Commercial solar finance calculator
Compare buying outright, 100% finance and a PPA. Enter your electricity spend to see the upfront cost, monthly payment and year-one net cashflow for each. Indicative only, not a quote.
Indicative system
147 kWp
Annual energy benefit
£39,051
| Route | Upfront | Monthly cost | Net cashflow (yr 1) | You own it |
|---|---|---|---|---|
| Buy outright | £124,950 | £0 | +£3,254/mo | Yes |
| 100% finance (HP / loan) | ~£0 | £2,191/mo | +£1,063/mo | At end |
| PPA | £0 | Pay for power | +£813/mo | No |
Buying outright also gives an indicative £31,238 of year-one tax relief through the Annual Investment Allowance. Finance can be cash-flow positive from year one when the saving beats the payment. A PPA needs no capital but the funder keeps ownership and the export income.
Get these routes quoted for realIndicative estimate using standard 2026 UK assumptions; not a quote and not financial advice. Actual finance and PPA terms vary by provider and covenant strength. This tool does not store anything you enter.
Calculator FAQs
How does this calculator work?
It sizes an indicative system from your electricity spend and daytime usage, estimates the annual saving, then compares three funding routes: buying outright, 100% finance such as hire purchase or a green loan, and a PPA. It uses standard 2026 UK assumptions and is an estimate, not a quote.
What assumptions does it use?
About 950 kWh generated per kWp per year, an installed cost near £850 per kWp, a 14p Smart Export Guarantee rate for exported units, and your own inputs for unit price, daytime usage, finance term, finance rate and PPA discount. Your real figures depend on your roof, load profile and the actual finance terms offered.
Why is the finance route sometimes cash-flow positive?
If the annual energy saving is larger than the annual finance payment, the project puts money in your pocket from year one even though you paid nothing upfront. Whether that happens depends on system size versus consumption, your tariff and the finance rate.
Is this a quote?
No. It is an indicative comparison to help you scope the decision. A real quote needs your meter data and actual finance or PPA terms, which we provide free as part of a feasibility.