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Existing Solar Panel installation - structural roof calculation check

Solar Photovoltaic (PV)

Last Post by scrchngwsl 3 hours ago

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ian-devon

(@ian-devon)

New Member Member

Joined: 19 hours ago

Posts: 1

Topic starter 19/07/2026 4:35 pm [#3109]

we are in the process of selling our property which has an existing 10 panel installation. The house was built in 1985 and has standard 'w'/ fink roof trusses at 600mm centres . The installation was carried out by the previous owners in 2008. Our buyers solicitors is requesting structural roof calculations to prove the install is OK. The panels were installed as part of a FIT mcs installation and we have advised the original mcs acredited installers would have assessed the roof as part of their remit and installation, but the solicitor is still asking for structural calcs. The orginal installer is no longer in business so I can't get any more info from them.

Has anyone had this issue before, or is able to assist in providing calcs to show the roof is OK? From what I can find out using AI is the roof of this age is able to support this number of panels, but I probably need more info to get the house sale over the post.

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hml1827

(@hml1827)

New Member Member

Joined: 18 hours ago

Posts: 1

19/07/2026 5:53 pm

In 2008 there was no requirement to provide structural calculations for PV installations. The system has obviously been operating for 18 years without the roof collapsing, so there is no real issue with the installation.

This is typical behaviour from conveyancers who love to find some irrelevant nit to pick which causes unnecessary stress to sellers. My response would be to say that if the purchasers aren't happy that I would get the installation removed so there will be no question of an inadequate roof, but the purchasers will lose quite a lot of future income (assuming that the system is on the original FIT.)

Of course that demands that you are prepared to stand up to these annoying people, but my experience is that they will usually back down.

👍

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JamesPa

(@jamespa)

Illustrious Member Moderator

Joined: 3 years ago

Posts: 5177

19/07/2026 7:31 pm

@hml1827 I couldn't have put it better, possibly with the exception of adding that it's stress for buyers as well as sellers.

I'm fully expecting similar when I eventually sell. The solar panel mounting on my flat roof is unconventional, and of course there are no structural calculations, but it has worked for 14 years and the only reasonably conceivable failure mode would require a local tornado in a very specific location.

If (for example) St Paul's Cathedral were to come up for sale, would the same apply. Let's exhume Sir Christopher Wren to find out how it was designed and some of the builders as well to check that they followed the drawings to the letter.

This post was modified 16 hours ago 4 times by JamesPa

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.

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scrchngwsl

(@scrchngwsl)

Estimable Member Member

Joined: 4 years ago

Posts: 96

20/07/2026 9:21 am

In our experience, the buyer usually pays for any surveys they want or that have been recommended to them as part of the building survey. I would kindly suggest that if the buyer has any concerns, they instruct a survey themselves or pay a professional to do a desktop calculation from easily attainable measurements. We paid for all sorts of surveys on a property we ended up walking away from as there would have been too much remedial work. But it would have been unreasonable to expect the sellers to spend their own money to satisfy our doubts, provide ammunition for us to negotiate the price down, or walk away entirely.

(Probably what happened was the RICS building survey flagged the solar panels as something they should check, and so they are checking. I would be surprised if the buyer really has a problem with it themselves but rather are doing it in good faith because an authority/professional advised them to.)

This post was modified 2 hours ago by scrchngwsl

ASHP: Mitsubishi Ecodan 8.5kW
PV: 5.2kWp
Battery: 8.2kWh

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