Generally, MC 4 connectors from  reputable makes (Stäubli come to mind, there are many other makes) have an environmental rating of IP67 but only when the correct cable diameter is used and the glands are done up as per the instructions. This means they are then fine for short periods of immersion. However,  generally cables and connectors left in the sun and the wind and the rain, will not last as long as the same part under some sort of shelter, even if it is just tucked under the panel, and I'd certainly expect things to be neatly tied up and not flapping about in the open or able to be trodden on or tripped over.

Apart from mis- assembly , as alluded above, the other problem  is if they have been mated while damp, as then that sealing works against you and the ingredients for corrosion are sealed in, instead of out.

What sort of problems are you seeing - it is quite possible that the connectors are not the real problem, but rather like seeing mismatched screw heads on door handles can be a flag to check the rest of the woodwork, a sloppy approach to what you can see, may indicate the same (lack of) attention to detail in other areas less obvious.

Mike.

mapj1 said:

If there are joints sitting under that day after day, I'd be looking to lift them up out of it, though if the cable is unbroken it should be fine

Unless I'm much mistaken, looking at that last photo, several of the connectors have been laid on top of buckets!  I'm not sure which section of BS7671 that corresponds to 

not sure which section of BS7671 that corresponds to

133.5 ?

  - Andy.

Hi Andy 

To be honest, all panels stops functioning when the full sun hits and works partially in the winter. 

We are not meeting the targets set by the Council. 

Thanks,

Kiran

Hi Mike, 

The cables are in pond of water. We noticed that when we were able to get on the roof. 
We also have roof leaking due to various ponding related issues. 

It is a string inverters 2 sets connected by 17 panels X 2 = 34  on each roof with 250W panels. We are not seeing any benefit as the cables/inverter picking up many issues. 

I might have to look at NHBC warranty but only if the installation and design is not appropriate to the standards. 

This was lifted off the ponding water by an electrician who resides in the community. Basically that is when we realized cables submerged. 

That roof top weed pond reminds me why truly flat roofs are not supposed to exist according to building control.

Apparently some are .. I recall something on the TV where the (German?) installers had deliberately installed the deck level with upstands on the outlets -  the idea being to trap a layer of water on the roof to act as a UV barrier to protect the membrane ...  it does require an extraordinarily good seal on things though. I suspect that's wasn't the intention in this case however.

   - Andy.

To be honest, all panels stops functioning when the full sun hits and works partially in the winter. 

Definitely something very wrong there then. But hard to tell from this distance what the cause might be - could be insulation faults on the d.c. side or an undersized inverter shutting down when it's overloaded, or any one of a dozen possibilities.

   - Andy.

panels stops functioning when the full sun hits and works partially in the winter. 

I will suggest  that alone is a good enough reason to get the installers back to explain themselves.

The electronics will hopefully produce a log of error codes that can be read to work out why in more detail, but that may need kit you do not have.

At the risk of the first class idiot question, with respect to the panel tilt, which way is south?

Mike

having realised purpose of the buckets, connectors are not designed for that sort of long term immersion. Cable basket on some more of those concrete blocks may be worth considering,  (https://www.tlc-direct.co.uk/Technical/DataSheets/Univolt/Univolt_PVC_Tray_Guide.pdf )but ideally the roof needs to slope towards an unblocked drain!!

I can confirm that upstands on the outlets are not sealed properly. 

KIRAN.M said:

To be honest, all panels stops functioning when the full sun hits and works partially in the winter.

You need someone who can check the error logs on the inverter(s).

My suspicion is an over-voltage trip on the AC side.  If the wiring is under-sized or too long anywhere between the inverter and the local transformer, it can pull the local voltage so high that the inverter shuts down.

You do realise that if you're going to repair the roof, then you're going to have to take all the panels off? Maybe that would be a good time to tidy up the wiring.

KIRAN.M said:

To be honest, all panels stops functioning when the full sun hits and works partially in the winter.

You need someone who can check the error logs on the inverter(s).

My suspicion is an over-voltage trip on the AC side.  If the wiring is under-sized or too long anywhere between the inverter and the local transformer, it can pull the local voltage so high that the inverter shuts down.

You do realise that if you're going to repair the roof, then you're going to have to take all the panels off? Maybe that would be a good time to tidy up the wiring.

And if that is the case, the over-voltage trip level is something that within limits can be adjusted by the installer, as a software parameter.

I agree Simon and that is the best case. Hoping for NHBC to approve that. They are looking into the roof situation. 

And they asked us under what wiring regulations and standards that the panels does not meet the standards? I came across BS 7671 but I do not have the technical knowledge. I was told this is the best place to get some clarity. 

And I was told because of the installation and orientation, a wrong inverter was installed. It is Afore string inverter 10KW but the panels are set for 8 KW

inverter 10KW but the panels are set for 8 KW

That doesn't sound disastrous. The larger the inverter the greater the losses (as an absolute figure) so it's common to size the inverter to the peak rating of the panels, or even a little less(!) (my system has 2.14kWp of panels but only a 2kW inverter)  - but inverters still work perfectly well with reduced output from the panels (as happens 90+%of the time anyway as the sky isn't perfectly clear or the sun isn't at its zenith) - so 8kW of panels feeding a 10kW inverter should still work reasonably well - even if the losses a little higher than the ideal and so the final output is a percent or two lower.

   - Andy.

And they asked us under what wiring regulations and standards that the panels does not meet the standards?

It's going to difficult to prove a defect that way I think. BS 7671 isn't a "thou shall do exactly this to comply" sort of document - rather it talks in general terms of things needing to be adequate for the circumstances. I can see the PV installers (if they were still about) taking the view that if the roof itself had been correctly built, there wouldn't have been any standing water and so both the connectors and the cables would be perfectly adequate, at least from a water ingress point of view. Routing and/or trip hazard is even more vague in BS 7671 - laying cables unclipped on a suitable surface where they're unlikely to be disturbed is certainly recognised as OK - whether your roof classes as "unlikely to be disturbed" is probably a matter of engineering judgement and the exact circumstances. Best practice, adequate, just-about-comply aren't always the same thing. Costs always come into play too - many customers given a choice between a state of the art cable management system or a sign on the access door that says no unauthorized access and a work policy that says all other trades when on the roof need to stay clear of the PV installation, will pick the less costly option. Ideally designers/installers should discuss all these sort of details with the end customer, but I suspect that most of the time they'll just assume that what they did on the previous jobs will likely be acceptable.

   - Andy.

Thank you Andy for sharing your perspective. I appreciate that BS 7671 allows for some flexibility in interpretation, we are currently facing a -45% performance shortfall, which suggests a significant issue that goes beyond just compliance considerations.

1. Limited Roof Access – The flat roofs in question are only accessible via skylight AOVs, meaning they are not routinely accessed or disturbed. This makes it unlikely that external factors have contributed to the current state of the installation.

2. Lack of Verification – Unfortunately, no one had the opportunity to review the finished installation to confirm its condition or functionality at the time of completion. As a result, there is uncertainty about whether the system was installed to an adequate standard and performing as expected from the outset.

3. Compliance Obligations – This system was a compulsory requirement to meet the council’s emissions targets. Given the current shortfall, the responsibility now falls on the management company to rectify the issue, which is a considerable concern.

Rather than just assessing whether the original installation met the minimum technical requirements, the key question is whether it was fit for purpose and capable of delivering the required performance. Our priority is to understand the cause of the shortfall—whether due to design, installation, or another factor—and explore a resolution that ensures compliance without placing undue burden on the management company.

I would greatly appreciate your thoughts on how best to move forward in addressing this issue.

Lack of Verification – Unfortunately, no one had the opportunity to review the finished installation to confirm its condition or functionality at the time of completion. As a result, there is uncertainty about whether the system was installed to an adequate standard and performing as expected from the outset.

Do you have any historical meter readings? Ideally PV generator meter which should tell you directly what the output was - so that could be compared with other systems for the same periods to compensate for weather variations (but I'm not sure they're always installed in these post-feed-in-tariff days), failing that ordinary import/export readings might provide some clues - e.g. did consumption drop noticeably when the PV system was commissioned? and/or do the import/export figures vary more than can be accounted for by the seasons?

   - Andy.

Yes I do. We are reaching almost 8 years. According to MCS data, annually we should be generating approx just over 31K Kwh. We have cumulatively only achieved 125K in all these years. Our FIT was never setup nor registered too. And we have only exported less than1000 Kwh..

So what do you think about performance? Thanks Andy.

“And if that is the case, the over-voltage trip level is something that within limits can be adjusted by the installer, as a software parameter.”

Yes in theory. Except that in most cases on this scale the OV protection is pre-set for G59/G99. Technically changeable in many (but not all) cases but only with DNO’s permission which would likely mean an additional relay closer to the point of supply. 

KIRAN.M said:

-45% performance shortfall

Is this against the installer’s estimate (which method did they use?) or a simplified building performance / EPC calculation (eg SAP)? You describe a flat roof with multiple orientations on a single inverter with considerable shading… if the calculation doesn’t take the detail into account (eg PVSyst or PVSol or similar modelling) it could be that the performance has been oversold rather than the system underperforming.

Although with the shutdowns you mention it could be both!