Wind load is a critical design variable for rooftop solar PV installations because arrays installed above the roof surface create additional uplift and lateral forces not accounted for in the original structural design. The net effect depends on the site wind zone, local terrain category, building height, array tilt angle, and the gap between panels and roof surface.
UK engineers calculate wind loads to Eurocode 1 Part 1-4 (EN 1991-1-4) and the UK National Annex. The fundamental basic wind velocity varies across UK wind zones, with upland and coastal sites subject to significantly higher design loads. A Desktop Structural Roof Loading Report includes wind load calculations specific to the site address.