Solar Edge P404 optimiser issue

[nowty]

I've just scanned datasheets for both panels, they look so similar, I cannot imagine a compatibility problem.

300W 10 x 6
https://www.q-cells.co.uk/uploads/tx_ab ... v01_EN.pdf

315W 20 x 6
https://www.pluginsolar.co.uk/wp-conten ... heet-3.pdf

If you look in the detail, the 315 says 6 x 20 (120), but the 305 says 6 x 10 (60). The P404 optimiser is “only” 60 & 72 compatible- so I suspect that the 120 config of the 315 is the issue. There’s also a 120 version of the 305, these versions are marketed as DUO.

It’s raining today, sunny tomorrow hopefully . Luckily my mate is coming round with his ladder

The 120 cell ones are simply 2 half sized panels in parallel, so they give the similar voltage and current as the full 60 cell ones. But if its always underperformed, there might have always been something wrong with it.

And looks like we will go to 4 x quarter sized cells in the near future.
https://www.solarpowerworldonline.com/2 ... ber%20said.

[Lincs Robert]

Ok an update.

Firstly, I’ll be busy for the next couple of weeks so there will be zero progress on this & will explain why I’ve gone quiet.

I’ve also had a sensible conversation with someone at SE. He assures me that the duo panels are compatible. On closer inspection it seems that the other 2 panels I had on the roof at the same time as this one are also 315 Duos - and are working well. I’ve also spoken again to the owner of the solar company I use and they are going to loan me Duo 335 & 345 panels to try and get to the bottom of this mystery. Now that I have the 315 Duo off the roof I’ll ground mount all 3 and do some tests in a couple of weeks.

So, as I think young people say, laters

Rob

[Lincs Robert]

Ok, so an update as I think I’ve solved the problem. I was lucky in that my supplier has given me a couple of leftover panels to help with the fault-finding. It was all quite time consuming and luckily yesterday was fairly sunny and not too windy - which all helps.

By a process of elimination and logical deduction I firstly established that all the panels were ok. Next, onto suspect optimisers - again I had a spare one to help. Lots of swapping, pairing - I’ve been up & down into my loft more in the past 24 hours than ever!

It turns out that it was actually a faulty MC4 connection. It was on the connection with the short wires from the optimiser to the panel, so it was a Solar Edge mating with QCell connector. The connector hadn’t locked and was sitting proud of being in by a good 5mm. It was quite tight, so I suspect whoever had mated it did the usual of pulling to see if it was a good fit, which it was, and then left it without a full visual inspection. It had been in place like this for about 2 years. I suspect that a combination of reduced contact area and possible susceptibility to the ingress of water all combined to make a poor quality connection - which under higher loads then caused the issue I was getting. As it was on the panel side of the optimiser that would explain why the optimiser looked “ok” and was visible to the monitoring system.

The resolution was that I replaced both the male & female connections as whichever one was “at fault” would have caused the other to deteriorate as well over time.

All I need to do now is keep an eye on it and then negotiate with my supplier to keep the 2 panels he loaned me - I’m sure I can find somewhere to put them.

It’s interesting that apart from all the running around, the fix was fairly straightforward and made so much easier by the panels in question being mounted on a pergola, with the optimisers underneath & accessible. It would have been a whole world of pain if they’d been up on the main roof.

I like an outcome and reason WHY something happened the way it did.



Rob

[Countrypaul]

Connector issues do seem to be the most common cause of the problems you described, which is why it was the first thing I asked. Unfortunately as you have obviously found, not always that easy to find when they aren't right.

Well done for finding the problem and fixing it.

[spread-tee]

I wonder if a thermal imaging camera would have spotted it?

Electricals and plumbing both suffer unreliability mainly due to the onsite bits of the construction, but as you say not always easy to find.

Good to get a reason though.

Desp

[nowty]

Its very satisfying when you get to the bottom of a problem which makes no sense.