150 kW Solar + Battery on a London Serviced Apartment Building

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 92-unit branded serviced apartment building in Zone 2 London, operated by a major international aparthotel brand. 8-storey post-2010 development with flat roof, common-area amenity (lounge, gym, breakfast room), and individual apartment-level metering. Annual electricity 580,000 kWh (common areas) plus tenant in-apartment billing through individual meters. Brand commitment to 100% renewable electricity by 2030.

The brief

Deploy on-site solar covering common-area electricity load, sub-meter rebate structure for in-apartment surplus, integrate with brand sustainability platform, secure G99 grid connection in capacity-constrained inner London network, complete within the brand’s 2030 SBTi target trajectory.

The modelled system

150 kW rooftop array on the flat roof with 100 kWh LFP battery for evening common-area load coverage. UKPN G99 application — phased to accelerate first-phase commissioning given inner-London grid capacity constraints. Brand sustainability platform API integration. Common-area sub-metered rebate structure passing surplus generation value to tenants via reduced apartment service charge.

The numbers at year one

• Annual generation: 138,000 kWh
• Self-consumption: 82% (common area + battery-stored evening discharge)
• Year-1 saving (common area only): £36,000
• Capex: £175,000 (solar £140k + battery £35k); £131,250 after AIA shield
• Effective payback: 3.6 years
• Common-area sub-meter rebate to tenants: approximately £8,000/year across 92 units
• Brand sustainability platform contribution: 14% reduction in property Scope 2 emissions