How big is the solar system installed at Geoff Cox Automotive?
Alliant Energy installed a 40kW solar PV system using 68 panels paired with a 30kW inverter. The installation took 3 days from arrival on site to commissioning.
Project overview
Geoff Cox Automotive is a trusted family car dealership in Derby. A 68-panel solar PV system was designed and installed to power the showroom, saving £6,816 a year on electricity bills — equating to £346,152 over 25 years.
The challenge
Like most car dealership operations, Geoff Cox Automotive 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 40kW array using 68 high-efficiency mono-PERC panels, paired with a 30kW hybrid inverter. The 30kW 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 3 days, scheduled around the customer's operating hours to avoid downtime. Work was carried out by Alliant Energy's directly employed Experienced 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 Geoff Cox Automotive approximately £6,816 on electricity costs, with a payback term of 5.8 Years and a projected total ROI of 780%. Over the 25-year warranted life of the panels, the cumulative saving is forecast at £346,152 — 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 8 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 Geoff Cox Automotive'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 car dealership sector
Car Dealership 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 Geoff Cox Automotive project demonstrates how the model scales for this kind of operation.
System
40kW
Panels
68
Inverter
30kW
Install
3 Days
Project FAQ
How much does Geoff Cox Automotive save each year?
Geoff Cox Automotive saves approximately £6,816 per year on electricity, with projected lifetime savings of £346,152 over the system's 25-year guaranteed performance period. The payback term is 5.8 Years, delivering a total ROI of 780%.
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 8 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.
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