Yes, solar PV works excellently on flat roofs — and most UK warehouse roofs are flat or near-flat (5-15° pitch). Flat-roof PV is now mainstream commercial practice with mature mounting technology, well-understood economics, and strong customer adoption. This guide covers the practical considerations.
Ballasted vs mechanically fixed
Ballasted mounting uses concrete or steel weight to hold the PV array against wind uplift, no penetration of the roof membrane. Standard for membrane roofs and increasingly for profiled steel where roof warranty would be voided by mechanical fixing. Typical ballast load 15-20 kg/sqm. Mechanical fixing penetrates the roof to attach to structural purlins beneath. Lower dead load (5-10 kg/sqm) but penetrates the membrane — requires careful waterproofing detail.
Wind loading to BS EN 1991-1-4 (Eurocode 1)
All mounting designs must withstand site-specific wind loading per Eurocode 1. Coastal and exposed sites require higher specification. Most UK inland sites are within standard 25-30 m/s design envelope. We have completed installs at port sites with 35 m/s design wind speeds — design envelope is well-defined.
Tilt angle and orientation
Flat-roof PV is typically mounted at 10-15° tilt (vs 30-35° for residential pitched roofs). The lower tilt slightly reduces annual yield (~3-5%) but enables higher density and lower wind exposure. East-west orientation (panels facing both east and west on opposing rows) is increasingly common — better matches commercial daytime load profile than south-only.
Roof warranty preservation
Mechanical fixing often voids manufacturer roof warranties (Kingspan, Tata, Corus). Ballasted typically preserves warranty. We work with the roofing manufacturer on warranty preservation where critical to the project.
Common roof types we work with
Profiled steel (Kingspan, Tata Colorcoat): excellent — both ballasted and mechanical work. Single-ply membrane (PVC, TPO, EPDM): ballasted only — protect membrane with slip sheet or rubber pad. Modified bitumen: ballasted with care — verify waterproofing condition. Asbestos cement: cannot be retrofitted — combined re-roof + PV is the only path.