Compatability issues with SMA HF and Sanyo panels

[Energetic]

I have an issue with a system which i can't get my head around. If anyone can shed some light on it it would be much appreciated...

The rig is 12x sanyo 250w on a SB3000HF inverter on a nearly west facing roof.

The problem is as follows:

At between 1430 and 1500 on a bright sunny cloudless day it will drop from over 2kw output to <500w (it's gone as low as 200w) in small 5w increments over about 5 min. The problem lasts about 10min then creeps back up to the normal level in similar small increments. The inverter logs no faults or events of any kind. During this period the string current drops to less than 1A. The issue is not occuring on anything other than a bright sunny cloudless day.

I spent several hours on the phone to SMA who replaced the original inverter as they themselves were stumped. Their report came back with no faults. The replacement inverter has not solved the problem.

If the isolators are turned off and the inverter is reset during this time period the power comes straight back up to the expected output, ie >2kw and does not creep up incrementally as it does if left alone.

Surely if there was a poor connection somewhere it would not happen at such a regular time? Below is an image of the drop in action, the drop prior to 1200 is a cloud the other is not. If anyone has any ideas i'd be grateful...




Cheers...

 

[BruceB]

Re: Help with fault?

I hestitate to suggest anything if you have already had a long conversation with SMA, but....
- is the inverter overheating, then winding back the power until it cools down, then ramping it up again?
- is it inverter getting a blip on the power curve, with the tracker following it down, then following it up again?
- a blip on the curve could be caused by shading from the usual suspects, trees, poles, power line, telephone line or a cat or a bird sitting on the array.
- is the array accessible so you can check the connections?
- try a good long short circuit test in bright sunlight to stress the array and connections and check the current stays high.

Let us know when you solve it!
Regards
Bruce

 

[SolarCity]

Re: Help with fault?

It seems to be at the peak when the inverter goes through this process, and this is consistent with the fact that it only happens on bright sunny days.

Where is the inverter located? Does it have plenty of space to 'breathe'? I would expect that an overheating inverter would produce an error message but this doesn't appear to be the case.

I would suggest that BruceB's suggestion of a poor connection may be the likely culprit. I would visit site and carry out some tests before, during and after the drop in power takes place.

 

[Energetic]

Re: Help with fault?

Cheers guys,

The first thing that SMA came back with was overheating but said it would be logging it as an event if this were the case, the next thing was grid overvoltage, which again should be logged.

The fact that it is so regular indicated to me that it may be an array problem but if this is the case why does it clear if the inverter is re-started? If its a duff panel why isn't it happening all the time?

It seems like bright sunny days are going to be few and far between for the next few weeks at least so might struggle to get tests done during the event. Its probably our worst job for access also, 3 stories and tiles that break as soon as you go near them. Scaffold will be required for any array access. I can retest the string but it came out normal on commissioning, what else should i look for?

Cheers...

 

[LOTH001]

Re: Help with fault?

Cheers guys,

The first thing that SMA came back with was overheating but said it would be logging it as an event if this were the case, the next thing was grid overvoltage, which again should be logged.

The fact that it is so regular indicated to me that it may be an array problem but if this is the case why does it clear if the inverter is re-started? If its a duff panel why isn't it happening all the time?

It seems like bright sunny days are going to be few and far between for the next few weeks at least so might struggle to get tests done during the event. Its probably our worst job for access also, 3 stories and tiles that break as soon as you go near them. Scaffold will be required for any array access. I can retest the string but it came out normal on commissioning, what else should i look for?

Cheers...

I have the same set up as you 12 x sanyo 250 and sma 300hf inverter works great, you have looked at the obviouse do you have 1 string? panel failure so uncommom and sanyo especially hard one as you need to be there when happening if you were could trip all mcbs other than pv in case something happening in house but unlikly is the install in urban area or remote? faulty inverter unlikely as you have had 2 will put thinking cap on and get back if anything springs to mind

regards

 

[Cider]

Re: Help with fault?

Could be a crack in a panel circuit expanding when hot and at the same time high current?
Suppose you need to sit in the loft with a meter on the string for a few hours.

 

[Energetic]

Re: Help with fault?

Hi Guys, i still have the same problem on a sunny day. We've done a test today and rather than resetting the inverter just the string isolator was turned off and back on, the output immediately went back up to over 2000w. Any ideas would be great, all i can think of is getting the scaffolding back and retesting each individual panel. I am now at least satisfied that the inverter cannot be at fault.

 

[PvNewbie]

Re: Help with fault?

What were Vsc/Isc before/after switching isolator off/on. I can't see how anything on the roof can be affected by switching the isolator!!??

 

[dansk]

Re: Help with fault?

As daft as it sounds it may be the isolator, ive had weird crap in the past such as Fuse spur causing RCD to trip with load going through it - maybe on a hot day too much current is going through and the isolator has a weak connection - god knows, but if its was a panel/heat related/crack in a cell/what ever then switching the array off then back on wouldnt clear the fault.

But by turning of the iso would shut the inverter down, so i would continue to look down that route. Testing each panel again would give reasurrance.

 

[Energetic]

Re: Help with fault?

Went out there today, it had dropped away twice in full sun today to under 500w it was reset both times with the DC isolator and went back to high output. I was advised by a tech support fella at one of our wholesalers to change out the cheap components first, isolator, sunclix etc as they are more likely to fail than Sanyo panels so have done that.

Also as advised in a previous post here to short the array out to stress it out, did that for a good 15 min in full sun whilst fiddling Isc sat at 6.8A the whole time.

Looks like another decent day tomorrow so should know pretty soon if it has worked. next step is scaffolding and taking array to peices...

 

[dansk]

Re: Help with fault?

I guess scaffold back up is cheaper, but, could you try another brand of inverter? Do you, someone on here, loan you an inverter? I know you have swapped it like for like, but its still the same brand.

 

[TMGL]

Re: Help with fault?

Bizarre timing but I got a call today...sounds like exactly the same problem. Customer saying at around 1.30 p.m. Output drops from 2.9 kw to 301w...cloudless sky. I was flummoxed! Sma sb 4000tl...fitting team and sparky have done over 200 installs so confident that strings are correct.

 

[Energetic]

Re: Help with fault?

It's an odd one... are they Sanyo panels by any chance?

 

[TMGL]

Re: Help with fault?

Yup, 17 235's n series from memory. Up in the Scottish Borders...best day for a while today. He did 12 units before 1 p.m. And then 1 unit between 1p.m. And dusk. I'd have preferred it if the system had gone off altogether as it would have been easier to identify the problem! I'm not an electrician but have a fair bit of pv experience and it's a new one on me.

 

[Energetic]

Re: Help with fault?

The plot thickens... Try the isolator on off business and see what happens. I was told today that most panel faults are characterised by stable voltage and a serious drop off in current... Not looking forward to testing individual panels for an intermittant fault, will need 12 clamp meters ;-) and lots of sun...

 

[TMGL]

Re: Help with fault?

It will be an integrated dc isolator on the 4000tl so might just reset inverter tomorrow to see if the experience is as yours. Supplied by segen or AS solar if that's also a common link?

 

[Energetic]

Re: Help with fault?

Yesterdays figure, clearly showing the point of dropoff, now not even coming back up untill reset on the DC isolator. Might have to try swapping the Inverter out for a fronius... Can't really think of anything that will definitively give me an answer. Nobody else other than TMGL heard of this happening/had this happen? PM me please if you can't admit it on the forum, i won't tell... If you know of anyone that might be able to help please a pass their details on.

 

[SolarCity]

Re: Help with fault?

Did you change the DC isolator in the end?

 

[Energetic]

Re: Help with fault?

Yes, new isolator, new tails and sunclix into the inverter. Same stuff happening, behaves completely normally after a 10 second switchoff... Wondering if it could be a firmware issue but there must be tens of thousands of Sanyo/SMA installs out there now...

 

[SolarCity]

Re: Help with fault?

Sounds very much like a loose connection somewhere to me - possibly on a panel itself. Judging by the data you have shown, the problem appears to be getting worse - I would say this is consistent with a loose connection that is getting very hot. However, the fact that switching on and off at the DC isolator lets the system reset contradicts this conclusion.

Have you checked the resistance of the circuit during peak times?

 

[MorganPVI]

Re: Help with fault?

Whats your earth like?

We've had a dodgy connection on the 4000tl on the earth connect the clip was on the earth sheath, it was fine in the cloud but once the sun came out the inverter powered down - would not work over 2kw o/p. Re seated the earth clip on bare metal and it hit 4kw no issues.

 

[Energetic]

Re: Help with fault?

@ Biggs, my tester doesn't like me trying to get a resistance when there's lots of DC voltage present, how is this done?

@ Morgan, it's PME at 0.11 if that's the earth you mean? The array frame is not earthed. Do you mean the clip terminal on the inverter?

 

[MorganPVI]

Re: Help with fault?

Yes on the 4000tl the AC is connected with spring clips, iiirc same as a 2500.

I'm wary of the 2500, we fitted one and it would not generate more than 2500w, given the high irradiance this really struck me as odd and makes me think there is some kind of software control on these units. Given you've swapped one inverter out already i'd suspect some kind of issue with the panels, is it possible to fit another make of inverter, personally I'd be trying that before getting the scaffers back. Seems a real tricky fault to deal with.

 

[SolarCity]

Re: Help with fault?

@ Biggs, my tester doesn't like me trying to get a resistance when there's lots of DC voltage present, how is this done?

To be honest, I've not tried it. I test insulation resistance to earth but I've not tried getting a reading between pos and neg - The tester probably won't like it.

 

[confounded]

Re: Help with fault?

We got a call yesterday from a customer with a 2000HF and 10 235W Sanyo panels with this exact issue. Beautiful cloudless day and he got home to find his system was flat lining at 200W having dropped from 1800W at the peak of the day. As energitic says when I told him to switch the isolators on and off the system then bounced straight back up to normal and stayed there all day.

Not a big installer but have a good number of systems behind us without any other faults. This is a strange one!

 

[TMGL]

Re: Help with fault?

So 3 identical problems...all sma/sanyo installs. Admittedly this will be a very common combination but still more than a coincidence surely? Wonder if it's possible to rename the thread 'sanyo/sma install problems' to see if we can attract more data?

 

[Eco Deal]

Re: Help with fault?

Have you guys not over looked the country setting issue , I did an sma 4000TL and didnt change the setting to g83??

a good sunny days the invert would drop , like describe I went back to check and changed thre country setting to uk g83

NO problems reported since .

 

[Energetic]

Re: Help with fault?

The momentum is building on this with SMA and Segen and Sanyo looking into it now.

 

[ExtremePV]

Re: Help with fault?

What is the AC grid voltage when this happens?
And have you enabled / check if Optitrac enabled?

 

[Energetic]

Re: Help with fault?

G83 is on, optitrac off, grid voltage is within parameters. would optitrac help? SMA havent asked about that. Still no event codes for anything.

 

[edexlab]

Re: Help with fault?

@ Biggs, my tester doesn't like me trying to get a resistance when there's lots of DC voltage present, how is this done?



I think the only way you could do this in the day would be to cover the array and test this would be pretty difficult to do, when we first started I did this on a small display array of 4 panels we had just to see how practical it would be , simple answer is it isn't but it may well rule out the panel fault theory

 

[ExtremePV]

Re: Help with fault?

Try enabling optitac. I've got a hunch it might help...

 

[The Launderer]

Re: Help with fault?

Our first install, on my own house is 12 x Sanyo HIT N240's in 1 string and SB 2500HF. The weather in Central Scotland has been pretty crap since the install last week and the generation figures are not impressive.

These are the figures:

Fri 30/9/11 - 4.9kWh
Sat 1/10/11 - 0.5 kWh
Sun 2/10/11 - 2.3kWh
Mon 3/10/11 - 2.9kwH

Can anyone tell me if these are typical figures or have I got a problem?

 

[confounded]

Re: Help with fault?

It is quite likely you have a problem, certainly when only generating 0.5kWh on Saturday, although the fault we have is only occurring on the clearest and brightest days.

I recommend you interrogate your data on Sunny explorer by connecting to your inverter using a bluetooth enabled lap top. The fault being discussed on this thread is very distinctive due the the drop off being so rapid (3000W down to 300W for example) and then holding at a low level until reset.

 

[edexlab]

On Sunny explorer can you access any events logged like on the sunnybeam ? ie grid disturbance I can't find this
I know you can look at the graphs to see when drops in output occur which will give you times etc, but when you have a scenario like this it would be useful

 

[The Launderer]

Re: Help with fault?

It is quite likely you have a problem, certainly when only generating 0.5kWh on Saturday, although the fault we have is only occurring on the clearest and brightest days.

I recommend you interrogate your data on Sunny explorer by connecting to your inverter using a bluetooth enabled lap top. The fault being discussed on this thread is very distinctive due the the drop of being so rapid (3000W down to 300W for example) and then holding at a low level until reset.

Got MCS accreditation visit tomorrow. If we pass I am really going to get into the nitty gritty of interrogating the inverter.

Saturday was a really horrible day - rained all day and very dark all day.

Sorry if I am on the wrong thread. New here and not to sure of the protocol. Should I have started a new thread?

 

[confounded]

Re: Help with fault?

Got MCS accreditation visit tomorrow. If we pass I am really going to get into the nitty gritty of interrogating the inverter.

Saturday was a really horrible day - rained all day and very dark all day.

Sorry if I am on the wrong thread. New here and not to sure of the protocol. Should I have started a new thread?

Ok, good luck with your MCS certification, a fault will be obvious when you do get a chance to interrogate with Sunny Explorer.

There is another thread that may interest you.
[h=2]Low system output during indian summer? [/h]

 

[Energetic]

Explorer has been really useful for hunting out our issue. The daily graphs i have posted in this thread clearly show the problem. The data can also be exported in .csv files for each day showing the output in 5 minute intervals which is quite useful.

Event logs can be accessed and also exported to excel files with more detail than what is available on sunny beam.

 

[The Launderer]

Re: Help with fault?

Ok, good luck with your MCS certification, a fault will be obvious when you do get a chance to interrogate with Sunny Explorer.

There is another thread that may interest you.
Low system output during indian summer?

Indian Summer in Scotland? You're having a laugh!!

More like Monsoon. Our Indian summer amounted to 1 nice afternoon.

 

[Energetic]

Advised today that the TL inverters as stated by morgan123 in a previous post can power down if there's no earth connection as they dump, which is why they shouldn't be on a 30mA RCD.

Inverter swapped today for another brand...

Thanks to SMA UK for their help and support. Just waiting on a sunny day to see if it worked... Will keep you informed...