How big is the solar system installed at The Westminster London Hilton?
Alliant Energy installed a 75.03kWp solar PV system using 171 panels paired with a SolarEdge inverter. The installation took 2 weeks from arrival on site to commissioning.
All case studies
Hospitality
The Westminster London Hilton
75.03kWp system saving £178,134 a year for The Westminster London Hilton.
Project overview
Maximising available roof space available, we’ve installed a 75.03 kWp solar PV system generating over 66,000 kWh of energy annually with a return on investment of fewer than three years! Building sustainable 'green' hotels is at the heart of Hilton’s 2030 ESG commitment, and The Westminster London, Curio Collection by Hilton, proudly aligns with this vision to create a more sustainable future in hospitality. With this 75.03kWp rooftop solar panels, generating 66,000 kWh of renewable energy annually, this innovative system offsets energy consumption across our hotel operations reducing our carbon footprint by an estimated 15,420kg of CO2 each year. Partnering with Alliant Energy for this project, reaffirms our dedication to a greener tomorrow in hospitality.
The challenge
Like most hospitality operations, The Westminster London Hilton faced a structural exposure to wholesale electricity prices — a cost line that doubled for many UK businesses between 2021 and 2023 and shows no sign of returning to pre-crisis levels. With significant daytime load and suitable roof space, on-site generation was the obvious lever, but the project needed to stand on its own commercial merits: predictable payback, manufacturer-backed warranties, and zero operational disruption during install.
The solution Alliant Energy designed
Following a structural roof survey and DNO capacity check, Alliant Energy specified a 75.03kWp array using 171 high-efficiency mono-PERC panels, paired with a SolarEdge hybrid inverter. The SolarEdge platform was chosen for its export-management capability and remote firmware updates, allowing the array to be tuned over its life without site visits. Surplus generation is exported to the grid under a Smart Export Guarantee tariff, providing a secondary revenue stream alongside the primary saving on imported electricity.
Install & commissioning
The full installation completed in 2 weeks, scheduled around the customer's operating hours to avoid downtime. Work was carried out by Alliant Energy's directly employed MCS-registered engineers — no subcontracted labour. The system was commissioned to G99 requirements, registered with the Microgeneration Certification Scheme, and handed over with monitoring access, electrical certification, and structural sign-off documents on the day of completion.
Financial outcome
In its first full year of operation the system is on track to save The Westminster London Hilton approximately £178,134 on electricity costs, with a payback term of 2.5 Years and a projected total ROI of 1000%. Over the 25-year warranted life of the panels, the cumulative saving is forecast at £3.80M — a figure that improves materially if grid prices continue their long-term upward trend, and that benefits from the UK's 100% full-expensing capital allowance for qualifying solar assets.
Environmental impact
The installation displaces roughly 71.2 Tonnes of CO₂ emissions every year compared with grid-sourced electricity. Over the system's 25-year design life that is the equivalent of removing more than The Westminster London Hilton's entire annual Scope 2 footprint several times over — a material data point for ESG, B-Corp and net-zero reporting frameworks.
Why it matters for the hospitality sector
Hospitality businesses typically run daytime electrical loads — refrigeration, machinery, IT, lighting, compressors — that overlap closely with solar generation. That overlap is what drives strong economics: every unit generated and consumed on-site replaces a unit that would otherwise be bought from the grid at full commercial rates. The The Westminster London Hilton project demonstrates how the model scales for this kind of operation.
System
75.03kWp
Panels
171
Inverter
SolarEdge
Install
2 Weeks
Project FAQ
How much does The Westminster London Hilton save each year?
The Westminster London Hilton saves approximately £178,134 per year on electricity, with projected lifetime savings of £3.80M over the system's 25-year guaranteed performance period. The payback term is 2.5 Years, delivering a total ROI of 1000%.
Was the project funded or paid for upfront?
This project was paid for directly by the customer. Under the UK's full-expensing capital allowance, the entire cost can be deducted from corporation tax in year one — improving the effective payback meaningfully for profitable companies.
What's the environmental impact?
The system avoids around 71.2 Tonnes of CO₂ emissions every year compared with grid-sourced electricity. Over a 25-year design life that's a material contribution toward Scope 2 reduction and any ESG or net-zero reporting commitments the business holds.
Could a similar system work for my business?
Probably — the same hardware platform (panels, hybrid inverter, optional battery) scales from roughly 10kW up to 1MW+. The deciding factors are roof area, daytime electricity use, current unit rate, and grid-connection capacity. Alliant Energy carries out a free desktop feasibility study and follow-up site survey before quoting.
More projects
Three ways to get started
Ready to find out what solar saves you?
Get a tailored quote in one working day. No obligation. No hard sell. Speak to a renewable energy engineer — not a salesperson — at a time that suits you.
