We speak to Bryan McGrory of BMG Surveys about whether the current structural standards for retrofit solar installations are ensuring that the solar boom is properly executed.
October 29, 2026
This summer, the UK’s rooftop solar installations broke record levels and, in the face of increasing energy costs, are projected to continue to do so.
The government also just announced a low- and zero-interest loan scheme for domestic clean energy installations, meaning that demand for rooftop PV is likely to increase once again.
"The UK has enormous ambitions for rooftop solar, but ultimately we're installing that technology onto an existing building stock of hugely varying age, construction, condition and structural capacity," Bryan McGrory told Solar Power Portal this week.
McGrory is managing director of BMG Surveys, which has specialised in structural assessment and engineering support for solar PV since 2011. In that time, McGrory says the firm has assessed over 500,000 roofs and supported more than 3,000 clients across domestic, commercial and public-sector solar installations.
The central tension facing the industry, according to McGrory, is one of balance: How do we scale rooftop solar without structural due diligence becoming either a box-ticking exercise at one extreme, or an unnecessary barrier to deployment at the other?
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McGrory and his team have been working closely with MCS on the structural elements of MIS 3002, the standard for structural roofing requirements, and in dialogue with Local Authority Building Control (LABC) and the National Association of Professional Inspectors and Testers (NAPIT) about how related industries approach these issues in practice.
Beyond the technical standard itself, McGrory points to wider conversations that need to happen around competency, professional indemnity insurance, and the responsibilities placed on installers when it comes to structural compliance, all areas that could benefit from greater clarity across the industry.
A common assumption might be that structural concerns are a side effect of solar's recent rapid growth. McGrory is clear that this is not the case. MIS 3002 has contained requirements relating to the suitability of existing roof structures, and the competence of those checking them, for many years. Yet in BMG's experience, the way these requirements are understood and applied remains inconsistent.
"The issue is not that solar has suddenly grown too quickly. It is that we still need to make sure the existing requirements are properly understood, followed and checked by people with the right competence."
Currently, the MCS guidance gives what McGrory describes as "screening checks not structural checks".
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McGrory points to fundamental concerns with the calculation methodologies currently presented within Table 1 of the standard.
Specifically:
Table 1 includes a loading assumption of 0.785kN/m², which BMG has been unable to substantiate against recognised structural design standards.
Another method uses a 0.75kN/m² imposed loading allowance, whereas BMG's position is that 0.60kN/m² is the more appropriate basis for the relevant roof types and design periods.
BMG has raised these concerns directly with MCS and is working with the organisation on proposed amendments.
McGrory's concern is that the existing rules are too open to interpretation, and that software tools, while in some cases useful, cannot substitute for genuine structural understanding.
"Software companies have incorporated these simplified methods into their workings. And basically, it's a computer programme that's generating an answer."
"You need to be suitably qualified to say whether a roof is suitable for solar panels, but ultimately a computer programme is not going to know."
For McGrory, the issue of competence is central. He believes MCS needs to make it clearer who can be considered suitably competent to make structural decisions — a bar that would likely require an engineering qualification.
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He says that to qualify as competent, an engineer needs to understand load paths and how the entire building envelope works.
"We wouldn't expect a roofer to certify an electrical installation, and we wouldn't expect an electrician to assess the structural adequacy of a building. So why are we accepting structural assessments from individuals who may have little or no understanding of structural engineering, simply because they have access to software that produces a pass or fail result?”
McGrory isn’t arguing for eliminating software from the assessment process altogether, but rather ensuring that whoever is running that software understands what they are looking at, and that the information being input is actually correct.
"The concern isn't whether someone knows how to operate the software. It's whether they have the knowledge and competence to correctly identify the roof construction, understand how the structure works and recognise whether the information they're entering is actually correct.
"If someone doesn't understand the structure they're assessing, how can they be confident that the information they've entered accurately reflects the building in the first place?
"Software can be a useful tool, but it doesn't make someone structurally competent. A suitably competent person needs to understand the structure, the limitations of the assessment and when further engineering input is required."
Beyond the specifics of calculation methods and qualifications, McGrory frames BMG's broader campaign as being centred on demonstrable competence.
The approach BMG has been advocating for is that regulatory bodies need to be auditing competence, not simply assuming it exists because an individual has access to assessment software.
McGrory also notes that in solar installations on commercial buildings, the same issues don't come up as often, because insurers, landlords and building owners often need the structural reports as a requirement of any funding mechanism.
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Molly Green
Section Editor, Informa
Molly joined the team in 2024 and has led coverage on the UK sites. Now shifting to a more global view, Molly is interested in how legislation shapes market dynamics, covering the intersection of policy design, investment patterns, and energy transition pathways.
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