From June, MIS 3002 V6.0 requires every MCS-licensed solar PV installation in the UK to be checked, before installation, to confirm it can carry the array
However, it only requires that the check is carried out by a “suitably competent person” – it never says that person must be a structural engineer. This creates a worrying gap for commercial projects, writes Sahir Raihan
From 18 June, MIS 3002 V6.0 makes one thing mandatory across the UK: before any MCS-certified solar PV system goes on a roof, the structure must be checked to confirm it can carry the array. For an industry that has spent years adding solar to commercial rooftops on assumptions that were rarely tested, this is welcome and overdue discipline.
But there is a gap in how the duty is written, and building professionals are well placed to see it.
The standard requires the check to be carried out by a “suitably competent person”. It does not define that person as a structural engineer. For a simple, standard domestic roof, that latitude is reasonable. On a commercial building it is not.
A structural engineering calculation
Confirming that a specific structure can safely carry an added load for the next 25 years, accounting for wind uplift, snow accumulation and the existing condition of the frame, is a structural engineering judgement. A certified mounting kit tells you what the array demands of the roof. It does not tell you whether that particular roof, at its actual age and condition, can take it.
This is familiar territory for anyone working in building compliance. The structural safety of the building, with the proposed addition, still has to be demonstrated under Building Regulations Approved Document A and the calculations sit in the Eurocodes: BS EN 1991 for wind and snow actions, BS EN 1990 for load combinations, with BRE Digest 489 for the PV-specific wind pressures. None of that is satisfied by a visual once-over.
The scale is not theoretical. Across 575 UK commercial rooftops assessed for solar feasibility, one in three needed structural intervention before panels could go on. Seventy-eight percent of flat-roof ballasted installations needed their ballast reconfigured to pass a combined load check.
Sixty-two percent of ageing asbestos-cement roofs failed a wind-uplift adequacy check. These are not failures a non-specialist inspection reliably catches. They are failures you find by calculating.
Mind the gap
There is a second reason the question matters for commercial work, and it sits outside the standard altogether. No lender, insurer or technical adviser will underwrite a 25-year rooftop asset on a tick-box check by an unqualified person. They want structural evidence signed by an engineer, because they are the ones carrying the risk if the roof fails.
The market has already set the bar higher than the regulation does, and procurement and specification teams are the ones who feel the gap when a project reaches lender or building control review without it.
A minimum, not best practice
For specifiers and main contractors, the practical implication is straightforward. The structural pathway belongs in the brief from the start, not as an afterthought at sign-off. Where a desktop assessment can confirm feasibility before commitment, it should run early. Building the structural step into procurement is far cheaper than redesigning an array after the loads are found wanting.
The honest reading of MIS 3002 V6.0 is that it sets a floor, not a standard of good practice. A “suitably competent person” is the minimum the regulation will accept. On a
commercial roof, that competent person should be a structural engineer because confirming a building can safely carry a load for a quarter of a century is, by definition,
structural engineering.
For anyone specifying, building or signing off commercial solar after 18 June, the question to carry through the process is not “have we met the standard?” It is “who
actually checked the roof, and were they qualified to?”
The post Mind the gap: The structural blind spot in the new rooftop solar mandate appeared first on Planning, Building & Construction Today.
