Side-by-side comparison
Comparison: typical 5,000 sqm office considering solar PV vs ASHP retrofit.
| Factor | Solar PV | Air-source heat pump retrofit |
|---|---|---|
| Capex (typical 5,000 sqm office) | £300-450k | £300-800k |
| Year-one tax saving (limited co.) | £75-112k (100% AIA) | £75-200k (100% AIA) |
| Annual saving | £60-90k | £25-60k (vs gas) |
| Simple payback | 4-7 years | 8-15 years |
| EPC point uplift | 4-12 points | 8-20 points (gas → ASHP) |
| Operational disruption | None (rooftop) | 6-9 weeks (HVAC swap) |
| Scope 1 emissions reduction | No | Yes (eliminates gas) |
| Scope 2 emissions reduction | Yes (avoided grid) | Adds Scope 2 (grid-fed) |
| MEES 2030 contribution | Strong (4-12 SAP pts) | Strongest (8-20 SAP pts) |
| Maintenance complexity | Low (annual inspection) | Medium (annual servicing, F-gas) |
| Combined NPV (PV first, ASHP at end-of-boiler-life) | — | Highest 25-yr value |
The decision
Pick on the basis of your specific situation:
Solar PV
Best for: Most offices in 2026 — solar payback is materially shorter than ASHP retrofit. AIA delivers strong year-one tax relief. No operational disruption.
Air-source heat pump retrofit
Best for: Where gas boiler is at end-of-life (year 20-25), ASHP retrofit at boiler-replacement time is the natural moment. Combined with solar PV, full Scope 1+2 decarbonisation.
How we model it for you
For every office solar proposal, we model the relevant comparison options side-by-side. Send us your half-hourly meter data and roof plan via the quote form, and we'll return a fixed-price proposal within 7 working days with all relevant routes compared in your specific situation.