Building Control and MCS sign-off for a DIY PV installation

[andymb]

A question for those who have installed their own PV arrays please : how did you get the required bits of paperwork following your installation?

As I understand it, I need to get the roof signed off by both building control and by MCS but if you are not an approved installer how did you get around this?

 

My current situation is that I'm trying to re-roof a barn which may be developed at a later date (we are converting an adjacent barn to live in)

My main aim is to re-roof this barn purely to preserve the building - in order to save on the cost of slate (planners have specified Westmoreland green slate) I'd like to install in-roof panels (quite like to look of Viridian Clearline) so for the time being the panels won't be connected to anything, however I would like to "future proof" myself so that if the time comes that we are going to develop this building, I have the necessary paperwork.

 

My preferred plan would be to install the Panels alongside my roofers

 

If anyone has faced a similar situation I'd really appreciate it if you could share your solution

 

many thanks, Andy

[ProDave]

BC have not questioned my DIY solar PV.  Why would they?  MCS is only needed for the now defunct FIT or to claim the present export payment scheme.

 

If the barn is adjacent to your house, connect them and use them.

[TonyT]

BC will be interested in the effect the panels will have on the roof timbers.

 

dave- yours isn’t on the house or garage so they have no interest.

[nod]

You will probably find that BC are only interested in your slate certificate 

It will never come up who has done what 
If you need a certificate for the PV I’m sure there is someone online that will sell you one 

[andymb]

ProDave: The plan would be to connect and use the panels when we get that far - I'm just having trouble specifying the rest of the system before I know whether we will be grid connected or not.

 

If we did manage to tie in to the grid, but planned NOT to export any power (so as to avoid the need for an MCS certificate) what would we do with the excess? I've read about "dumping" the excess into electric heaters/immersion heaters, but my understanding is that the DNO's will not allow this is you to do this if you are grid tied and but only importing electricity ?

 

another concern is that viridian has told me that their warranty is only valid if installed by an accredited (i.e MCS) installer

[newhome]

I have solar thermal rather than PV but building control insisted on seeing something from my SE that supported the panels being on the roof. They also wanted something that assessed the fire risk that seemed odd to me at the time. 

 

 

[TonyT]

I have a small MCS certified install on my roof, next year I hope to self install more panels on my garage roof( once garage has new roof). And for new inverter etc

i will be self installing and only advising the DNO afterwards.

[SteamyTea]

1 hour ago, newhome said:

seeing something from my SE that supported the panels being on the roof

This was something that got added to MCS about a decade ago, to do with wind and snow loading.  Installations on old roofs have also been a concern.

[andymb]

TonyT - I hear what you are saying but I think that unless I can get the rest of the system up and running and and signed off (which is next to impossible at present) I am worried that questions will be later be asked about the panels if we do manage to tie into the grid.

 

Newhome - I don't think that there will be too much difficulty in getting something from the SE to say that the roof can take the panels - surely they must be lighter than the slate which the roof is currently covered with!

[newhome]

38 minutes ago, andymb said:

Newhome - I don't think that there will be too much difficulty in getting something from the SE to say that the roof can take the panels - surely they must be lighter than the slate which the roof is currently covered with!

Indeed but they’re ticking boxes I think. My SE had no issue with confirming what was wanted. 

[newhome]

1 hour ago, SteamyTea said:

This was something that got added to MCS about a decade ago, to do with wind and snow loading.  Installations on old roofs have also been a concern.

Yes I believe that many buyers’ reports say that the roof may not be adequate for the solar panels and when they pay for the full structural survey they come back with the solar panels are ok on the roof ?. 

[ProDave]

44 minutes ago, newhome said:

Yes I believe that many buyers’ reports say that the roof may not be adequate for the solar panels and when they pay for the full structural survey they come back with the solar panels are ok on the roof ?. 

Yes I know someone that pulled out of a purchase (against my advice) because of this.  The house had 4kWp solar PV on the original high FIT for 25 years and that would have been transferred to the new owner. But the surveyor raised doubts about the roof structure and the panels.

 

They ended up buying an inferior house without panels.

[TonyT]

58 minutes ago, newhome said:

Yes I believe that many buyers’ reports say that the roof may not be adequate for the solar panels and when they pay for the full structural survey they come back with the solar panels are ok on the roof ?. 

They also advise that there has been some movement during the history of the building too??

 

I think a roof would have to pretty rubbish not to support panels, considering  they are spread over many trusses.

 

just more paperwork to justify the pen pushers.

 

[SteamyTea]

2 hours ago, newhome said:

Yes I believe that many buyers’ reports say that the roof may not be adequate for the solar panels and when they pay for the full structural survey they come back with the solar panels are ok on the roof

This is why, I believe, it got added to the system.  Stops all that sort of nonsense.

[Gus Potter]

Hello Andymb

 

The inline system pv panels tend to weigh less than the slates. But if you want to really future proof the roof you may want to allow for an extra 20 - 25 kg / square metre of dead load applied to the rafters. 

 

To put this into a bit of context. Broadly speaking the weight of a modest vaulted concrete tiled roof may weigh about 1.0 kN/ (~ 100 kg)square metre on plan, slates may weigh a bit less depending on type etc. Added to that is an extra 0.6 kN (~ 60 kg) per square metre to account for what is called roof access load. If you live in parts of say Aberdeenshire the snow load can be greater than the access load.  These loads get factored up in different ways but you can see that roughly the extra weight of the solar panels is a fairly modest increase in loading.

 

If you really want to future proof the roof then it's worth looking at what ultimate form it may take. For example will you settle for a flat ceiling at wall head height..? do you want a bit of vaulting.. this may take the form of what is called a "raised tie truss" or do you want to go for the full volume right up to the ridge. This will influence the future proofing more than the weight of the solar panels as the whole method of constrution of the roof changes.

 

Maybe the best thing to do is to take the approach that you are going to go for the full internal vaulting, design for that as you can lower ceilings etc later on. The material and creating the strong points for the roof supports will cost more but the labour cost should increase at a lesser rate when you consider the roof as a whole. For example you'll probably need to bed the wall plates, provide gutters, flashings and so on. In other words you get to keep the materials to some extent.

 

Alternatively, it may be that you are able to create a habitable attic space? in which case the floor loadings are an important part of this cost / benefit calculation. As always it's all to do the available funds!

 

Once you get a handle on the structure then this sets / underpins matters for any accreditations etc you may feel you need for the actual pv installation.

 

 

 

 

[andymb]

Hi Gus,

 

Many thanks for your input - the roof structure is already decided for me - it is an exiting purlin roof that I'm hoping to re-slate (trying to avoid having to buy any more slates though)

 

when I was talking about future proofing I was meaning in terms of the necessary paperwork/certification for the PV panels.

 

Am I being unduly worried about having an MCS certificate for the installation of the panels?

 

Would any of you know if you need an MCS certificate for all of the different various components of the PV system or does the MCS certificate apply only to the whole system (I.e could I get the MCS certification when I have the inverter/battery bank etc installed)

 

thanks for all and any input, Andy

[TonyT]

You only need an MCS certificate if you are claiming FIT, and then it has also to be installed by an accredited installer.

 

you can buy grid tied inverter, panels you feel and connect up, notify the DNO and away you go- no FIT payment though

[SteamyTea]

11 hours ago, andymb said:

Would any of you know if you need an MCS certificate for all of the different various components of the PV system or does the MCS certificate apply only to the whole system (I.e could I get the MCS certification when I have the inverter/battery bank etc installed)

Apart from the 'electrical and structural' side, the MCS specifies approved modules.  You can have any inverter you like, as long as it is acceptable to the DNOs.

Battery systems are basically an add on, so as long as they are properly fitted and are safe, then they are not part of it.

 

As a general note with MCS, there is a lot of paperwork that has nothing to do with the actual fitted systems, this includes quality assurance systems and staff monitoring, or as we used to call it, traceability, dispute resolution etc. This is where part of the MCS cost is, you are paying for things that may never be needed.

[andymb]

ok thanks for your help everybody - I think that I'd better get an MCS approved installer on board

Edited December 20, 2020 by andymb
posted before post was complete