Estimate how much solar panels could save you each year, how quickly they'll pay for themselves, and how much CO2 you'll offset.
Solar panels generate electricity from daylight, not direct sunshine. Even on overcast days, your panels produce power. The UK averages around 900 to 1,100 peak sun hours per year depending on where you live. Southern England gets roughly 4 hours of peak equivalent sunshine per day in summer and about 1 hour in winter. Scotland averages slightly less at around 3.5 summer peak hours.
A typical 4kWp system on a south-facing roof in the Midlands generates approximately 3,800 kWh per year. That's more than the average household's entire annual electricity consumption of 2,500 kWh. You won't use all of it directly (you'll be out during peak generation hours), but you'll typically self-consume 40-50% without a battery, or 70-80% with one.
A 4kWp system (around 10 panels) currently costs between £6,000 and £8,000 fully installed, including scaffolding, the inverter, and all wiring. Larger 6kWp systems run from £8,500 to £11,000. Prices have dropped roughly 15% since 2023 as panel manufacturing scaled up globally. VAT on residential solar installations is 0% until at least March 2027, saving you an immediate 20% compared to what you'd pay otherwise.
Installation typically takes one day for a straightforward south-facing roof. If you need additional scaffolding for access, or if your roof needs structural checks, add another half day and £300-500 to the cost. Always get at least 4 quotes from MCS-certified installers; prices vary significantly between companies, sometimes by £2,000 or more for the same system.
When your panels generate more than you use, the surplus feeds back to the grid. Under the Smart Export Guarantee, your energy supplier pays you for every kWh you export. Rates vary wildly between suppliers: Octopus Energy currently offers up to 15p/kWh on their Flux tariff (time-of-use), while others pay as little as 4p/kWh. A 4kWp system exporting 50% of its generation at an average of 8p/kWh earns about £152 per year.
A home battery (typically 5-10 kWh capacity) stores excess solar electricity for use in the evening. Costs range from £2,500 for a basic 5kWh unit to £5,000 for a 10kWh system like the Tesla Powerwall or GivEnergy All-in-One. Without a battery, you'll self-consume roughly 40-50% of your solar generation. With a battery, that rises to 70-80%, meaning you buy less from the grid.
The payback maths: if a battery costing £4,000 lets you self-consume an extra 1,500 kWh per year (saving 26.32p/kWh instead of earning 8p/kWh), the annual benefit is about £275. That's a 15-year payback on the battery alone. Batteries make more financial sense if you're on a time-of-use tariff where you can charge cheaply overnight (at 7p/kWh) and discharge during peak (40p/kWh). On those tariffs, battery payback drops to 6-8 years.
Solar panels require virtually no maintenance. There are no moving parts. Panels come with 25 to 30-year performance warranties (guaranteeing at least 80% output at year 25). Inverters last 10-15 years and cost £800-1,200 to replace. An occasional clean (once or twice a year if your panels are near trees) is all you need. Rain does most of the cleaning for you. Total maintenance cost over 25 years: roughly £1,500, almost entirely from one inverter replacement.