CROSS Safety Report
Concern about PV installations
This report is over 2 years old
A reporter who has been pricing PV installations for portal frames would like to draw the attention of CROSS to concerns regarding issues that are emerging within the industry.
Key Learning Outcomes
For PV panel suppliers, installers, and homeowners:
All roofs should be appraised by a competent and suitably qualified engineer for the suitability of accommodating PV panels
Inspection by a competent person should be carried out to ensure the works are installed in accordance with the design intent
For civil and structural design engineers:
Load effects of snow and wind uplift acting on the roof structure due to PV panels should be carefully considered, particularly for sliding snow
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A reporter who has been pricing PV installations for portal frames would like to draw the attention of CROSS to concerns regarding issues that are emerging within the industry. There seems to be, they say, evidence of PV companies buying design software and having a go themselves without any training or supervision by a structural engineer.
Given the number of collapses of buildings in Scotland in the winters of 2009/10 and 2010/11 due to the snow loads, the lack of regulation and training for those allowed to purchase and to use this software presents risks. In the opinion of the reporter there is the potential for failure.
In addition, the reporter’s company has received enquiries from PV companies seeking 'remote surveys' for their installations and asking for a 25 year guarantee that the structures will carry the newly applied loads!
The reporter understands that it is not a requirement to submit structural calculations under building regulations for a PV installation (not so - see comments below), but this does not offer any protection to the public against injury should wind suction cause a panel to come off the roof, or indeed if panel loads push a portal design to the limit! He feels that there is a justifiable case for building regulations being applied to such installations in the interests of public safety.
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Further to this report and the comments, I have done a straw poll amongst those here who have had PVs installed on their houses (admittedly a small sample) and in no case was it treated as a material alteration and consequently the structure has not been assessed for the additional load. One of the manufacturer / installers of the ‘hot water panel systems’ that we have contact with had the same view. I would also have concerns about the design of fixings particularly the uplift case. I think that as most of these systems are installed under Competent Persons schemes that in practice the Local Authorities take a relaxed attitude particularly as it is considered to be a good thing on sustainability grounds. My personal experience is that triggering a request for structural justification for a material alteration is far less likely than a material change of use. When I put an extra floor on an existing building it was the coincidental material change of use that was used by the Local Authority to request more information I suspect that is because the definitions and requirements are better defined and wider in scope. Please keep up the good work in producing these reports, they are useful triggers for raising items for our Engineers to think about.
Expert Panel Comments
Expert Panels comment on the reports we receive. They use their experience to help you understand what can be learned from the reports. If you would like to know more, please visit the CROSS-UK Expert Panels page.
The installation of solar PV panels is a material alteration under the building regulations and needs assessment. In England this is to be done either under a competent persons scheme (such as the MCS scheme) or the local authority requires notification. Some competent person’s schemes only operate for electrical requirements of the regulations and then need the local authority to check other relevant aspects such as Parts A and C of the building regulations.
Issues of loading on existing roofs whether wind or snow or dead therefore come under control. Clearly there is a need to assess whether an existing roof structure can carry the extra load and that applies globally and locally (at fixing points). But there are additional concerns.
In the past CROSS has reported on many cases of danger following parts becoming detached from roofs. It is essential that panels are properly fixed down against the very high suction loads that might occur. In areas of higher snow load sudden thaws can cause snow slides with significant impact and danger if the slides fall on people or adjacent lower lying roofs.
It is essential that panels are properly fixed down against the very high suction loads that might occur
Are concerns likely to increase?
The potential for large slides might exist given the nature of panel surface material. The concerns are likely to increase as pressure to reduce energy consumption grows. Insufficient attention being paid to structural integrity is not new on small works. The examples quoted above all relate to competence and so far, the solar panel industry is unregulated.
Notwithstanding this the installation of solar panels is covered by the CDM Regulations and hence all those involved have statutory duties to safeguard others. It may be that a code of practice could be a good starting point. The Scottish Government has published a report: Risk assessment of structural impacts on buildings of solar hot water collectors and photovoltaic tiles and panel – final report.