Solar Panel Installation
in Letchworth

Letchworth is the one town on this site where a green light from the council is only half a green light. Letchworth Garden City Heritage Foundation runs a Scheme of Management, and its Solar Panel Design Principles, revised May 2026, state that most dwellings in the town require its prior written consent for external alterations. The Foundation is explicit that this requirement is separate from the permission required from the local authority under planning and listed building legislation and the building regulations, and its FAQ answers the obvious follow-up directly: permitted development does not exempt you, because any external alteration to your property will also require its Consent. The council's own 2023 Article 4 report calls the Foundation's regime a separate regime to the planning system. So a Letchworth installation needs two parallel checks, and we open the Foundation application at survey rather than after the design is signed off.

Which rules apply depends on which of the Foundation's two Character Areas your address falls in, and for solar the two are very different. In the Heritage Character Area, the May 2026 Design Principles say panels must be located on rear elevations and not visible from the public realm, must not sit on any street-facing elevation, and must not be visible from the public realm on side elevations either. In the Modern Character Area, panels are acceptable on any roof slope provided they meet the other requirements. Homes of Special Interest, listed at page 38 of the Heritage Character Area Design Principles, can be treated differently again, and the Foundation publishes a character area lookup for individual addresses. For a Letchworth house that lookup decides whether the sunniest slope is even available, so we run it before modelling yield or counting panels.

Letchworth's roofs were designed rather than accumulated, and the council's conservation area appraisal says so: roofs are either strong gabled or hipped forms with pitches of 45 to 50 degrees, clad in plain clay roof tiles with carefully positioned red brick chimneys, and swept and laced valleys are a feature of many of them. The appraisal also records that slate was generally avoided because Parker and Unwin felt it resembled industrial terraces, so slates are not characteristic of the Garden City. Two things follow. Plain clay tiles and laced valleys need careful fixing and flashing rather than a standard hook-and-rail assumption, and the steep pitch moves the numbers: re-running PVGIS at 45 degrees instead of 35 leaves a south-facing Letchworth roof effectively unchanged but costs an east slope about 3% and a west slope about 4%. We model your measured pitch, not a default.

Foundation consent covers far more than the panels. The May 2026 Design Principles apply to installations on roofs, walls and outbuildings, to free-standing arrays within the curtilage, and to associated equipment such as battery storage units and other ancillary infrastructure, which also require consent. Batteries, inverters, connectors and switches must not be visible from the public realm, and cabling must be run discreetly using existing cable and pipe runs wherever possible. The application wants a marked photograph or scaled drawing, preferably an aerial view or roof plan, a specification of the panels including size, colour and type, and the locations of batteries, inverters and cabling. Panels should preferably be black including the frames. On a Letchworth job we therefore fix battery position, cable route and the AIKO all-black panel spec before applying, not after.

Census 2021 shows why the first Letchworth question is often who owns the roof. Across the five Letchworth wards there were 14,754 households: 33.1% in terraced houses, 25.2% semi-detached, 19.5% detached and 19.2% in a purpose-built block of flats. On tenure, 57.4% of 14,763 households owned their home, 29.8% rented from a social landlord and 11.6% rented privately, so for well over a third of Letchworth households the roof decision starts with a landlord or freeholder, and the Foundation says a housing association tenant applies to the association rather than direct. On the grid side, UK Power Networks' own boundary data puts the SG6 centroid in its Eastern Power Networks licence area and its Stevenage/Luton operational area, so a Letchworth G98 notification or G99 application goes to UKPN and we submit it.