Wolverton Swimming and Fitness Centre in Milton Keynes faced the same problem that every leisure facility in the UK is grappling with: an enormous, unavoidable electricity bill that keeps climbing year on year. In 2025, the centre worked with Spirit Energy to install a 377.97 kWp rooftop solar PV system to take a meaningful chunk of that bill off the books, and to lock in a degree of price certainty for the next 25 years.
Swimming pools and fitness centres are among the most energy-hungry public buildings in the UK. Pool water heating, air handling and dehumidification, gym equipment, lighting, and showers all run for the bulk of the day, every day the facility is open. The result is a long, steady daytime electricity demand that simply cannot be turned down without affecting service quality.
Three things make this a serious commercial issue:
- The load is non-negotiable. You cannot tell members the pool is closed because wholesale gas prices spiked overnight. The electricity has to be bought, whatever the price.
- Grid electricity is volatile and rising. UK commercial electricity rates are tied to wholesale markets, global gas prices, government policy, and grid maintenance costs. A facility operator has no real lever to pull on any of those.
- Carbon reporting and net zero commitments are tightening. Public leisure facilities are increasingly expected to demonstrate measurable progress on emissions, not just intent.
In short, the centre had a high, predictable load running through the middle of every single day, paid for at a rate it had no control over. That is exactly the kind of cost profile solar PV is designed for.
Our work with Wolverton focused on filling the available roof space efficiently and matching the centre's substantial daytime demand. The final design is a 377.97 kWp rooftop solar PV array made up of 586 AIKO G-MCH72-645-SF-DG 645W monocrystalline panels, with an active PV cell area of approximately 1,583 m². The panels are fixed to the trapezoidal sheet metal roof using a Clenergy PV-ezRack Trapezoidal mounting system, at an inclination of 10° and an orientation of 162° from south.
The DC array feeds three inverters: 3 x SolarEdge SE100K
The inverters are housed in a top floor riser cupboard, keeping the main electrical plant tidy, indoors, and protected. SolarEdge SDM630-Modbus-MID metering is included for accurate generation measurement, and the system is connected to an online monitoring portal so the team can review live and historical performance from any browser.
To forecast performance, we used our own in-house modelling, developed and refined over the commercial systems we have designed since 2010. The system is estimated to generate 283,478 kWh of clean electricity per year, the bulk of which will be consumed directly on site to offset grid imports.
Solar PV is most valuable when the building is using power at the same time as the panels are producing it. When the sun is up and the panels are generating, Wolverton is already pulling significant load. Almost every kWh produced by the array goes straight into running the pool plant, the air handling units, the lighting, and the rest of the centre, displacing grid electricity in real time at around 26p per kWh.
This is the structural reason leisure facilities are so well suited to large rooftop arrays. The roofs tend to be vast and uncluttered. The daytime load is consistent. And the operational savings show up on the very first invoice after commissioning. There is no need for batteries, no need for sophisticated time-of-use tariffs, just a large array on a busy building.
Wolverton is a busy public facility, so the project was planned around minimising disruption to staff, members, and pool users. Scaffolding and edge protection were included in the package, allowing the installation team to work safely at height across the full footprint of the roof.
The trapezoidal metal roof suited a non-penetrative clamp-based mounting solution, which preserves the roof warranty and keeps weather integrity intact. DC cabling runs internally from the roof down to the riser cupboard, where the three SolarEdge SE100K inverters are installed and wired into the building's existing electrical supply. G99 protection is in place to comply with network operator requirements for systems above 50 kWp.
Spirit Energy managed the full process internally, from feasibility study and structural calculations through to DNO application, planning prior approval, installation, testing, and commissioning. As an MCS-accredited, NICEIC-approved, and RECC-registered installer, every element of the work was signed off to industry standards.
With Wolverton's high daytime demand, solar is forecast to supply 32% of the centre's annual electricity, with the remaining 68% drawn from the grid. That ratio reflects a building that uses a lot of power, full stop. Even a 377.97 kWp system, which is one of the larger rooftop arrays we install, only meets a third of the load because the underlying consumption is so high.
That should not be read as a limitation, it should be read as the point. A third of a very large bill is a large saving, and that saving repeats every single year for the life of the system.
Wolverton's solar system delivers substantial financial returns:
- First year electricity bill savings of £63,215.
- An internal rate of return (IRR) of 36%.
- A payback period of just four years.
- A net present value (NPV) of £1,341,319 over the 25 year system life.
These savings will compound over time. The fixed performance of the array, paired with a rising cost of imported electricity, is what drives the long-term return.
Generating 283,478 kWh of clean electricity a year directly displaces electricity that would otherwise have been produced by the UK grid mix. In its first year of operation, the Wolverton system is expected to offset 63,782 kg of CO₂ emissions. Over the 25 year design life of the system, that figure runs to well over a million kilograms of CO₂ avoided.
For a public leisure facility serving the local community, that carbon saving is more than just a number on a report. It demonstrates that local services can play an active role in reducing emissions while also reducing operating costs, which is exactly the kind of dual outcome public sector buildings should be aiming for.
Wolverton Swimming and Fitness Centre is a strong example of why solar PV makes such practical sense for leisure facilities. High, consistent daytime demand, generous roof space, and rising grid electricity prices all combine to produce a system that pays for itself quickly and keeps producing returns long after that.
If you operate a swimming pool, gym, sports centre, or any facility with significant daytime electricity use, a properly designed solar PV system can deliver the same kind of impact. Spirit Energy has been designing and installing commercial solar since 2010, and we handle the full process in-house, from feasibility study through to commissioning and ongoing monitoring.
To discuss what solar could do for your building, get in touch on 0118 951 4490 or request a bespoke quotation through our website.