For houses and flats in England, most roof-mounted solar is permitted development (PD) if you meet key limits: keep panels below the roof's highest part (chimneys ignored) and no more than 200 mm off the wall/roof plane; avoid mounting on a street-facing wall in a conservation area;. For houses and flats in England, most roof-mounted solar is permitted development (PD) if you meet key limits: keep panels below the roof's highest part (chimneys ignored) and no more than 200 mm off the wall/roof plane; avoid mounting on a street-facing wall in a conservation area;. But there are traps: projection limits, flat-roof height caps, conservation area rules on a principal elevation, and special cases for listed buildings, Article 4 areas and stand-alone arrays. Below is a clear checklist (England first, with Wales, Scotland and Northern Ireland differences flagged). If solar equipment is to be installed on a flat roof on Article 2 (3)* land then the developer must apply to the local planning authority for prior approval. All the following limits must be met: On a pitched roof, panels should not be installed above the highest part of the roof (excluding the. A typical 4kW solar system needs around 20m² (215 sq ft) of roof space, though the exact area depends on panel size and household demands. This ensures the panels remain flush and don't disrupt the property's appearance or roofline. Panels must not exceed the roof's highest point Solar panels cannot be installed higher.