Solar Panel Cost Calculator
How does a solar cost calculator work?
A solar panel cost calculator estimates your installation cost (£5,000-£11,000), annual savings (£500-£1,100), and payback period (8-12 years) based on your specific circumstances: location, roof direction, system size, and electricity consumption. Our calculator uses PVGIS solar irradiance data for your postcode and Ofgem Q1 2026 electricity rates (24.5p/kWh). The estimate is indicative — get 3+ installer quotes for accurate pricing.
What the Calculator Estimates
- System size recommendation based on your electricity consumption and roof space
- Installation cost range for your recommended system size
- Annual electricity generation (kWh) based on your location and roof direction
- Annual savings (£) based on self-consumption rate and SEG export income
- Payback period — how many years until the system pays for itself
- 25-year total savings — lifetime financial benefit of your solar investment
- Carbon savings — tonnes of CO2 prevented over the system lifetime
Key Inputs That Affect Your Estimate
Location (postcode): Determines solar irradiance — southern England generates ~15% more than northern Scotland.
Roof direction: South = 100% of optimal. East/west = 80-85%. North = 55-60%.
Electricity consumption: Higher consumption = more self-consumption = more savings per kWh.
System size: Larger systems cost more but generate more — the calculator recommends the optimal size for your needs.
Battery: Adding a battery increases self-consumption from ~50% to ~80%, adding £200-£400/year in savings.
Source: PVGIS; Ofgem Q1 2026.
Calculator vs Real Quotes
The calculator provides an ESTIMATE. For accurate pricing, you need installer quotes based on a physical site survey.
Why quotes differ from the calculator: - Roof complexity (slate, flat, multi-level) affects installation cost - Shading not visible from satellite imagery - Consumer unit capacity or upgrades needed - Scaffolding access challenges - Specific panel and inverter brand selection
Use the calculator to: Understand the ballpark → then get 3+ quotes for accurate pricing.
Source: MCS installer pricing methodology.
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