Fronius/Sanyo/SMA compatability problems?

[nothappy]

I have a 3KW system which I have been having problems with since installation. Originally I had an SMA inverter but the problems were still the same.

The system works well in general but there are occasions when the system power will decrease over a period of time (30-45mins) in bright and sunny conditions. When I spot this occuring I have to shut the system down for a couple of minutes. When the system boots up again the output is good. The difference can be from 250w before shutdown to 2KW afterwards.

There is sometimes shading on the panels and I accept that there will be a drop in output because of shading but the shading is still in the same place after the system has booted up again so how can that be a problem, especially after only a couple of minutes?

I have contacted the installers who have been very helpful but I gather that Fronius and Sharp are not being very helpful. Whatever theories that people come up with all sound very reasonable until you add the arguement 'but why does the system suddenly work well after I turn it off and on again'.

Any help would be gratefully recieved.

 

[Glen Powell]

Re: Fronius/Sharp/SMA compatability problems?

First off more info required

Array size
Panel sizes
Inverter
1 string / 2 string

Is there any error readings on the inverters

My first guess is heat build up due to bad connection creating losses with the possibility of incorrectly sized wire, this is a real stab in the dark.

 

[Eco Deal]

Re: Fronius/Sharp/SMA compatability problems?

Id say wrong country setting

 

[Glen Powell]

Re: Fronius/Sharp/SMA compatability problems?

Do fronius have a country setting?? I thought they were plug and play

 

[nothappy]

Re: Fronius/Sharp/SMA compatability problems?

12 X Sanyo 250w panels. Fronius IG TL. One string. No error codes.

This does not always happen on a hot day. The most recent occurance was a couple of days ago when, yes it was warm, but not hot. On that day it actually happened twice. Once around midday and once again around 2pm. Obvoiusly the shading had moved during that time.

It was hotter today and we had an output of 2.6kw but there was a lot of fast moving cloud. It tends not to happen when there is cloud moving, causing the output to vary naturally. The problem tends to be when there is a sustained output over a period if time. It does not tend to happen with a sustained output in low light conditions when it will happily give me 500w all day without a problem.

If it a bad connection, why does the problem stop when the system is turned off/on?

Many thanks for your help. Your input and suggestions are really appreciated.

 

[Glen Powell]

Re: Fronius/Sharp/SMA compatability problems?

It gets a chance to cool

 

[nothappy]

Re: Fronius/Sharp/SMA compatability problems?

What difference would having the wrong country setting make?

 

[Glen Powell]

Re: Fronius/Sharp/SMA compatability problems?

In my opinion none, but I have not set the country settings incorrectly to find out either, it would work or not work

 

[nothappy]

Re: Fronius/Sharp/SMA compatability problems?

Sorry but the panels are Sanyo - not Sharp!!!

 

[Glen Powell]

I dont think the panels make a difference in the problems you are having.

 

[nothappy]

I dont think the panels make a difference in the problems you are having.

Probably not but I thought I had better correct my mistake as it might make a difference to someone, maybe with a similar problem.

 

[Energetic]

Sounds a similar problem to one we've had, there's a long (9 page) thread about sanyo/sma compatibility on here somewhere.

We have ruled out shading as the system still has problems when the shading is minimal, ie< a third of a panel and not covering multiple bypass diode strings within the panel, or non existant.

We have been working with SMA and Sanyo and Fronius for months and nobody can offer us a resolution. We have changed all connectors, isolators etc and the problem remains. As with yours the system will hit peak during periods of interrupted sunshine between clouds but struggles with clear uninterrupted sun untill it is reset.

It seems this problem is quite big, SMA have told us that there were several being reported a day at its peak, i think more will begin to come out of the woodwork now the generating season has begun.

Our feeling is that it is something to do with the software on the inverter running the MPP tracker. We have recently had an admission that the trackers can sometimes have problems and get themselves into a bit of a pickle but are still awaiting some more detail. Everyone seems to be at ecobuild...

 

[Gavin A]

I have a 3KW system which I have been having problems with since installation. Originally I had an SMA inverter but the problems were still the same.

The system works well in general but there are occasions when the system power will decrease over a period of time (30-45mins) in bright and sunny conditions. When I spot this occuring I have to shut the system down for a couple of minutes. When the system boots up again the output is good. The difference can be from 250w before shutdown to 2KW afterwards.

There is sometimes shading on the panels and I accept that there will be a drop in output because of shading but the shading is still in the same place after the system has booted up again so how can that be a problem, especially after only a couple of minutes?

I have contacted the installers who have been very helpful but I gather that Fronius and Sharp are not being very helpful. Whatever theories that people come up with all sound very reasonable until you add the arguement 'but why does the system suddenly work well after I turn it off and on again'.

Any help would be gratefully recieved.

there's another thread on here about this issue.

I'm fairly sure I know what it is, but would need some photo's of the array taken at the time the problem occurs to confirm it.

Basically I believe this is a problem relating to shading of the panels, and the inverters MPPT's inability to cope with the rapid change in the peak point on the votage curve, which causes a more rapid drop in the MPP with sanyos than other panels when the bypass diodes ought to be kicking in, due to the individual voltage of each string in the panels being higher (or to be more precise, in the H series panels the 2 strings of cells on either end of the panel are significantly higher voltage than the middle string).

The problem is likely exacerbated because the Sanyo H series panels have the bypass diodes / strings running across the long side of the panel, not the short side as virtually all other panels do, so your installer may not have appreciated this when installing the system.

The reason this happens in peak sunlight is that that is when the shading is the hardest / difference between shaded and unshaded cells is highest.

the reason it sorts itself out when the inverter is switched off and on is that at this point the inverter MPPT system traverses the entire voltage range to check where the actual MPP is on the voltage curve, instead of getting stuck on a false peak. This is also the reason that the optitrac global peak function on the SMA inverters has been shown to sort this issue out, as it makes the inverter regularly track up and down the full voltage curve to check for other higher peak points every few minutes, instead of just searching around the local voltage peak it's sat at.

Sorry, I don't know if fronius have anything similar to the optitrac global peak function.

 

[Gavin A]

We have ruled out shading as the system still has problems when the shading is minimal, ie< a third of a panel and not covering multiple bypass diode strings within the panel, or non existant.

hmm. Have you actually been getting this problem when there's zero shading? That could change things.

Our feeling is that it is something to do with the software on the inverter running the MPP tracker. We have recently had an admission that the trackers can sometimes have problems and get themselves into a bit of a pickle but are still awaiting some more detail. Everyone seems to be at ecobuild...

Did you try the optitrac global peak function and it didn't work?


sorry, not trying to teach granny to suck eggs and that, just trying to get my head round it as we've installed a lot of sanyo systems with SMA inverters, and haven't had this issue hit us, so I'm trying to work out why not, plus work out what the issue could be in case we do get it hitting us. We tend to switch on the optitrac function as standard if there's shading on the system, so I was thinking this might well explain why we've not had the problem.

 

[Earthstore]

Good answer Gavin, and well worded if I may say.
This was for the first post....