The roof, rebuilt.
An address goes in. The site is rebuilt in 3D from a 1 m LiDAR surface and imagery, with obstructions where they actually are. Usable area is measured per roof. It is never assumed as a percentage.
Method
Built from the roof, not a rule of thumb.
Every site is rebuilt, then run. The formula, the inputs, and the source sit behind the figure. This is a feasibility screening, not a measurement you can build from.
The years, run.
8,760 hours of a typical year, with shading and temperature. Where meter data exists, generation is set against use, half-hour by half-hour. A kilowatt-hour used on site is worth more than one exported, so the right size depends on the goal.
The flags, named.
Wind actions are screened against BS EN 1991-1-4 and MCS installation standards. Added roof load is flagged where a closer look is due. The nearest substation is screened from network operator headroom data, with the source and date shown. Planning is screened as a route, not a consent. None of these replace the engineer, the network operator, or the planning authority.
The number, bounded.
Generation is modelled at P50, with a site-specific P90. Capital cost is a band, not a point. A firm installer quote replaces it. Returns are shown across that band, and the report says whether the recommendation changes across it. Modelled output has been compared with twelve months of metered generation from one operating commercial rooftop array, and sat inside the modelling tolerance. That is one comparison, not a validation programme.
Sources