Solar Panels - cables loose on roof?

[farmerdave]

Hello all,
We've just had some solar panels fitted to our house (not yet commissioned or fully paid for), but I have a few concerns about the installation so far, which I'd like to pick your brains about.

The main concern is that the cables connecting the panels loop down and rest on the slate roof under the panels and can move around quite a lot. I'm concerned that they will move around when the wind gusts in the wrong direction (we're on top of a hill in Northumberland and the winds can be extreme). In the short term this will be very irritating (living room is directly under roof - no loft) and in the longer term this could result in early failure of the system due to rapid wear and tear on the wires.
I would have expected that the cables would have been tied up to the rails out of the way - is this normal for them to hang down on the roof?
There are other aspects of the installation which to my untrained eye seem a bit unprofessional, so I'm wondering if the installers have been taking a short-cut.

Also, I was in the house the other night when the wind was moderate (not high) and I noticed a bit of banging coming from the array, maybe due to the fixings flexing a bit - hard to be sure but it wasn't the cables rattling. Is this normal; it usual for panels to give a little bit of noise in the wind? I don't want to be un-reasonably complaining to the installer!

Thanks,
Dave

 

[whinmoor]

Cables should be tied to the rails to prevent them rubbing against the roof surface. Cable ties cost pence and there's no excuse for not using them.

I would recommend getting the installer back to rectify this asap - preferably before any scaffolding is removed and certainly before you hand over your money.

 

[whinmoor]

Didn't answer the second question. Did they perform a structural survey and/or windload calculations prior to installing? It sounds like your location is pretty windy so it's rather different from an urban setting.

 

[farmerdave]

Thanks Whinmoor, that's what we thought, but is there any official guide or anything that says that; I can see the installer turning round and saying "no, that's fine, that's how they're always done". I can't see them wanting to come back and spend a day removing the panels again and re-install them tying up the cable. I found an installation guide for the panels, but it doesn't go into cable management...

Frankly I haven't been very impressed with either the company we've been dealing with or the installer (presumably a third party company) - the installers work shows signs of unprofessionalism (eg. the inverter is in a hatch in a stud wall - they must have installed the isolator switches first, then finding there wasn't room for the inverter to fit, instead of shifting things along a bit, they just took a large hammer to the side of the stud wall, cracking some of the plaster and fragments of plaster are now visible in the window in the inverter...) Also, we've been trying to push things along a bit for the March 3rd deadline - the electric isn't connected yet but we have the MPAN so could have applied for the higher rate of FIT. But the company we're dealing with wouldn't apply for it - they say it's because we don't own the system yet as it isn't fully paid for (we owe~2k on a ~10.5k installation) but we think it was just because they want to have us over a barrel as they won't issue the MCS certificate 'til we've paid the balance. We don't believe in being held over a barrel, and think we've already paid quite sufficient for the work done so far so unfortunately we will have to accept the lower rate FIT. Bit of a shame, but what could we do?

 

[farmerdave]

I don't know what sort of calculations on wind loading were done - we've had precious little through from them (mainly invoices!) and I had to hunt around in the house (a new-build) to find the guide for the inverter...

 

[Gavin A]

as above, cables should be tied up to avoid them touching of at least not really moving about on the roof.

There should barely be any noise from the array even in windy conditions. Loose cables will make a rattling / tapping noise on the roof in windy conditions, and a long loose cable such as the main link cable to the array can make more of a slapping noise (I had to go back to tie one up recently that one of my teams had missed), but shouldn't really cause an actual banging noise.

I'm wondering if they've maybe put 2 rows of panels so that they're virtually touching each other and can crash against each other when they're flexing or something. Either way it needs sorting out, and can be done as they sort out the cables.

I'd also advise checking on the mounting system used if it's on slate, as I'm sure there are still companies out there just mounting the brackets on top of the slate. IMO this is potentially ok in scotland where there is Sarking board below the slate, so it is uniformly supported, but NOT in most English situations where there are lats under the slate, so the force from the bracket gets transferred directly onto the unsupported part of the slate. Worth double checking this at this stage I'd think, as sloppiness in the cables etc points to sloppiness elsewhere being likely.

 

[whinmoor]

Section 4.4.4 of the MCS PV standard says:

4.4.4 The contractor shall ensure that the roof structure is capable of withstanding the loads (static and wind loads) that will be imposed by the PV modules and their mounting arrangements. If there is any doubt, a structural engineer must be consulted. Guidance on the mechanical installation and wind loads are given in BRE Digests 495 and 489 or BS 6399.

http://www.microgenerationcertifica...ts/MIS 3002 Issue 2.1 Solar PV 2012.02.03.pdf

 

[dansk]

Also the installer is not allowed to withhold a MCS cert full stop. Payment or no Payment.

 

[Gavin A]

Also the installer is not allowed to withhold a MCS cert full stop. Payment or no Payment.

having said that though, you are required to send proof of ownership of the system with any FIT application, which usually takes the form of a receipt saying 'paid in full' on it, so the lack of an MCS cert is a bit of a moot point.

The company should however have bent over backwards to ensure that the system was fully installed and commissioned to the customers satisfaction before the deadline, or at least given written guarantees that any complaints would be dealt with promptly after the deadline and explained the urgency in making the full payment in order to be able to claim the higher FIT rate (if the gov loses in court).

Dave - I've just gone through the PV specific regs / guidance and can't actually see the bit about cables needing tying up to prevent rubbing. I'm thinking though that it almost certainly forms part of the basic 17th Edition electrical regs, which are also a requirement to be followed throughout the system, but I don't have a copy to hand... hopefully someone else will have one and can find the relevant reg for you.

 

[whinmoor]

Also the installer is not allowed to withhold a MCS cert full stop. Payment or no Payment.

Very good point. We received a circular from Gemserv Ltd (MCS Licensee) dated 28th Feb which included the following:

"Note that regardless of the circumstances, once an installation is properly commissioned according to the MCS standards, it is not permitted under the Scheme or the Code to
withhold the MCS certificate from the customer, regardless of whether they owe you money"

Your installer should have received the same and now you know it. It sounds, however, that it hasn't been "properly commissioned according to the MCS standards" so this doesn't yet apply.

 

[whinmoor]

Dave - I've just gone through the PV specific regs / guidance and can't actually see the bit about cables needing tying up to prevent rubbing. I'm thinking though that it almost certainly forms part of the basic 17th Edition electrical regs, which are also a requirement to be followed throughout the system, but I don't have a copy to hand... hopefully someone else will have one and can find the relevant reg for you.

Gavin, this is in section 4.3.2 of the draft revision so possibly not yet applicable but obviously good practice:

Cables are to be well supported, especially those cables exposed to the wind. Cables must be routed in prescribed zones or within mechanical protection. They must also be protected from sharp edges.

http://microgenerationcertification.org/admin/documents/Guide v3.8 DFC.pdf

 

[powervan]

I would say if they had started before deadline at least they should of got u on in time for the deadline! ref the cables its not always poss to cable tie EVERY cable/ connector under the pv array !! if u look up and cables are coming out below the array then yes thats (bad workmanship) but if you can see cables looping below and between panels but within the array area ie from one panel to another then i woudnt worry!! ref inverta and stuff im affraid it sounds like it was a rush job! that said speak to them with your concerns and get it sorted before you pay the £2000!!

 

[Gavin A]

Gavin, this is in section 4.3.2 of the draft revision so possibly not yet applicable but obviously good practice:

Cables are to be well supported, especially those cables exposed to the wind. Cables must be routed in prescribed zones or within mechanical protection. They must also be protected from sharp edges.

http://microgenerationcertification.org/admin/documents/Guide v3.8 DFC.pdf

ah right, I thought I'd seen it in the DTI guidance, but that was the version I've read most recently, so that makes sense.

I'm sure there's stuff in 17th edition that would apply re secure fixing of cables though, but I'm not going in to the office to get my copy today.

 

[moggy1968]

the banging may be the brackets flexing and banging on the roof, we had this from one bracket on a slate roof. The roof wasn't quite level so when the rails were on it pulled that bracket away from the roof slightly. In high wind the brackets flexed enough for that one to bang. We had to go back and had to pack under it to resolve the problem. Fortunately it could be reached from a velux!

 

[farmerdave]

I'd also advise checking on the mounting system used if it's on slate, as I'm sure there are still companies out there just mounting the brackets on top of the slate. IMO this is potentially ok in scotland where there is Sarking board below the slate, so it is uniformly supported, but NOT in most English situations where there are lats under the slate, so the force from the bracket gets transferred directly onto the unsupported part of the slate. Worth double checking this at this stage I'd think, as sloppiness in the cables etc points to sloppiness elsewhere being likely.

Thanks for all of your replies - I feel a bit more confident about complaining now!

Gavin A, I'm a bit concerned about how the panels are fixed to the roof. There's no sarking board (new build, so we know!) so presumably the brackets are just attached to the slate lats. There's a convenient velux at one end of the panels (2 rows of 8 panels) and you can wobble the nearest panel up and down quite a lot (around +/- 1cm with ease) - most of this wobble seems to be because the brackets move up and down relative to the roof, where they disappear into the lead shroud slate-replacement (sorry-not sure of terminology). The first bracket is around 70cm from the edge of the array. Does this sound normal - is this level of movement acceptable or should I be asking for more brackets?

Thanks, Dave

 

[moggy1968]

is it flex or the actual bracket moving on it's mountings? some brackets do flex a bit (slate ones we use are quite thin)
I would also never mount an inverter on a stud partition. they are very heavy and also the stud wall can act like a soundboard, making the whole thing a lot nosier.

 

[whinmoor]

Thanks for all of your replies - I feel a bit more confident about complaining now!

Yes, you do need to complain asap as the cables will take a while to wear away after years of rubbing on the slates. Sod's Law says the system will fail when your workmanship warranty has just expired and you'll end up having to fork out for repairs yourself.

 

[farmerdave]

Well, the brackets disappear up underneath the slates and are presumably nailed on underneath the lead shrouding which replaces a slate. The nailing-on point is up the roof a bit from where the brackets attach to the rails so the brackets sort of flex up and down, relative to the roof. Sorry, it's a but difficult to explain.

The inverter is attached to a board nailed between the vertical bit of the roof trusses so it's not actually mounted on a stud wall. The stud wall is in front of the inverter with a hatch cut in. Unfortunately the installers didn't bother asking us otherwise we could have had the stud moved - they just set about it with a big hammer!

 

[powervan]

what brackets have they used? i would say that sort of movement isnt good long term! i have seen a slate job where they used the threaded bar type with nut and bolts at end but these are poor for this type of install!! the bracket and fixings used is the main stay of the system if they got this wrong then i fear a few loose cables is last of your worries!!

 

[whinmoor]

Thanks for all of your replies - I feel a bit more confident about complaining now!

Gavin A, I'm a bit concerned about how the panels are fixed to the roof. There's no sarking board (new build, so we know!) so presumably the brackets are just attached to the slate lats. There's a convenient velux at one end of the panels (2 rows of 8 panels) and you can wobble the nearest panel up and down quite a lot (around +/- 1cm with ease) - most of this wobble seems to be because the brackets move up and down relative to the roof, where they disappear into the lead shroud slate-replacement (sorry-not sure of terminology). The first bracket is around 70cm from the edge of the array. Does this sound normal - is this level of movement acceptable or should I be asking for more brackets?

Thanks, Dave

70cm sounds quite a long distance. Do you mean there's no support nearer the end of the rail? How many brackets are on each rail? Can you take any photos of the mounting system as it's hard to visualise from words? Do you know what make of mounting system you have?

 

[moggy1968]

For the mounting systems we use 70cm is far too far. that would explain some of your flex. The demands on the end bracket and rail are too high, especially in an area of high wind. It's tricky because if you've got 80cm joists the last bracket will be beyond the end of the panels, but I think that would be the only option.

 

[farmerdave]

I,ll put a photo or two up shortly - I don't think I can yet as I'm a noob!

 

[whinmoor]

For the mounting systems we use 70cm is far too far. that would explain some of your flex. The demands on the end bracket and rail are too high, especially in an area of high wind. It's tricky because if you've got 80cm joists the last bracket will be beyond the end of the panels, but I think that would be the only option.

My thoughts exactly. I'd prefer to see some pictures to understand better the situation though. I'd also like to know how many brackets have been used and how close to the edge of the roof the array is situated.

 

[moggy1968]

and the spacing of the brackets

 

[Gavin A]

Well, the brackets disappear up underneath the slates and are presumably nailed on underneath the lead shrouding which replaces a slate. The nailing-on point is up the roof a bit from where the brackets attach to the rails so the brackets sort of flex up and down, relative to the roof. Sorry, it's a but difficult to explain.

actually, that sounds like they've used a reasonable mounting method from this aspect. 70cm overhang however would be more than most (virtually all) mounting rails are designed for.

 

[Earthstore]

Farmerdave, a picture tells a thousand words, so if you could post some that would be helpful, also, why not ask one of the good people on here if they are local to you, and for a small fee would be willing to come and have a look at your system and give you an expert opinion, I feel it would be money well spent for you.
There are many on here that only use good practice, and I am certain one would help you.
Sorry but you are too far from me for me to be of any assistance.
I hope this helps.

 

[farmerdave]

Ok, apologies if I'm doing things wrong here: pic 1- bit of stud wall, now sawn out, that the installers set about with a hammer.
Pic 2) view of inverter in hatch - not much room for accessing USB dock under inverter!
Pic 3) Bits of plaster, presumably these got into the inverter when the installers did 1) above?Pic 4) Cables hanging on roof - some brackets also visible.

 

[Gavin A]

I don't install Fronius inverters, but sincerely doubt that they are permitted to be installed on their side like that, as it will mean it won't be able to dispel heat in the way it's designed to.

 

[whinmoor]

I presume they didn't install the inverter on its side? How much ventilation clearance is there around it?

 

[whinmoor]

I guess he didn't rotate the photo, Gavin :teeth_smile:

 

[farmerdave]

Um yes - that is the case - it isn't sideways on! Although there isn't too much space above and below the inverter, it's in a space that extends sideways and is near a bit of roofspace that is very well ventilated.

 

[Earthstore]

Oh dear, Tell me, if you had a plumber to do work on your house would you except this standard of workmanship?
Why they have installed your inverter in that position is beyond me, now you have a large hole in your stud wall, also cooling may be a problem.

 

[powervan]

inverta would be nice to have plenty of room around it but not always poss! i presume door and frame going over it so its not that bad! dust i presume is just behind cover so could be cleaned! cables well ive seen worse! your issue is distance of brackets i think! all other probs easily corrected!! still big shame u missed deadline!!

 

[whinmoor]

Well, we generally leave something like 25cm clearance on all sides around our inverters. I expect (but don’t know for sure) that Fronius expect something similar. Maybe someone can confirm?
That plaster or sawdust or whatever isn’t very attractive. Add to the list of complaints.
Difficult to see much on the roof except the cables shouldn’t be resting on the slates like that. I can see 5, maybe 6 brackets on the right (bottom?) rail which probably isn’t enough for 8 panels in a windy area.
In summary, it’s looking like a pretty shoddy job.

 

[Gavin A]

I guess he didn't rotate the photo, Gavin :teeth_smile:

oh erm yeah I suppose that's fairly obvious now I look at it again.

 

[farmerdave]

Thanks for all of your comments. I'll go back and try to measure bracket spacings and have drafted an email detailing the shortcomings to the company concerned. I'll get back to you with their response!

The house isn't finished yet - the hole in the wall will be made into a nice hatch with a door on it - fortunately we have an excellent joiner!

 

[farmerdave]

Right oh,
I've had a measure, and for those that like hard facts (sorry, should prob have put this in the op):

We have a 16 panel array, 2 rows of 8 panels
Panels are 1640 x 992 mm ET Polycrystaline
They're mounted on 4 rails (2 per row)
Each rail appears to be attached to the roof by 7 brackets (28 brackets in total)
I can get to one end of the lower row via a handy velux:
Its around 0.7m from the edge of the row to the first bracket
Brackets appear to be 1.2m apart.

How does that sound in an exposed location in the far N of England?

The brackets being around 1.2m apart suggests they might be joist-mounted, rather than being attached to slate lats, but I'll ask the supplier the question.

There is a bit of knocking in moderate winds, but what that's due to I have no idea (maybe brackets on roof or slate, maybe row to row banging). It's the problem of the supplier to sort out - I'll bring it to their attention.

Thanks, Dave

 

[dansk]

Very good point. We received a circular from Gemserv Ltd (MCS Licensee) dated 28th Feb which included the following:

"Note that regardless of the circumstances, once an installation is properly commissioned according to the MCS standards, it is not permitted under the Scheme or the Code to
withhold the MCS certificate from the customer, regardless of whether they owe you money"

Your installer should have received the same and now you know it. It sounds, however, that it hasn't been "properly commissioned according to the MCS standards" so this doesn't yet apply.

;-) knew i had seen it recently, but couldnt ref it.

@Gavin Yes fair point.

 

[moggy1968]

It's a pretty shabby job to be honest!!
You don't just bash holes with a hammer in a plasterborad wall, you use a saw.

The Fronius IGTL inverter requires 200mm free space on either side for the cool air vent to the left and warm air outlet to the right. It should be mounted on a 'stable vertical wall'
Also, where it is installed in closed environment, as your intending it is 'necessary to make sure that the hot air that develops will be discharged by forced ventilation'
I would take that to mean a fan. Thats straight out of the Fronius manual, which your installer should have left with you.

Aditionally your array should be earthed. It is a transformerless inverter and the array can be touched from a velux window. You should be able to see a green and yellow 10mm earth running from the rails to either the main earth or a spike in the ground, depending on your supply earthing type.

We would fix brackets at 1200mm intervals on a bungalow down here in the south. Where you are I would say that is inadequate, but I haven't done the calcs for your area, maybe a northern installer can advise on that.

If your installer unlawfully witheld your cert, as suggested above, then I would suggest you would have a case against them for any resulting losses.

 

[powervan]

Ventilation via fan!! well they defo put in wrong place if its small space surrounded with celotex! ref brackets i BELIEVE 400mm from end of rail is MAX!!