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

Solarchaser

Yeah the male and female are marked as pos and neg on most connectors as per the photo QrizB put up earlier, and from memory it's male and female are different from what you expect, generally you would expect the female to have the larger tube and the male to have smaller to fit inside, but I'm sure it's the other way round, which can wrong foot you. 
The id is subtle and could be clearer, but I'd suggest it's deliberately done this way because the solar industry does not want folks like us replacing these parts, only "qualified" installers.

I've have also come across the e031 fault a few times now, and yeah, you definitely need a good bit of heat, for me, I had to use a solder sucker to get it from both sides and only after I had removed most of the old solder using braid as usual, then refilling with new solder to get the Flux into it, and then sucking it.
The tracks are poor, and common to lift, I used a couple of legs from resistors or leds I had to repair the tracks after rubbing back what was left with a fibre pen, it's a lot longer process than you expect when you sit down to it, so honestly,  I feel your pain.

ThisIsWeird

Solarchaser said:

Yeah the male and female are marked as pos and neg on most connectors as per the photo QrizB put up earlier, and from memory it's male and female are different from what you expect, generally you would expect the female to have the larger tube and the male to have smaller to fit inside, but I'm sure it's the other way round, which can wrong foot you. 
The id is subtle and could be clearer, but I'd suggest it's deliberately done this way because the solar industry does not want folks like us replacing these parts, only "qualified" installers.

I've have also come across the e031 fault a few times now, and yeah, you definitely need a good bit of heat, for me, I had to use a solder sucker to get it from both sides and only after I had removed most of the old solder using braid as usual, then refilling with new solder to get the Flux into it, and then sucking it.
The tracks are poor, and common to lift, I used a couple of legs from resistors or leds I had to repair the tracks after rubbing back what was left with a fibre pen, it's a lot longer process than you expect when you sit down to it, so honestly,  I feel your pain.

Thanks again.

Yes, I missed that detail from QrizB's earlier post - thanks QrizB :-)

Yup, I did a lot of 'sucking' of solder too, and used braid afterwards, but it still left a lot of solder coating the pins which needs significant heat (but not too much!) to heat through to the other side. If I was to do this again, I think I'd break up the relays in situ, and then withdraw each pin individually!

But, wow, the damage around the failed pin was something - the pin itself was completely missing, and it had arced a sizeable hole around where it went through the PCB.

Cool - looking forward to doing the panels :-) (But then, I had been looking forward to doing the relays :-)  )

ThisIsWeird

Any difference in quality in MC4s? Are the ones in this kit the same quality as any other, do you know?

https://www.ebay.co.uk/itm/155688120402?

Thanks.

Edit: Bought!

ThisIsWeird

On a literally connected note (fnurrrrrr) I'm thinking that the best thing to do when replacing the external cables could be to join the new cable using non-disconnecting connectors closer to the panel, so as to not have any more-vulnerable openable connectors outside. Then fit the MC4s immediately inside the roof where there's good access.

Are there such 'fixed' connectors for PV cables, do you know? Thanks.

Solarchaser

I'd imagine your relay would have dried up its solder, then started small arcing, then larger and larger arcing, each time creating more heat in the pcb, eventually weakening the area around the tube and the track itself, I'm assuming that's why it came away so easily.

As far as permanent connection goes im not aware of anything like that, or that's to say I'm not aware of a cheap solution that would offer better protection than mc4's.

I mean, you could crimp them together, solder them together etc etc and then fit shrink wrap on top, but really I think the mc4 is a better solution, rubber seals made for outdoor use

Generally there should be enough length on each panel lead to join to the next, and so when the daisy chaining is done, id have one lead on each side coming into the property with the last connection being to the last panel rather than the connector to another connector on your pics.

ThisIsWeird

Thanks again, Solarchaser.

My plan is to remove all the panels, noting and labelling the wiring for each. Once down, I'll cut off the existing connectors that are on them, and crimp on new MC4s - the correct ways around. I'll replace all the external wiring, making up new cables, but colour-coded this time in black and red to reduce mis-wiring risk. (I notice that some the existing black cables have brown tape flags on them!)

After the daisy-chaining (not sure how the existing is done at the moment), the new cables will be brought inside via the neat lead flashings around the brackets as now, and will then be connected to the existing indoor cables with suitable connectors at a convenient spot - using MC4s or possibly Wagos?

A couple of Qs, please - I don't know if the existing cables are 4 or 6mm2. There are two arrays of 8 x 200W panels each. Can I tell from the outer double-insulated cable diameter?

And, once the cables are safely inside, will Wago connectors be ok (dry garage), or am I best to also use MC4s there?

Ta

ThisIsWeird

Mystery solved.

The Suntechs come with 'Radox Solar Connectors' attached, and - having began to remove the bottom row of panels - I see that only the very end panels have also had the MC4s fitted. All the rest simply daisy-chain together. So, not completely daft install!

The other goods news for me is that I'll only need to remove the bottom row, as this then allows good access to the wires in the top row as they were fitted 'upside-down' with their JB's at 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?

ThisIsWeird

ThisIsWeird said:

Any difference in quality in MC4s? Are the ones in this kit the same quality as any other, do you know?

https://www.ebay.co.uk/itm/155688120402?

Thanks.

Edit: Bought!

Nice kit - the crimping tool leaves nothing to be desired, so I'm assuming all the other bits - MC4s are also good.

The MC4s are marked 'TÜV' make, so that's positive too, assuming they aren't rip-offs.

What standards should I be looking for with the 4mm cable?

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.

QrizB

ThisIsWeird said:

What standards should I be looking for with the 4mm cable?

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?

I think I quoted some cable standards earlier in this thread?

As for testing panels, do you know what the spec of the panels is? This should include Voc (open circuit voltage) and Isc (short circuit current) both of which are fairly easy to check provided you have a suitable meter and are careful (50 volts is usually safe, but try to keep everything dry and don't test more than one panel at a time).

Voc only varies slightly with the intensity of the sun but Isc is heavily dependent. I tend to use Isc to check thqt panels are similar, rather than as an absolute test of performance.

ThisIsWeird

QrizB - oops, sorry, you did. Thank you.

Isc - it's ok to short the panel? No resistance load? I guess only for long enough to take a reading?

My meter reads to 10A - I'll check the panel spec.

Thanks again :-)