400 kW Solar + Heat Pump Pool Electrification at a Surrey Destination Spa
- System size
- 400 kW
- Annual saving
- £135,000
- Payback
- 4 years
- Location
- Surrey
Modelled worked example — the figures below are built from sourced 2026 UK cost and generation benchmarks for a property of this profile, not a claimed client project.
The hotel
An 80-room independent destination spa resort in the Surrey Hills with 25m pool, full spa with 14 treatment rooms, fitness suite, 90-cover restaurant, and substantial corporate-events and wedding business. AONB designation. Listed Grade II main house plus extensive unlisted estate buildings. Annual energy spend £290,000 (£195,000 electricity + £95,000 gas).
The brief
Combined electrification programme: replace existing gas pool heater with air-source heat pump, deploy estate-distributed solar, eliminate Scope 1 emissions from the property, and underpin the destination spa sustainability marketing narrative for the wellness-retreat segment.
The modelled system
400 kW estate-distributed solar array: 220 kW on the main spa block flat roof (unlisted), 110 kW on the stable-block roof, 70 kW on the function-suite extension. Air-source heat pump conversion of the pool plant (180 kW thermal capacity). Listed Building Consent secured for the stable-block roof — Grade II main house untouched. Combined capex £620,000 with AIA 100% first-year tax relief on the full amount.
The numbers at year one
- Annual solar generation: 375,000 kWh
- Self-consumption: 94% (pool plant + spa plant electric load absorbing solar generation)
- Year-1 combined saving: £135,000 (£105,000 electricity offset + £30,000 net gas-to-electric conversion saving)
- Capex: £620,000 gross; £465,000 after AIA + 50% FYA shield
- Effective payback: 3.4 years
- Scope 1 emissions reduced by 168 tonnes CO2e/year (gas pool plant eliminated)
- Wellness-retreat segment booking-rate uplift 16% in 6 months following lobby display deployment