Very odd SE string issue

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RATA1

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Hi guys,

First post as I am looking for ideas about where an issue could be with my solar system.

I have a SE system with 18 panels, 4xE, 4xS and 10xW all connected in one string.

My issue is that one of the optimisers on the west is reporting it is "ready" ( floats around 0.5 to 0.8v) almost an hour before the east and south are even interested (way before sunrise). Eventually the east and south optimisers come on line when the sun is up or there is enough light and then the inverter struggles to come out of night mode because of this optimiser on the west (I assume). Its behaviour is that the voltage increases as light increases, comes out of night mode then the voltage is dragged down and then it goes back into night mode. Then it starts this all over again - in and out of night mode! When it is really sunny the issue is far worse going in and out of night mode for sometimes an hour!

I have had the optimiser replaced and the issue is exactly the same. Have any of you guys seen this or have any ideas what it could be? I have logged it with SE and they have changed the startup voltage to a lower value and the system starts up a bit quicker than an hour when it is sunny but the issue persists.

It is driving me nuts as there is a fault that needs to be found. It is rather strange as once the system is up it appears to be fine on this and all other optimisers. I suppose it could be an optimiser either before or after this one that is reporting itself ready, the inverter or a cable or connector but before I take to the roof - any ideas? 

I hope to isolate the west panels from the east and south to see if it is indeed on the west as this is an easy connector unplug.

Thanks.

 
sounds like it isn't communicating properly with the inverter. In theory 1 unit should not stop the others from working....it's the whole point of using optimisers. I would try wiping the system and starting again. It should be quite easy to disconnect the duff optimisers (turn DC off first). Might be worth wiping the system and starting again? The only other thing that springs to mind is a dodgy connection between panel and optimiser.

Don't think you will get much help here, not many people use SE, including me - I've fitted lots of solar systems, but have only used this stuff twice as I'm not a fan of fitting potential failure points on a roof. Your best bet is to persist with annoying the technical helpline. Please do post any solutions / findings on here, even if we can't be much help.

 
Hello,

Thanks for the reply.

Inverter factory reset has crossed my mind. Not sure if I would lose my updated F/W that SE have put on trying to fix the issue. I would certainly lose the config changes they have made. A last resort i think at this stage.

I will swap the panel to an adjacent one with a few MC4 fly leads to see if the fault moves as roof access is pretty easy as I have a tower. If the fault stays then it (logically) can't be the panel or the optimiser (as this is a new one) but most likely the connections or the inverter. If the fault moves it is the panel or its connectors.

I will post my results.

 
I was thinking more along the lines of wiping the optimisers from the system and re-installing them. Not sure how you do that as I don't play with SE very often. Within in the menu on the inverter there should be a string analysis screen, so if there's a fault is reads a percentage eg 50% means halfway along the string. I've used this to find earth fault leakage before. Might be useful? 

 
Evening. Thanks for that, I will take a look. 

I did have a thought though - as my optimisers are not installed on a metal racking I don't have an "equipment ground" - could this be the cause of this issue if they aren't bonded together or is it just a safely bond that isn't required (being a transformer-less inverter)? Just I have seen some weird issues with comm's kit in the past that isn't referenced to the same 0v before.

Just a late night thought..

 
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