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