Solar Panels for Data Centres

Solar for UK Data Centres: Sizing Against 24/7 Load, PUE and Grid Constraints

A data centre is the hardest commercial building to power with solar, and that is exactly why the maths has to be done properly. Unlike a warehouse that runs daylight shifts, a colocation or hyperscale facility pulls a near-constant load 24 hours a day — so the question is never "can solar cover us" but "how much of the daytime baseload can we displace, and at what £/kWh." A rooftop or campus array generates only when the sun is up, while your IT halls and chillers run flat through the night. That mismatch caps a typical solar contribution at 20–40% of annual consumption, with the remainder met from the grid, a PPA, or battery time-shifting.

The single biggest lever is your PUE (Power Usage Effectiveness). A facility running at PUE 1.5 spends a third of its draw on cooling and overheads — load that peaks in summer afternoons, exactly when a solar array produces most. Self-generated solar feeding chillers and CRAC units at midday is the cleanest match a data centre gets, which is why we size the array against your cooling profile and half-hourly meter data, not the roof footprint. In southern England, sites in the Slough Trading Estate and wider Thames Valley and the London Docklands exchange clusters generate around 1,000 kWh per kWp a year; Midlands campuses around 950; northern and Scottish sites 850–880.

Connection is the other constraint. Any export above 50kW needs a G99 application to your DNO — SSEN across Slough and the Thames Valley, UKPN in London, NGED or SSEN elsewhere — and many high-density sites are already at the edge of their grid capacity, so an export-limited or zero-export design (consuming everything on-site behind the meter) is usually the fastest route to energised. At £0.75–£1.05 per watt, a 1MW behind-the-meter system costs roughly £750k–£1.05m and, after Annual Investment Allowance relief (~25% cash benefit at the corporation-tax rate), delivers a payback of around 3–4.5 years on grid prices that data centres pay at scale.

• Behind-the-meter first — zero-export designs sidestep DNO capacity queues and use 100% of generation on the IT and cooling load.
• Battery + demand response — storage smooths the solar-to-load gap and can earn DSR/grid-services revenue without touching uptime SLAs.
• Tier resilience preserved — solar and storage sit alongside, never inside, the N+1/2N UPS and generator topology, so resilience certification is unaffected.