Solar PPA for mega-sheds (xxl warehouses)

2026 indicative PPA profile

Typical system size	2-5MWp
Year-1 tariff	9-11 p/kWh
Year-1 saving	£280k-£700k
Parent sector	Warehouses & Logistics

Roofs measured in football pitches

The XXL big-box shed changes the conversation entirely, because the constraint stops being the roof. At 25,000 to 50,000 m² of unbroken deck, a single mega-shed carries 2-5MWp of panels — enough generation that the project is sized more by grid connection and offtake than by available area. That scale is exactly why these buildings attract the keenest numbers in the whole sector, with electricity often landing at 9-11 p/kWh and bills falling by £280k-£700k a year.

Design it in, don't bolt it on

Most mega-sheds are speculative builds — developers put up the shell before a tenant signs — which opens a window that retrofits never get. When the array is planned into the structure, roof pitch and orientation can be optimised for yield, the frame designed to carry panel weight without later strengthening, and the grid connection sized generously from day one. A PPA arranged at shell stage, before fit-out, then travels with the building to whoever eventually occupies it.

The landlord-tenant question

Because the developer builds and the occupier uses, someone has to reconcile who funds the array and who buys the power. A green lease with an embedded supply agreement is the usual answer, and getting it drafted early avoids a stand-off after practical completion.

• Roof area exceeds what on-site load can consume alone
• New-build stage allows structural and orientation optimisation
• Green-lease terms settle the funding and offtake split up front

Model the shell before you commit

Whether you develop or occupy, the economics turn on the offtake terms. Read how a solar agreement actually operates in our plain-English mechanics guide, weigh the structures against each other in the side-by-side comparison, and place the big-box case within the wider warehouse and logistics sector.