Sun renewables solar panel problem( with pictures )

[Cs111]

I know some of you guys have panels from sun renewables who I also understand are no longer trading. Though companies house have them as still active. 

I’m after some advice really.

 

fronius inverter, sharp panels

 

I noticed that there is only approx half of the normal kw of electricity being produced by the panels over the past week - would days. 

We have a 4kw system split into 2 strings, today we were only seeing about 1300w. - 1800w 

On inspection of the fronius primo inverter there is a code

STATE 522 DC1 Input Voltage too low

 

It seems to be showing 0w - 10w being produced on dc1 and normal production or approx 1600w - 1800w on dc2.

 

 

any ideas would be appreciated

 

 

 

 

 

Edited July 3, 2018 by Cs111
Added pictures

[Jeremy Harris]

Looks like one string of panels has gone open circuit.  Most likely culprit will be a connector in that string I think.  The only easy way to tell is to get up on the roof and have a look at the connectors.

 

There can be problems if connectors aren't crimped to the cables correctly, leading to overheating and an open circuit, but equally it could be something as simple as a connector that's somehow been subjected to strain and just come unplugged - I've heard of that happening when people have poked around trying to clear birds nests from underneath panels.

 

As a test, you can turn off the DC isolators and then swap over the DC inputs on the inverter (they should just plug in).  If you then turn the DC isolators back on and the fault shifts to MPPT 2 you know that it's the panel string that is at fault, not the inverter.  FWIW, my money is on a duff connection on the string feeding MPPT 1.

[PeterW]

Could always isolate both strings, switch the connections between input 1 and input 2 to see if the fault "moves" which would indicate either a cable issue or a connection issue to the strings. Reading the MPPT figures though it would indicate the panels have output.

 

Have you got the manual..?

 

Crossed with JSH

[ProDave]

I would have said inverter fault as both strings seem to show the same voltage.

 

I would also swap the strings over, and to be really safe wait until after dark to do that just in case you touch the wrong thing, And see if tomorrow the fault shows on the same string, in which case it is an inverter problem, or the fault moves to the other side in which case it is a panel or wiring fault.

[Jeremy Harris]

I've got a feeling that the indicated MPPT voltage floats up when a string goes open circuit, from internal leakage, but you might be right.  Swapping the strings over on the inverter should prove it one way or the other though.

[Cs111]

Here are a couple more pics Showing mppt1 and mppt2  

 

So you mean swapping over the 4 black cables ( 2 with red tops ) 

i don’t think they will simply unplug but will have a closer look later tonight and made sure I switch everything off just incase 

[Jeremy Harris]

It doesn't look as if the DC connections unplug, but there should be a pair of DC isolator switches fitted, one for each string, so that the system can be made safe.  These are usually fitted right next to the inverter, but don't seem to be in your case.  The usual type fitted are quarter turn rotary switches, with a yellow or white case and red knob.  These isolate the DC from the panel strings so allowing the inverter to be replaced, and I thought they were a mandatory requirement.

 

The four wires going in to the bottom are the cables from the two strings a positive and negative for each, and MPPT1 and MPPT2 should be marked inside next to the terminals, or on the underside of the cover, perhaps.  Because you have to access the terminals by removing that cover, the instructions on it need to be followed, to turn off both the DC and AC isolator switches.  Often the inverter AC isolator switch will be fitted right next to the generation meter and consumer unit connection.

[Cs111]

[Cs111]

There is a quarter turn knob under the inverter if you look just to the left of the red wires

[PeterW]

19 minutes ago, Cs111 said:

There is a quarter turn knob under the inverter if you look just to the left of the red wires

 

That shouldn’t be the only isolator. Is there a pair in an attic somewhere ..?

[Cs111]

Il have a quick look later and update but not that I know off. 

There are a couple of guys on here that have an install by the same company, perhaps they can also comment on the isolator or lack off 

Edited July 3, 2018 by Cs111

[Onoff]

You could repost on the Talk Electrician forum and search out @binky on there. He's a solar guru.

 

https://talk.electricianforum.co.uk

[Cs111]

Ok so I had a look in attic and followed the 4 black wires from the roof right down to the inverter and no other isolator or switches of any type. 

Had a look at the quarter turn knob on the bottom of the invertor, it says disconnect beside it if that helps 

Edited July 3, 2018 by Cs111

[Declan52]

Same guys done mine looks wired up like that.

 

[Cs111]

Just swapped over the 2 sets of wires and it’s now showing the same message except state 523. Instead of state 522. 

 

i will check the mppt tomorrow when there is some daylight 

 

why would  U PV1 be showing approx twice the V of U PV2 ? 

 

Also so here is a screenshot from fronius regarding the 2 codes , 522 and 523. Note 523 is slightly different from 522

 

 

Edited July 3, 2018 by Cs111

[Declan52]

The fault codes are below so by swapping the wires the fault has moved to the other string. Is that not what was supposed to happen.

 

[SteamyTea]

I seem to remember that you need to turn the invert off before you turn the DC side off, though should not matter if you are playing at night.

 

It is not unusual to loose a string and in ever case I looked at it was always a connector that had loosened.  Sometimes these are really hard to snap together, and even harder to unsnap.

Pain in the arse if it is one under a module, they are usually hard to get to even with scaffolding.

If it s a major job, then MCS are meant to step in and fix it if the company has stopped trading.  But good luck with claiming via them.

[Jeremy Harris]

That test has confirmed that it's the string at fault, not the inverter.  @SteamyTea is dead right, this isn't unusual and they can be a pain to get at, as the connectors are under the panels on the roof.

[Cs111]

Yea just checked invertor screen and the fault has swapped to mppt2 now showing 0w.

so that confirms it’s a panel,  connection fault. 

Next step I guess it to check each panel one by one. Is it safe to do this with the invertor , ac switch off ? 

[ProDave]

You also want the DC isolators turned off before touching the panels. That ensures no current path on the panel side.

[SteamyTea]

You are playing with unearthed DC, so you become part of the earth circuit.

Now this should not be a problem as each junction should be designed to be save to handle.

But if one is broken and a wire exposed, even in fairly low light you can get a nasty shock, and you will be on a roof.

So take great care in what you are doing.

[Cs111]

Ummm ok. Don’t want to be taking any unnecessary risks to be honest. 

If I isolate the dc connections ( 2 black wires and the other 2 black wires with red tops going into the invertor from the solar panels ) also switch off the AC isolator will there still be a danger from the panels themselves when disconnecting them one by one and checking over the connectors? 

[Jeremy Harris]

Yes, the panel wires are always live in daylight, and as they are wired in series in each string you can get quite high voltages at the ends of the strings.  However, the inter-panel  connectors are designed to be hard to accidentally touch the live part, and a fault may well be physically obvious.  The most common faults are pulled apart connectors, where something has physically dislodged them, and burned out connectors, usually where the internal crimp to the cable wasn't made properly.  The latter usually shows as heat damage to the outside of the plastic part of the connector.

 

Less common faults can be an interconnect ribbon within a panel failing, which usually means replacing the panel.  Take a meter up with you, capable of reading several hundred volts DC, and check the panel voltages at the connectors as you go.  That way you should be able to trace where the fault is in the string.

 

Because your working on live DC, albeit isolated from earth, a pair of insulated gloves would be a good idea.

[SteamyTea]

The connectors are sometimes really hard to get apart, this is why they can become broken.  Too many people pull them bu the cables rather than release them properly.

Also  to repair one you would  need a proper crimper and crimps to do a proper job.

And remember that each panel can produce about 70V and 3 or 4 amps, so 5 modules in series could be 350V.

Get a good wallop of that.

[Cs111]

Just thought I’d update the thread. After some investigation and phone calls I got in touch with guys who set up and also work(ed) for sun renewables. 

Came out yesterday and also today and found a connector on one of the panels had overheated. 

All sorted now. 

Glad I didn’t try myself as I would have never found it. One of the guys spent 4 hours yesterday on the roof testing and removing panels and couldn’t find the problem