Solar install structural problem

f418

Member
Livestock Farmer
Good morning,

I’ve been looking at getting solar panels fitted to a 30m x 20m steel framed shed with timber purlins and tin sheet roof. I’ve paid £1k for a structural survey that tells us that the purlins are not strong enough and that they would need doubling up to support the extra load as they might buckle and fail under worst case snow and wind scenarios.

The existing purlins are 75x225mm and span 5.70m. The plan was to put 2 rows of 16 panels across the width of the roof however it now looks as though is not possible as the additional weight is going to take it to 20% over capacity.

I believe this is to comply with the strict MCS regulations and I have been told that if I get them fitted by a company who is not MCS compliant and don’t get a MCS certificate then our insurance would be invalid or if we were to sell the farm we’d have to prove that the panels had been installed to MCS standard.

How do other farms completely fill their shed roof with panels?

Apart from looking at a ground fixing solution or installing less panels to bring the load down it looks as though I’ll have to give up on the idea.

Thanks in advance for any suggestions.
 

peterinnorfolk

Member
Mixed Farmer
Location
West Norfolk
Would avoid skipping out on the MCS-certified installer, I believe you also can't get paid for export without a certificate. Where in the country are you? Might be worth chatting to an installer who deals with these, or were you planning to install yourself?
 

f418

Member
Livestock Farmer
I have been going through a MCS approved installer and they won't proceed with installing on the roof unless the extra work is done, they're looking at a ground installation now. I'm located just outside Durham, didn't intend installing them myself however it is crossing my mind, if only I knew someone that would help wire them up and keep me right!
 

steveR

Member
Mixed Farmer
Good morning,

I’ve been looking at getting solar panels fitted to a 30m x 20m steel framed shed with timber purlins and tin sheet roof. I’ve paid £1k for a structural survey that tells us that the purlins are not strong enough and that they would need doubling up to support the extra load as they might buckle and fail under worst case snow and wind scenarios.
How do other farms completely fill their shed roof with panels?

Apart from looking at a ground fixing solution or installing less panels to bring the load down it looks as though I’ll have to give up on the idea.
It will surely not be that difficult or costly, to put additional purlins in?

Steel, Z purlins or timber to suit, spaced between the existing purlins, fix them with wood Tekscrews from underneath, and roofing tekscrews from the roof into the purlins.
 

f418

Member
Livestock Farmer
It will surely not be that difficult or costly, to put additional purlins in?

Steel, Z purlins or timber to suit, spaced between the existing purlins, fix them with wood Tekscrews from underneath, and roofing tekscrews from the roof into the purlins.

I priced the 30 new timber purlins up at around £1200+vat, then structural surveyor has specified that they are bolted to existing purlins at 500mm spacing with M10 bolts and toothed washers so that's 330 holes to drill and fix. Also would need to hire a cherry picker in, probably not that difficult to do it's just all adding up and the time it'll take to do.
 

steveR

Member
Mixed Farmer
I priced the 30 new timber purlins up at around £1200+vat, then structural surveyor has specified that they are bolted to existing purlins at 500mm spacing with M10 bolts and toothed washers so that's 330 holes to drill and fix. Also would need to hire a cherry picker in, probably not that difficult to do it's just all adding up and the time it'll take to do.
Fully understand the hassle factor, especially as it now has to be done to Surveyor standards!! The zed purlins would be a much easier to retro fit to the steel work, but again, now the professionals are involved, it is more awkward.

If it had all been done beforehand, I doubt that it would have been anywhere as much grief... ;)
 
Last edited:

Nitrams

Member
Location
Cornwall
Not sure if this helps but you can get different strength mounting solutions for the panels that can span wider purlin spacings, so may offer a solution
 

Punch

Member
Arable Farmer
Location
Warwickshire
Ground mount. Easy to maintain. Get the perfect direction and angle for your latitude.
We’ve got 28kW on shedroof and thinking about moving them to ground mount. After 10 years the shed roof is now 27 years old and starting to leak. Quote I’ve had to remove and replace after repairing roof and it’s cheaper to remove and ground mount!
Panels likely to still be in place after 50 years if performance reduction carries on at the slow rate we’ve seen in 10 years.
 

renewablejohn

Member
Location
lancs
Good morning,

I’ve been looking at getting solar panels fitted to a 30m x 20m steel framed shed with timber purlins and tin sheet roof. I’ve paid £1k for a structural survey that tells us that the purlins are not strong enough and that they would need doubling up to support the extra load as they might buckle and fail under worst case snow and wind scenarios.

The existing purlins are 75x225mm and span 5.70m. The plan was to put 2 rows of 16 panels across the width of the roof however it now looks as though is not possible as the additional weight is going to take it to 20% over capacity.

I believe this is to comply with the strict MCS regulations and I have been told that if I get them fitted by a company who is not MCS compliant and don’t get a MCS certificate then our insurance would be invalid or if we were to sell the farm we’d have to prove that the panels had been installed to MCS standard.

How do other farms completely fill their shed roof with panels?

Apart from looking at a ground fixing solution or installing less panels to bring the load down it looks as though I’ll have to give up on the idea.

Thanks in advance for any suggestions.
Why would you go to the cost of a structural survey when you would bolt the external mounting frame directly to the steel frame.Strength of the existing purlins is totally irrelevant its the strength of the steel frame which is important.
 

f418

Member
Livestock Farmer
Why would you go to the cost of a structural survey when you would bolt the external mounting frame directly to the steel frame.Strength of the existing purlins is totally irrelevant its the strength of the steel frame which is important.
The solar installer has to get a structural survey done before they can install any solar panels as part of the MCS certification. The brackets that fix the panels are to be fixed down-over spread over 3 wooden purlins not going across to each steel frame of the shed.

Are you saying there's a different way to fix the panels directly through to the steel frame of the shed rather than to the wooden purlins? Do you have a link to the type?
 
Why would you go to the cost of a structural survey when you would bolt the external mounting frame directly to the steel frame.Strength of the existing purlins is totally irrelevant its the strength of the steel frame which is important.
I'd assume a framework to support the panels fixed through the roof to the steelwork completely independent from the roof purlins is far more expensive than just fixing a basic framework through into the purlins, let alone the fact that it's probably too complicated for a lot of solar installers.
 

renewablejohn

Member
Location
lancs
The solar installer has to get a structural survey done before they can install any solar panels as part of the MCS certification. The brackets that fix the panels are to be fixed down-over spread over 3 wooden purlins not going across to each steel frame of the shed.

Are you saying there's a different way to fix the panels directly through to the steel frame of the shed rather than to the wooden purlins? Do you have a link to the type?
You dont need to fix to purlins there are plenty of systems that just bolt to the steel structure quite often used for canopies like covering car parks etc. Not a fan of MCS just another quango to extract money out of renewable technology.
 

steveR

Member
Mixed Farmer
I have seen pics of one setup, when the panels had galv (I think) external supports, resting on top of the sheets, fixed to the steel work below.
Just thinking this one....

Surely, Z purlins could be put on top of an existing roof to provide structural support for a solar panel framework? Put them directly above the existing timber purlins to make for easier fitting, but main fixing directly to steel frame of the building below? Alternatively, maybe use the ally rails as found on commercial solar, again mounted as above?
 

Doing it for the kids

Member
Arable Farmer
Just thinking this one....

Surely, Z purlins could be put on top of an existing roof to provide structural support for a solar panel framework? Put them directly above the existing timber purlins to make for easier fitting, but main fixing directly to steel frame of the building below? Alternatively, maybe use the ally rails as found on commercial solar, again mounted as above?

Would work well but don’t hit the roof and have to replace any sheets 🤣😬
 

f418

Member
Livestock Farmer
You dont need to fix to purlins there are plenty of systems that just bolt to the steel structure quite often used for canopies like covering car parks etc. Not a fan of MCS just another quango to extract money out of renewable technology.

I've asked the surveyor about using a system like you say and he doesn't think a system exists that allows you to fix directly to the steel frame.

Please can you send a link or picture showing the type of system you are suggesting?
 

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