Commercial solar savings calculator
Enter your electricity spend to estimate the system size, annual saving and payback for solar panels for schools. Indicative only, not a quote.
Indicative estimate
- Recommended system
- 90 kWp
- Annual saving
- £23,940
- Simple payback
- 3.4 years
- Capital-allowance relief
- £20,250
- CO₂ saved
- 17.7 t/yr
- 25-year saving
- £598,500
Assumptions: ~950 kWh per kWp per year (UK average); install cost £1,130 per kWp, the midpoint of this guide’s planning range of £1,000–£1,260 per kWp (the upper end is the DESNZ 2025/26 median for 10–50 kW systems); exported units at an assumed 5p/kWh; the default unit price of 24p/kWh is close to the DESNZ average non-domestic price for the first quarter of 2026 (24.14p). No capital-allowance relief is shown, because most schools and academies do not pay corporation tax. These are illustrative defaults; your figures depend on roof, shading, load profile, tariff and tax position. This tool does not store any data you enter.
Calculator FAQs
How accurate is this calculator?
It gives an indicative estimate from stated assumptions: roughly 950 kWh generated per kWp per year, an installed cost of £1,130 per kWp (the midpoint of this guide’s planning range) and an assumed 5p/kWh export rate. Your real figures depend on your roof, orientation, shading, load profile and tariff, so a precise figure needs your half-hourly meter data.
What is self-consumption and why does it matter?
Self-consumption is the share of solar you use on site rather than export. On-site use saves the full electricity price, while exported units earn only the lower Smart Export Guarantee rate, so a higher daytime load means a shorter payback. The slider lets you set your daytime usage share.
Does the estimate include tax relief?
No. Capital allowances such as the Annual Investment Allowance reduce corporation tax, and most schools and academies do not pay it, so the calculator shows no tax relief. An independent school with a taxable trading arm should take advice on its own position.
Is this a quote?
No. It is an indicative estimate to help you scope the opportunity. A real proposal needs your meter data, a roof assessment and a grid check from the installer you choose.