In short, no you don’t, but we will have to add a few caveats to that answer.     Roof based solar system must not stick out more than 200mm from the roof/wall surface it is mounted on. If the system is on a flat roof, the panels must be less than 1m in height above the highest part of the flat roof excluding any chimneys. They must also be over 1m away from any external edges of the roof.      If you are lucky enough to have a business in an area of outstanding natural beauty, or land with similar restrictions, then you can’t have anything on a roof slope or wall facing the road.    New planning rules mean ground-mounted solar arrays of up to nine square metres don’t need planning permission if they are less than 4m tall and you can only have one ground mounted system for each building.