Which renewable technology has the best payback?

Solar PV typically has the shortest payback (6-9 years) due to relatively low installation costs and high self-consumption savings. ASHP payback is 8-14 years after the BUS grant. Battery storage is 8-12 years with time-of-use tariffs. GSHP has the longest payback (12-18 years) due to higher installation costs.

What is NPV and why does it matter?

Net Present Value (NPV) accounts for the time value of money — a pound saved in 10 years is worth less than a pound saved today. A positive 20-year NPV means the investment generates a real return above the discount rate. Higher NPV means a better investment.

Should I install solar PV and a heat pump together?

Combining solar PV with a heat pump is an excellent strategy. The PV generates free electricity during the day, which the heat pump uses for heating and hot water. This effectively gives the heat pump free-fuel operation during sunny hours, dramatically improving overall payback.

Does the BUS grant affect payback?

Yes, significantly. The £7,500 BUS grant reduces the net cost of an ASHP from approximately £12,000 to £4,500. This shortens payback from 15+ years to 7-10 years. The same grant applies to GSHP, reducing net cost from £24,000 to £16,500.

How does electricity price affect renewable payback?

Higher electricity prices improve Solar PV and battery payback (more value from self-generated/stored electricity) but worsen heat pump payback (higher running costs vs gas). Time-of-use tariffs with cheap off-peak rates significantly improve battery storage economics.

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Renewable Technology Payback Comparison

Compare payback periods and 20-year NPV for ASHP, GSHP, Solar PV, and battery storage side by side.

ASHP Installation Cost

GSHP Installation Cost

Solar PV Cost (4kWp)

Battery Storage Cost

Electricity Price

Gas Price

How We Calculate This

This calculator compares four renewable energy technologies side by side, showing installation cost, annual saving, payback period, and 20-year net present value for each.

Comparison methodology

ASHP/GSHP: Saving = gas boiler cost - heat pump running cost (after BUS grant)
Solar PV: Self-consumption value + SEG export income
Battery: Tariff arbitrage (peak - off-peak) x usable capacity x 365
NPV: Discounted cash flows over 20 years at chosen discount rate

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.