Energy Saving Trust placed the average cost of a home solar panel system at about £6,100 in April 2026. That figure is a useful starting point, not a price list. A homeowner's final cost depends on capacity, equipment, roof access, scaffolding, electrical work, DNO requirements, installer support, and location.
Payback depends on how much generated electricity replaces grid imports, how much is exported, the tariffs applied, and how the household's demand changes over time.
What a complete quote should contain
Compare quotes with the same project boundary. Each should identify panel and inverter models, panel capacity in kWp, expected annual generation, mounting system, monitoring, scaffolding, electrical work, meter or consumer-unit assumptions, DNO work, warranties, VAT, and total cash price.
Ask for optional items to be separated. A battery, EV charger, bird protection, roof repair, optimiser, backup gateway, or extended warranty can make two totals appear incomparable.
A low price has little value if essential work appears later as a variation.
System size and roof constraints
A larger array usually costs more in total while sometimes costing less per installed kilowatt because fixed design, access, and labour costs are spread across more panels.
Useful capacity is limited by unshaded roof area, panel dimensions, structural conditions, planning, inverter design, DNO permission, and budget. Electricity use also matters. A household planning an EV, heat pump, electric hot-water system, or home working may have stronger future demand than its last bill suggests.
Do not assume a common 4 kWp package is automatically right. Ask why the proposed size matches the property and load.
Generation estimates
MCS installers provide an estimated annual yield using recognised methods and assumptions. Review orientation, pitch, shade, location, system losses, and any export limit.
Annual kWh is more useful than panel count. Request a monthly profile because UK production is strongly seasonal. A system can have a sound annual total while generating far less during winter evenings when the home uses more electricity.
Compare installer estimates and investigate large differences.
Self-consumption creates avoided-import savings
Electricity used directly in the home avoids buying the same amount from the supplier. Its value is therefore linked to the applicable import rate at that time.
Self-consumption depends on occupancy, appliances, heating, EV charging, controls, and willingness to shift loads into daylight hours. Dishwashers, laundry, water heating, and vehicle charging can sometimes be scheduled, but high-power equipment still needs appropriate circuits and controls.
Do not multiply all generation by the import tariff. Some energy will be exported, curtailed, or lost in storage and conversion.
SEG export income
Eligible surplus can earn a Smart Export Guarantee payment based on metered exports. Suppliers set their own rates, terms, and eligibility details, subject to scheme rules.
Export income equals eligible exported kWh multiplied by the applicable export rate. A high export rate can improve returns, but linked import tariffs, standing charges, time windows, battery restrictions, and contract terms may alter the household result.
Read the Smart Export Guarantee guide and compare offers using the SEG supplier framework.
A transparent annual-benefit model
Use three separate lines:
- Imported electricity avoided through direct solar use.
- Imported electricity avoided through useful battery discharge, after losses.
- SEG income from measured exports.
Then subtract expected finance cost, maintenance allowances, and likely equipment replacement. Inverters may not last as long as panels, and batteries have finite cycle and calendar life.
Run conservative, central, and favourable scenarios. Tariffs will change during a system that may operate for decades.
Payback calculation
Simple payback divides net upfront cost by estimated annual net benefit. A £6,100 system producing £700 of first-year benefit has a simple starting payback of about 8.7 years. That arithmetic does not account for tariff changes, degradation, maintenance, replacement, finance, or the time value of money.
A discounted cash-flow model is more complete. Even a spreadsheet that varies import prices, export rates, generation degradation, and inverter replacement is better than one fixed number.
Treat a quoted payback period as an assumption set to inspect.
Batteries change the economics
A battery may store midday surplus, charge cheaply from the grid, support time-of-use optimisation, or provide backup when correctly designed. It also adds upfront cost and energy losses.
Energy Saving Trust placed a typical 5 kWh battery system around £4,600, while noting a wider range based on type and size. Adding storage does not automatically shorten solar payback. Compare solar-only and solar-plus-battery models using the same load data.
See UK solar batteries and home storage before accepting a bundled return claim.
VAT and financing
Qualifying professionally installed solar in Great Britain currently carries a temporary zero VAT rate through 31 March 2027. Northern Ireland rules differ. Confirm the quote states the correct treatment and read UK VAT for solar.
Finance can make solar accessible but changes total cost. Compare cash price, deposit, interest rate, fees, term, early repayment, total repayable, and any security over the property. A monthly repayment below estimated bill savings does not prove the investment is cheaper overall.
Quote-comparison checklist
- Exact equipment and installed capacities.
- Annual and monthly generation estimates.
- Shade and roof assumptions.
- Included access, scaffolding, and electrical work.
- G98 or G99 connection responsibility.
- Export limitation and SEG assumptions.
- Product, workmanship, and insurance-backed warranties.
- Monitoring and service pathway.
- Cash price, VAT, finance, and total repayable.
- Solar-only and battery alternatives.
UK solar panel cost is easiest to judge when every assumption is visible. Choose the design that remains credible under conservative electricity use and tariff scenarios, rather than the quote with the shortest advertised payback.