You should certainly have one string all the way to the left so only one gets the worst of the shading but the output number does suggest something is terribly wrong. It needs to be checked to ensure a connector has not popped and one string is down thus leaving a shaded string? Hard to say. You could turn off one string and see if the output changes?
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low output until all panels in sun
Discuss low output until all panels in sun in the Solar PV Forum | Solar Panels Forum area at ElectriciansForums.net
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It may all be on one string.
If it is one string then it is right on the voltage limit of the inverter and if the temperature is low it will likely exceed the limit as these panels are 37voc at STC. Maybe something to do with it. So how many inputs are there from the panels? 2 cables or 4 cables?
- Reaction score
- 723
The output figure of 0.37kW does seem low to be honest.
I would be amazed if the panels at the right end of the array were actually providing any benefit whatsoever. A proper shading analysis would have pointed out which panels would receive significant shading - something, incidentally, that the new MCS method won't do.
I've not got time to check the system parameters but I will when I get back home.
I would be amazed if the panels at the right end of the array were actually providing any benefit whatsoever. A proper shading analysis would have pointed out which panels would receive significant shading - something, incidentally, that the new MCS method won't do.
I've not got time to check the system parameters but I will when I get back home.
OP
davey_b
I'll need to check by looking at the inverter but I'm pretty sure there are 4 inputs from the panels to it.
OP
davey_b
It's this one here: SolarMax S series | SolarMax
If you want a photo of it in situ I can do that though.
If you want a photo of it in situ I can do that though.
you've been sold the wrong inverter. For a string inverter in shading like this you need either Aurora Power-One, or SMA TL or HF inverters, or similar which have a full voltage range scan function that stops it sitting on a false peak like yours is, and enables the bypass diodes to function correctly to bypass the shaded sections and allow the rest of the array to operate at near enough full capacity.
they have also probably undersized the cable, causing the inverter to raise the local grid voltage beyond the protection limits causing it to cut out - either that or you have very high grid impedance on your incoming supply / high grid voltage anyway, or maybe a lot of other solar installs on the same line.
I'll post up a graph of a system we've been monitoring that has hard shading coming across it from 5.30pm, without this function enabled it was doing as yours is, with it enabled it's reducing output by around 10-20% as the shading runs across the array.
they have also probably undersized the cable, causing the inverter to raise the local grid voltage beyond the protection limits causing it to cut out - either that or you have very high grid impedance on your incoming supply / high grid voltage anyway, or maybe a lot of other solar installs on the same line.
I'll post up a graph of a system we've been monitoring that has hard shading coming across it from 5.30pm, without this function enabled it was doing as yours is, with it enabled it's reducing output by around 10-20% as the shading runs across the array.
OP
davey_b
- Reaction score
- 205
Just the whole thing. Is it in the loft directly below the panels or somewhere else? Where the isolators are, how they connect to the inverter, what cable has been used...
It's probably been done correctly and only the shading is impacting on output but if there's something wrong, you've got a few dozen experienced installers who might spot it.
OP
davey_b
OK, that all makes sense.
I spoke to a guy called Iain Garner from Tigo this afternoon about their optimisers. That was really helpful and it seems that the kit that they have could help us overcome this issue. Also solarmax have now said that we'll need a new inverter since there is the issue with a fan failure! Hopefully we'll get there in the end.
I spoke to a guy called Iain Garner from Tigo this afternoon about their optimisers. That was really helpful and it seems that the kit that they have could help us overcome this issue. Also solarmax have now said that we'll need a new inverter since there is the issue with a fan failure! Hopefully we'll get there in the end.
OP
davey_b
Ok, here's some photos. It's in the loft just below the panels.
Last edited by a moderator:
OP
oliver s
Looks to me that the pos and neg are the wrong way round in the inverter if the tape on the cables are correct? only looks like 1.5 flex to the AC isolator 2.5 at best, should be 6mm, 4mm at worst. Are there any other isolators for the DC supply from the array. In all doesn't look too good would definitely get them back
- Reaction score
- 205
Are there any DC isolators or are they somehow built into the inverter? Doesn't look like it to me.
There should really be a label on the inverter but that's small fry compared to other issues. The four cables flying thru the loftspace aren't best practice either. They should really be clipped or run in trunking and clearly labelled.
No fireproof board behind the inverter either...
There should really be a label on the inverter but that's small fry compared to other issues. The four cables flying thru the loftspace aren't best practice either. They should really be clipped or run in trunking and clearly labelled.
No fireproof board behind the inverter either...
OP
davey_b
There's an isolator between the meter and the consumer unit but that's it as far as I can see.
Do you mean the cable that runs from the inverter to the ac isolator in the loft is too thin? The grey twin and earth? What effect would that have? Could it cause the inverter to restart as shown in the videos I posted earlier?
Thanks guys, this is a big help and feel I'm getting to grips with it.
Do you mean the cable that runs from the inverter to the ac isolator in the loft is too thin? The grey twin and earth? What effect would that have? Could it cause the inverter to restart as shown in the videos I posted earlier?
Thanks guys, this is a big help and feel I'm getting to grips with it.
OP
oliver s
The main concern is the white cable from the bottom of the isolator which should go to your consumer unit via another isolator and the generation meter this would cause conciderable volt drop and loss in generation but the main issue is the positive and negative the wrong way round from the panels this would cause the problems you have, don't be tempted to swop them round as there are no isolators and would be very dangerous, it definitely needs looking at by someone who knows what they are doing
OP
oliver s
I would agree with that
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