35 kW on a Grade II* Mayfair Townhouse Boutique Hotel

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

A 22-room Grade II* Georgian townhouse boutique hotel in Mayfair, London — one of the West End’s premium independent properties. Listed Building Consent requirements substantial (Historic England consultation mandatory). Annual electricity spend £75,000. Owner-operator with strong sustainability commitment and a corporate-events client base from financial-services and professional-services firms within walking distance.

The brief

Deploy solar in one of the most consent-constrained UK heritage hotel categories — Grade II* in central London conservation area, Westminster City Council planning, Historic England statutory consultation. The owner specifically wanted “the most difficult solar install in London” to demonstrate that any UK heritage hotel can deploy solar with appropriate design discipline.

The modelled system

35 kW rooftop array on the rear-facing roof slopes only — completely invisible from the public realm street view. Framed dark-grey panels with reversible flush-mount fixings (no roof structure penetration). Internal inverter siting in the existing services riser. Historic England statutory consultation managed across 14 weeks. Listed Building Consent secured in 18 weeks total. Capital purchase with AIA tax shield through corporate-events operating entity.

The numbers at year one

• Annual generation: 32,500 kWh
• Self-consumption: 91%
• Year-1 saving: £9,800
• Capex: £45,000 gross; £33,750 after AIA shield
• Effective payback: 3.4 years
• Corporate-events RFP win rate up 22% in following 12 months (substantial financial-services demand for sustainability-evidenced venue)
• Featured as exemplar Grade II* Listed Building Consent case study in the Solar Energy UK 2026 heritage guide