Solar Panel and Battery Calculator for UK Homes
Find out how many panels you need, what they will cost, and your savings — including battery storage
How the Calculator Works
Enter your postcode, property type, roof details, and energy usage to receive a personalised estimate in under two minutes. The tool uses local solar irradiance data for your area and accounts for roof orientation, pitch, and shading to estimate annual generation in kilowatt-hours (kWh).
Results include recommended system size, estimated installation cost, annual savings compared to your current electricity spend, income from the Smart Export Guarantee (SEG), CO2 reduction, and payback period. If you opt to include battery storage, the calculator sizes that too.
System Sizing
Get a recommended size based on your roof area, electricity usage, and occupancy patterns. Most UK homes benefit from a 3-6kW system with 10-18 panels.
Cost Estimates
See estimated installation costs including panels, inverter, mounting, and labour. Prices range from £5,000 to £12,000 depending on system size.
Savings & Payback
Compare annual savings on electricity bills plus income from exporting surplus energy. Most systems pay for themselves within 8-12 years.
How Many Solar Panels Do I Need?
The number of panels depends on your property size, electricity usage, and the wattage of each panel. Modern 400W panels need roughly 1.7-2 m2 of roof space each. Here is a quick reference by home size:
| Property | System Size | Panels | Annual Output | Estimated Cost |
|---|---|---|---|---|
| 1-2 bed flat or terrace | 2-3 kW | 6-8 | 1,600-2,500 kWh | £5,000-£7,000 |
| 3 bed semi-detached | 3-4 kW | 10-12 | 2,500-3,400 kWh | £6,000-£8,000 |
| 4-5 bed detached | 5-6 kW | 14-18 | 4,000-5,000 kWh | £8,000-£12,000 |
Enter your details above to get a personalised panel count based on your actual roof space and energy consumption.
Do I Need a Solar Battery?
Without a battery, you typically use 40-50% of the electricity your panels generate. The rest is exported to the grid at low SEG rates (4-15p/kWh). A battery stores surplus energy for the evening and overnight, raising self-consumption to 70-80% and cutting your reliance on grid electricity further.
Match capacity to your evening usage. A 5 kWh unit suits a couple or small home, while a family of four typically benefits from 9.5-13.5 kWh. Adding storage costs £2,000-£5,000 but saves an extra £200-£400 per year. Our calculator includes sizing for this when you select "Include battery" in step 3.
Ready to take the next step? Find MCS-certified solar installers near you or explore our air source heat pump guide if you are also considering a heat pump. Already have solar? Try our heat pump calculator.
Frequently Asked Questions
How many solar panels do I need for my home?
Most UK homes need between 10 and 14 panels for a 4kW system, which suits a typical 3-bedroom house. The exact number depends on your roof size, electricity usage, and the wattage of each panel. A south-facing roof with minimal shading will generate the most electricity. Use our calculator above for a personalised estimate.
How much do solar panels cost in the UK in 2026?
Installation costs range from £5,000 to £12,000 depending on system size. A 3kW system (1-2 bed home) costs around £5,000-£7,000, a 4kW system (3 bed) costs £6,000-£8,000, and a 6kW+ system (4-5 bed) costs £8,000-£12,000. Prices include panels, inverter, and mounting. Battery storage adds £2,000-£5,000.
What size solar battery do I need?
Match your battery capacity to your evening and overnight electricity usage. A 5 kWh battery suits a small home or couple, while a 10-13 kWh battery is better for a family of four. Our calculator sizes this automatically based on your energy profile.
How long do solar panels take to pay for themselves?
They typically pay for themselves within 8 to 12 years in the UK, depending on your electricity usage, system size, and whether you export surplus electricity via the Smart Export Guarantee (SEG). After the payback period, you benefit from free electricity for the remaining 15-20 years of the panel lifespan.
What size system do I need?
It depends on your annual electricity consumption and available roof space. A 3kW system suits a small household using 2,500 kWh per year, while a 4-5kW setup is better for a family using 3,500-4,500 kWh. If you plan to add an EV charger or heat pump, consider going larger at 5-6kW.
Are solar panels worth it in the UK in 2026?
Yes. With electricity prices above 24p/kWh, 0% VAT on installations, and the Smart Export Guarantee paying for surplus energy, typical savings are £800-£1,200 per year. They also increase property value and reduce your carbon footprint by around 1 tonne of CO2 annually.
Should I add a battery to my system?
A battery stores surplus energy for use in the evening and overnight, increasing self-consumption from around 40% to 70-80%. Storage costs £2,000-£5,000 but can save an additional £200-£400 per year. It is particularly worthwhile if you use most electricity in the evening or want backup power during outages.
How accurate is a solar panel calculator?
Online calculators provide estimates within 10-15% of a professional survey. Ours uses postcode-specific irradiance data, real electricity tariff rates, and your roof details to give a realistic estimate. For exact pricing, we recommend getting 2-3 quotes from MCS-certified installers.