Solar PV & Battery Sizing Calculator

See how much solar panels and a home battery could save you, and which sizes make sense for your home.

1. Your Home

Sets how much sunshine your area gets.

It's on your annual statement. A typical UK home uses about 2,700 kWh.

How is your home heated?

A heat pump or electric heaters put much more of your use in winter, when there's least sun.

Is someone usually home in the daytime?

Power used while the sun is up comes straight from the panels.

2. Your Tariff

Type of tariff

Economy 7 and electric car tariffs are cheaper overnight, so a battery can charge up cheaply and power your home the next day.

We've filled in today's price cap. 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.

3. Solar Panels

Add an array for each roof the panels go on. With one array you can leave the size blank for our suggestion, or enter 0 for a battery on its own.

4. Battery

The suggested size is where each extra kWh stops adding much saving.

Enter your postcode and how much electricity you use to see your results.

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.

How the Calculator Works

Hour by Hour, for a Whole Year

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.

What the Saving Means

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.

Why a Battery Helps

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.

Sharing Your Results

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.