A 3 MW+ warehouse solar system is the mega-warehouse and data centre scale for UK commercial PV. With 5,500+ panels covering 18,000-30,000+ sqm of roof, fits the largest UK warehouse buildings. Per-kW capex drops below £700/kW at this scale. PPA financing essentially universal. Freeport ECA stacking delivers maximum economic uplift.
Typical 3+ MW system specification
Capacity: 3-5 MW typical. Panels: 5,500-9,200 modules at 540W. Roof area: 18,000-30,000+ sqm usable. Inverters: 4-8 central inverters typical. Annual generation: 2.75-4.6 GWh. Capex: £1.8-3.2m installed (£600-700/kW typical). AIA + FYA + Freeport ECA stacking: typically £700k-£1.4m year 1.
When 3 MW+ is the right size
Mega-warehouses 600,000+ sqft (Tesco, Sainsbury's, M&S NDCs; major 3PL flagship hubs). Port warehouses (London Gateway, Felixstowe, Liverpool Freeport). Data centres (Slough cluster, West London cluster). Major manufacturing facilities (JLR Halewood scale, Tier-1 supplier mega-plants).
Economics worked example — 3.4 MW data centre
3.4 MW install on West London colocation data centre. Capex £2.3m. Year-1 tax shield: £225k AIA + £462k FYA = £687k. Net cash cost £1.6m. Annual generation 3.15 GWh. At 96% self-consumption: £665k/yr saving + £6k SEG = £671k. Simple payback 4.1 years. After-tax cash 2.4 years. 25-year IRR 28%. Improves PUE from 1.42 to 1.36.
Common questions about 3 mw+ system
What's the largest warehouse solar install in the UK?
5+ MW installs are increasingly common at port warehouses and data centres. Theoretical maximum on a single building is around 8-10 MW (limited by roof area and DNO capacity). Multi-building portfolio installs can exceed 10 MW total — we have delivered 14.2 MW across 12 sites for a national 3PL.
How does PUE improvement work for data centres?
PUE (Power Usage Effectiveness) = total facility power / IT load. On-site renewable generation reduces grid-supplied component, mathematically improving PUE. 3.4 MW install on 60 MW IT-capacity data centre typically improves PUE by 0.05-0.08 — meaningful in customer audit comparisons.