Solar PV Hints, Tips & Troubleshooting

I very much doubt it. I'd reseat the connections on the inverter, then work towards the panels.

You'd expect the string itself to be fine, so it can only be the cable to the first or the cable from the last

How do I change the wifi connection for the solarman app? Recently got new internet.

Hey, could I get a steer on this please? It’s installers challenge to sort right now as haven’t paid fully yet. Do I have (at least) the dreaded issue that a string can’t start when it’s a low voltage with low number of panels? Looking to get a steer to challenge options they suggest to fix.

Background: PV is live 2 weeks and looks like the South roof (and West but more on that later) isn't outputting what I’d expect relative to our East and others Boardsie’s here. And I’m trying to find why. South only 4% better than E (average kwh per panel since install). So what’s below might help that or not. Am looking to make sure we eek out the most to reduce our payback years.

Q1 on South under performing: So if the voltage is 0 on a string, I assume it means it can't produce? Am seeing that on the S one. I’ve no idea if they are in parallel or series. Installer did setup, not a DIY job. 3 x 305w panels on South on it’s own string (all roof can fit and they planned to fit more until realised on install day). Then 4 on West into own string. It's a huawei inverter. No optimisers on S or W roof in case that matters. Have 2nd inverter with a single string of 9 on East and that output is flying – so no changes needed there. We don’t have any other space to add more panels – everywhere is full (roof, and no garden space / shed…).

To my very noob eye it looks like the South string (green line in pic) tries to ‘wake’ at 6am, and hits ~100v and can’t sustain that and drops to zero. Then goes back to sleep. Hours later (8am) it somehow kicks in and stays ‘alive’ and starts to produce. But then drops to 0 voltage earlier than West too. I won’t pretend to know any of this bar what I’ve read. And the West (blue line) looks fine all day voltage wise.

Stats wise I use fusionsolar.huawei.com (only access to PV system I have) and am somewhat limited in what I can see. But I can run reports for kwh per string by dates to can see overall output in places – just not easily in 1 report.

What’s below is from yesterday, but it’s the same every day (S starts up and ends earlier voltage wise). Yesterday was a blue sky day for most part. Same graph on the worst day where couldn’t see the sun. So weather doesn’t seem to change it. 

Q2:West is poor output too. So will ask them to look when they are changing anything on S (didn't flag that to them yet, only spotted it's bigger than I though today when checking stats). West only has 4 panels and that’s the lowest output on average I have per panel (across S, E and W). I did read that inverters (Huawei at least) like more panels per string as more efficient. So is having 3 S panels on one string and 4 on W also dragging down output? W is 23.5% lower than E (granted E has optimsers on half which give a performance boost it seems – don’t have much data for that as yet, but seems to be the case). But that huge % difference between E + W. Others see anything like that? And any ideas how to improve that?

Thanks for any help finding the areas to change fully or tune.

Thanks for that. Appreciate the steer. Could you help me make sense of the numbers please?

Panel says VOC is 40.8v. Panel also says says Vmp 32.5V.

And seems to vary from 89V to 103V on the string when its running during the day. Which is around 3 times the 32.5 number above. Does VOC or Vmp have to hit the startup / min DC voltage per mppt? Won't pretend to know.

Startup / min DC voltage per mppt on inverter looks like 100V. Screenshot below. Not sure I'm reading the right number. It's the only reference to 'startup voltage' in the doc. Or only word 'startup' relating to voltage.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://support.huawei.com/view/PdfRead/EDOC1100136173/SUPE_DOC/6001/document.pdf&ved=2ahUKEwidlJS8k7j5AhXUSsAKHWnABg0QFnoECBIQAQ&usg=AOvVaw2KOCgKzdbR-xkSBKz-9k2w

Mine is 3KTL model.

So what all that means is.... basically it can't easily get to 100V so takes much longer to get going. That right?

How come later in the morning it does hit the min startup voltage so it can fire up? Then it runs for the day. But also goes 'to bed' early too. Does heat or something else make voltage rise so it gets enough to start?

Can't fit any more on roof unfortunately so no options to move stuff around.

Ta for help

Thanks for that. Am gonna see what they suggest now I have some options. As you say could be optimisers and join the West and South. Need optimisers on every panel?

Or microinverters for South as you say.

Not gonna ditch the 1kwp on South. Makes a difference on a small maxed out roof. And panels are there already. Would kill me to take them down again :)

Anyways....they can mull over the options.

Post a pic of all 4 from distance. Are you paralleling them or in a string ?

parallel is the goal but i currently only have 2 mounted, the other 2 are just unmounted until i figure out the problem.

2 are on my van conversion, 2 are just moved about for testing.

I’m fairly sure I asked about this during my install and I was told €1500. Maybe he just didn’t want to do it. I think I would have gone for it for €400

Correct, all other panels are fully disconnected, and each panel is checked without anything else connected to it (no other panels)