Best PV panel cables and connectors to use for replacing existing?

Hi again.

Following my recent zero-Riso issue (unresolved) and also because my system has, in any case, been prone for a good while to the odd 'Low Riso' fault following heavy rain and high winds, I'm going to begin by replacing all the cables and connectors going to my panels. It should be a physically straight-forward task as the panels are on a garage roof, and there's a wide stone wall alongside it from where I can directly prop a roof ladder.

I also know about the considerations over generated voltages.

My Q is, which are the best cables to use for the replacements, and which are the most reliable connectors to use? And where do I source these?

Many thanks.

No one?!
The existing panels have two plugs on them in quick succession - any idea why? Thanks.

It's not very clear in the photo whether the far connectors are the same type. If they're not, the short intermediate cable may be an adapter from one connector type to another. I'm imagining installers don't want to be faffing about making up cables, but just use ready assembled?
PS I know zero about solar panels and their wiring, so afraid I can't help

Is that acceptable practice in the PV industry? Cables and connectors just lying on the slates of the roof.

brianmoooore said:

Is that acceptable practice in the PV industry? Cables and connectors just lying on the slates of the roof.

Click to expand...

I wondered that as well. Looks very amateur, and they must get a lot of abrasion when they move around. I've seen tv coax cables which have been draped across roofs and got damaged due to wear.

Thanks all.

Mystery solved.

The Suntechs came with 'Radox Solar Connectors' attached, and - having began to remove the bottom row of panels - I see that only the two end panels have also had the MC4s fitted on the cables that head off to the inverter. All the rest simply daisy-chain together using the Radoxes. So, not a completely daft install!

The other goods news for me is that I'll only need to remove the bottom row of panels, as this then allows good access to the wires in the top row as they were fitted 'upside-down' with their JB's towards the bottom. So I'll snip off all the old Radoxes and fit MC4s in situ for these, and do the lower row on the ground. I have a tub of silicone grease, too, to wipe over all the rubber seals before assembly.

A Q - I think I've seen MC4s with double-O-rings? Anyone know? Are there better quality ones out there? Thanks.

I bought a MC4 kit, and it all seems very good - crimping the tool is certainly high quality. The MC4s also seem good quality, and are marked 'TÜV' make, which is reputable - assuming they aren't rip-offs.

When it comes to new cable and MC4s, what standards should I be looking for?

And, any layman's tests I can carry out on the removed panels? Lying flat on a cloudy day, they chuck out around 50V, but I know that's not under any load. But is that worth checking - that they are all pretty consistent? Any other checks, apart from visual?
Thanks.

Shooby said:

I bought a MC4 kit, and it all seems very good - crimping the tool is certainly high quality. The MC4s also seem good quality, and are marked 'TÜV' make, which is reputable - assuming they aren't rip-offs.

When it comes to new cable and MC4s, what standards should I be looking for?

And, any layman's tests I can carry out on the removed panels? Lying flat on a cloudy day, they chuck out around 50V, but I know that's not under any load. But is that worth checking - that they are all pretty consistent? Any other checks, apart from visual?
Thanks.

Click to expand...

I've hopefully answered some of my own Qs.
Turns out I don't need any new cable as the existing is in perfect condition - no abrasions at all. I'm cutting the panel cables shorter as I replace the connectors with MC4s, and that should reduce future drapes.
Is it ok to 'short' the panels using an ammeter to take a quick reading?

Shooby said:

I've hopefully answered some of my own Qs.
Turns out I don't need any new cable as the existing is in perfect condition - no abrasions at all. I'm cutting the panel cables shorter as I replace the connectors with MC4s, and that should reduce future drapes.
Is it ok to 'short' the panels using an ammeter to take a quick reading?

Click to expand...

Again, answering masel'.
Isc is 5.62A, which I presume is max, in full sunshine? And it's ok to insert an ammeter between the panel terminals, I've been told - ie it's happy with a 'short'.

All panels giving 40+ open circuit volts, and 5+Amps in sunshine, with the last two tested showing 3+Amps as the sun dropped in the evening. Nice fat sparks.

All connectors replaced with MC4s, and all cables are completely free from damage or even light scuffs. Connected up, 300+V showing at the inverter, fire her up, and Aurora claims 0Meg Riso...

I am as certain as I can be that the array is absolutely fine. What else can cause this sort of fault? I've long suspected it wasn't the arrays, as they BOTH returned 0M Riso readings at the same time when connected independently, when this fault first started! I only went to the effort of checking the cables and replacing the connectors as a fault 'elimination' move, and I am confident as I can be that this side has been eliminated.

Thanks.

Update: Incredibly, it appears that BOTH my own Aurora inverter, on which I'd carried out a E031 repair, only to find this 0.00M Riso error on reinstallation, AND the professionally-repaired replacement BOTH had the same new Riso fault! The latter occurred a couple of minutes after having been successfully running.

I checked and re-plugged half my array (it's dual) to see if there was anything amiss up there, and these gave secure readings. But still 'zero' ohm Riso on both arrays.

Yesterday, I took delivery of an unused (but stored for a few years) Aurora replacement (actually an ABB make), and this is now working perfectly - 20.00Mohm Riso, with not even one mA 'leakage'.

So, incredibly, both my old and the repaired replacement inverters had developed the same internal Riso fault.

Does anyone have any idea what could cause this? The replacement inverter did work for a few minutes before going audibly 'pffft', tripping the RCD, and then returning '0.00M' Riso figures on rebooting, so I am assuming that something - a capacitor most likely - has blown inside the device. The 'restored' inverter is going back to the refurbishers, but I'll have a close internal inspection of my own original one, see if I find summat amiss.

Any ideas what to look for?

What a stupidly-great feeling to have PV generation restored tho!