Solar PV vs heat pump: which intervention first?
For UK commercial property considering decarbonisation, solar PV and heat pump retrofit are the two highest-impact capital interventions. They are not alternatives — most successful programmes use both. But the sequencing question matters: which to install first, when, and how to maximise grant stack across the two.
Side-by-side comparison
| Feature | Solar PV | Heat pump |
|---|---|---|
| Capex per 100m² | £8,000-£25,000 | £15,000-£45,000 |
| Year-1 carbon saving | Lower (2-5 tCO2e per 100kWp) | Higher (10-30 tCO2e per 100kW heating) |
| Operating cost impact | Reduces electricity import | Increases electricity demand 50-150% |
| Grant routes | AIA, SEG, regional grants | Boiler Upgrade Scheme (BUS), AIA (PSDS and IETF closed) |
| Payback (post-tax) | 3-6 years | 8-15 years |
| Lifetime | 25-30 years | 15-20 years |
| Disruption | Roof works only | Major (pipe routing, plant room reconfiguration) |
| EPC band uplift | 1-2 bands | 1-2 bands |
| MEES 2027 compliance | Yes — typically sufficient | Yes — typically sufficient |
| Combined economics | Solar PV first, then heat pump | Combined IETF / PSDS / BUS grants stronger together |
Which one for your business? Real scenarios
Fossil-fuel heating + tax-paying limited company
Recommendation: Both, solar first. Solar delivers fast payback (3-6 years) and the electricity bill reduction funds heat pump retrofit later. The AIA on both (solar panels and heating systems are special-rate, so neither takes full expensing) creates a 25% effective discount on programme capex.
Pure office building with electric heating already
Recommendation: Solar PV. Heat is already electrified. Solar PV reduces import bill directly. Combined with battery storage for evening load.
Public sector (school, NHS, council)
Recommendation: Combined PSDS application. PSDS strongly favours integrated solar + heat pump + insulation. Solar alone usually loses to integrated bids.
Energy-intensive manufacturer
Recommendation: fund the integrated package — solar + heat decarbonisation + process electrification — on tax relief and finance. The IETF that would have match-funded it closed in July 2025 with no successor.
MEES 2027 deadline driving urgency
Recommendation: Solar PV first. Cheapest single intervention for EPC band uplift. Heat pump can follow in 2028-2030 ahead of MEES B threshold.
Key deciding factors
- Heat decarbonisation is harder; solar PV is faster. Sequence solar first to fund heat pump retrofit later.
- Combined applications outscored standalone solar while the PSDS and IETF were open; both are now closed (November 2024 and July 2025). Integrated programmes still pay on their own economics.
- Heat pump retrofit dramatically increases electrical demand — making solar economics dramatically stronger when both are deployed.
- MEES 2027 / 2030 deadlines favour solar (1-2 bands per £25-£60/m²) over standalone heat pump (1-2 bands per £180-£400/m²).
- For sites already on electric heating, solar PV is the only commercial-solar-relevant intervention.
- Existing roof condition often forces solar before heat pump (re-roof + solar + heat pump in sequence).
Comparison FAQs
Should I do solar PV or heat pump first?
Almost always solar PV first. Faster payback. Reduces electricity bill. Funds heat pump retrofit. Heat pump retrofit then improves solar economics further.
Can I get one grant for both?
The PSDS and IETF both strongly preferred integrated applications, and both are now closed (PSDS November 2024; IETF July 2025). The Boiler Upgrade Scheme is heat-pump-only. Combined packages still outperform standalone solar on their own economics.
Does heat pump make solar more economic?
Yes — significantly. Heat pump increases electrical demand 50-150%, increasing solar self-consumption and absolute electricity bill savings.
Is MEES 2027 better solved by solar or heat pump?
Both lift EPC by 1-2 bands. Solar PV is cheaper per band uplift (£25-£60/m² vs £180-£400/m²). Solar wins for tight 2027 deadline; heat pump may be required for 2030 EPC B.
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