Is Your Warehouse Roof Suitable for Solar Panels?

Solar panels add approximately 12-15 kg per square metre to your roof, including mounting hardware. Most modern warehouse roofs built after 2000 are designed to handle this additional load without reinforcement. However, older steel portal frame structures may need a structural survey to confirm capacity.

A qualified structural engineer will assess your roof purlins, rafters, and column loadings. The survey typically costs between £1,500 and £3,000 depending on warehouse size, but this investment prevents costly problems later. Many installers include a basic structural assessment in their free survey.

Wind uplift is equally important. Warehouse roofs in exposed locations or coastal areas face higher wind loads. The mounting system must be designed to resist both downward dead loads and upward wind forces, particularly at roof edges and corners where uplift is greatest.

Warehouses built before 2000 may have asbestos cement roof sheets. Solar panels cannot be mounted directly onto asbestos roofing because the material is too brittle and any disturbance releases dangerous fibres.

If asbestos is present, you have two options. Over-cladding involves installing a new metal roof over the existing asbestos sheets, creating a suitable mounting surface while encapsulating the asbestos. This typically costs £30-£50 per square metre. The second option is full asbestos removal and re-roofing, which costs more (£40-£80 per square metre including disposal) but gives you a completely new roof with a 40+ year lifespan.

Many warehouse owners combine asbestos re-roofing with solar installation. The combined project often qualifies for better financing terms because the new roof extends the useful life of the building, improving the asset value that secures the loan.

Systems up to 50kW typically connect to your existing electrical supply without major infrastructure changes. The inverter feeds into your main distribution board, and excess generation exports to the grid automatically.

Between 50kW and 1MW, you will need a G99 application to your Distribution Network Operator (DNO). This process takes 45-90 working days and may require grid reinforcement if local capacity is constrained. Your installer handles this application, but it should be started early in the project timeline.

Systems above 1MW require more detailed grid studies and potentially transformer upgrades. The costs can be significant (£20,000-£100,000+), but for large warehouses the savings justify the investment. The 2023 removal of the 1MW planning restriction for industrial rooftop solar has opened up much larger installations.

Three-phase power supply is essential for commercial solar systems above 3.68kW. Almost all warehouses already have three-phase supply, making this a non-issue for the warehouse sector.