heaters put much more of your use in winter, when there's least sun.
Power used while the sun is up comes straight from the panels.
Economy 7 and electric car tariffs are cheaper overnight, so a battery can charge up cheaply and power your home the next day.
The fixed daily charge on your bill. It's taken off before we work out how much electricity you use.
We've filled in the price cap for 1 October to 31 December 2026, which covers England, Scotland and Wales but not Northern Ireland. Your bill shows your actual prices.
What you're paid for solar you send to the grid. The best deals pay around 12p, but many suppliers pay nearer 4p.
Around 8p on electric car tariffs, and around 15p on Economy 7.
The battery charges from the grid in these hours.
This is part of the electricity you use a year, not on top of it. A car doing 8,000 miles a year takes about 2,500 kWh.
Your heating then already runs on the cheap rate, so a battery has less to save.
Panels on your roof, at the size we suggest from how much electricity you use, or one you pick yourself.
Add an array for each roof the panels go on. With one array you can leave the size blank for our suggestion.
Keeps the solar you can't use as it's made, and charges up cheaply overnight on the right tariff.
The suggested size is where each extra kWh stops adding much saving.
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Each extra kWh of battery saves less than the one before.
Where your electricity comes from, and the solar you export.
Hour by hour in June.
Hour by hour in December.
Saving a year for each solar and battery size. Select a cell to see it above.
These are estimates for a typical year, to help you compare options. Solar figures are based on PVGIS data (© European Union, JRC) for your region. Your household's use is modelled on a typical UK home. Real results depend on shading, the exact panels and your habits, so ask an installer to survey your home before you buy.
Disclaimer: These are indicative estimates, not an MCS performance estimate or a system design. They assume nothing shades the panels, typical-year sunshine for your region and a typical UK home's pattern of use, so your own saving could differ by 10% or more. Prices stay at what you enter, and panels and batteries fading with age, repairs and any limit on how much you can export are left out. Payback is the quote divided by the first year's saving. Most suppliers only pay for exports from an MCS-certified installation. Have a qualified installer survey your home before you buy. ProWorks gives no warranty as to accuracy or fitness for purpose and accepts no liability for any loss arising from use of these results.
It works through all 8,760 hours of a typical year. Each hour, the solar power goes to your home first, then into the battery, and anything left over is exported.
The saving is the electricity you no longer buy, plus the payments for what you export, at the prices you enter. It doesn't include the standing charge, which stays the same. On a cheaper overnight tariff, it's measured against that same tariff with no solar or battery.
Solar peaks at midday, but most homes use the most in the evening. A battery stores the midday surplus for later, so you buy less from the grid and export less.
The share link carries your answers so whoever opens it sees the same results. It keeps only the letters at the start of your postcode, such as BS, never your full address.
| Value | Used For | Basis | Source |
|---|---|---|---|
| Solar yield | Solar generated each hour | Monthly output per kWp for 17 UK regions, from PVGIS for a south-facing 35° roof with 14% system losses, then adjusted for your roof's direction and pitch with 20% ground reflection. A typical year of sunny and dull days from PVGIS for Bristol spreads it across the year. | PVGIS (© European Union, JRC) |
| 430 W | Panels to fit | A typical output for a modern house panel. Check your installer's panels. | Typical trade figure |
| 26p / 55p | Electricity price and standing charge | The price cap for 1 October to 31 December 2026, national averages for England, Scotland and Wales by direct debit: 26.32p per kWh and 54.83p a day. | Ofgem: price cap rates |
| 0% VAT | Electricity price | The price cap includes VAT, which is 0% on domestic electricity in England, Scotland and Wales from 1 October 2026 to 31 March 2027. | HMRC: Revenue and Customs Brief 10 (2026) |
| 2,500 kWh | A typical home's use | Ofgem's typical domestic consumption for a medium user from 1 July 2026. | Ofgem: revised typical consumption values |
| 12p / 4p | Export payment | The best fixed export tariffs pay around 12 to 15p per kWh; many suppliers' standard Smart Export Guarantee rates are nearer 4p. Rates change often. | Suppliers' published export tariffs |
| 8p / 15p | Overnight price | Electric car tariffs charge around 8p overnight (Octopus quotes from 7.6p); Economy 7 nights are nearer 15p. | Octopus Energy: smart tariffs. Economy 7: typical figure |
| 90% | Battery losses | Round-trip efficiency, split evenly between charging and discharging, as Tesla lists for the Powerwall 2. Newer batteries can do a little better. | Tesla: Powerwall 2 datasheet |
| 2,500 kWh | Car charging | 8,000 miles at about 3.5 miles per kWh is around 2,300 kWh at the car, and charging loses roughly a further tenth. | Typical figure |
| 3.68 kW | Network approval warning | EREC G98 lets a home connect and then notify up to 16 A per phase, about 3.68 kW on a single-phase supply, counting every inverter including a battery's. Above that, the network has to approve it first under G99. | ENA: Distributed Generation Connection Guide (2026) |
| Use through the day | When the home uses electricity | The share of each day's use in each hour and month, more or less in the daytime depending on how often someone is home, and half of each hour's use in short bursts of 6 kW, like a kettle or oven. In a home heated by electricity, heating takes 55% of the use outside car charging, mostly in winter. | Our own estimate, as a typical home |
| £25 per kWh | Suggested battery size | A bigger battery is suggested only while each extra kWh saves at least £25 a year, roughly what it needs to pay for itself. | Our own estimate |
The prices can all be changed above, and should be, from your own bill. "Typical" figures are what the trade commonly works to, with no single published source. Referencing a standard or manufacturer describes where a value comes from. It does not mean this tool is certified against it.
Fitting solar and batteries? ProWorks takes each install from quote to invoice and keeps it on a service schedule.
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