Compatability issues with SMA HF and Sanyo panels

[confounded]

No we have exactly same problem with fronius inverter.Tested all panels on install and short circuit all the correct readings from the array up to the DC isolater. It goes down hill after that
SMA have no idea or solutions to this problem but I suspect its not an inverter problem now as we have now tried 2 SMA 2500HF and a fronius inverter . All do the same
Not exactly impressed with SMA myself.

Any joy in solving this issue?

We have had one system that is performing in the way described on this thread and having changed from an SMA to a Fronius the issue is greatly improved however still present on the odd occasion. The customer is being very patient but is keen to get it sorted in time for next year.

We are finding that the system is not loosing many kWh's of production due to this issue but they do find it very frustrating that on the brightest and highest producing days the system is under-performing.

 

[confounded]

Any joy in solving this issue?

We have had one system that is performing in the way described on this thread and having changed from an SMA to a Fronius the issue is greatly improved however still present on the odd occasion. The customer is being very patient but is keen to get it sorted in time for next year.

We are finding that the system is not loosing many kWh's of production due to this issue but they do find it very frustrating that on the brightest and highest producing days the system is under-performing.

Anyone got any updates?

 

[solman]

Hi

I've just read all 9 pages of the SMA - Samyo panel issue and would like an update if anyone has any news. I have a 10 panel Sanyo HIT 250 system using an SMA2500HF inverter mounted outside on a north facing wall. The customer is reporting the same drp off of power which is rest to expected levels by switching the system off/on. Have reported the issue to SMA but heard nithing yet.

Solman

 

[danesol]

I know everyone is a bit busy at the moment but has anyone had any joy resolving this issue?

pm sent

 

[Energetic]

Hi

I've just read all 9 pages of the SMA - Samyo panel issue and would like an update if anyone has any news. I have a 10 panel Sanyo HIT 250 system using an SMA2500HF inverter mounted outside on a north facing wall. The customer is reporting the same drp off of power which is rest to expected levels by switching the system off/on. Have reported the issue to SMA but heard nithing yet.

Solman

'north facing wall' Seriously?

 

[Energetic]

I do have something to add to this now, We have/had been working with Sanyo sending data from Sunny Explorer and screenshots from PV-Sol at the time the problems are occuring.

We do have some shading which i am willing to concede may be a contributing factor. Sanyo are saying that the shading is confusing the MPPT on the HF inverters causing them to bottom out and stay bottomed out.

SMA have said this may be a possibility and advised using Opti Trac, they gave us this advice in early Jan. The problem is we went to SMA with this issue in July and the HF series did not have Opti trac then or we would have tried it, as others on this thread have suggested. It is available now on HFs and can be retrofitted with a firmware upgrade.

All of this is very well and good but IF this is a shading issue, why does resetting the inverter, or even the DC isolators resolve it with NO change to the shade pattern? Sanyo have been very quick to deny all responsibility and sent out an email refuting claims made by installers on this and other forums, claiming there's no issues with their panels. They have been completely unable to answer the fundamental questions and just blame poor system design. I am not yet convinced.

One factor worth bearing in mind is the layout of the strings within each panel, the N series has parallel (geometrically) strings down the length of the panel while the H series has a band in the middle with two larger areas at each end of the panel. Each seperate string has its own blocking diode so the system can take shading if it is on up to 2 of the strings, if it covers all three expect a major reduction in output.

SMA have not helped much, other than to replace inverters with new inverters that do the same thing. Every time i phone for an update i have to explain from the beginning to someone new who asks all the same questions and who never gets back to me. As our customers were getting hacked off with us being unable to get answers we replaced the inverter with a fronius IG TL. The firmware upgrade with optitrac for the HF series came too late for us but i'd be interested to know if it works for anyone else?

The Fronius is behaving far better than the SMA did. My gut feeling on this after all the hassle is that there is some sort of incompatibility between the inverter(MPPT) and panel which is possibly exacerbated by shading.

I hope this helps and hasn't come across as too much of a rant, i appreciate that Sanyo and SMA have assisted us but i am still very frustrated that we have no resolution.

 

[FB.]

The solar panels have no moving parts, little in the way of fancy electronics and no intelligence; they just faithfully convert light to electricity. It seems hard to imagine how they could be the cause of the problem unless there's something wrong with their bypass circuits.

On the other hand; "artificial intelligence" - such as a inverter's (M)PPT - is only going to be as good as the program and processor which runs it. How many times have you played a computer which is generally hard to beat but occasionally it "artificial intellligence" makes a howler of a mistake?

I would put my money on it being an inverter processor/factory-programming hiccup. Perhaps it is occurring because quite a lot of inverters - even different makes - are using the same programming algorithm to run the (M)PPT? Perhaps the MPPT has not been properly tested in a part-shaded situation, since only an over-generous Feed-in-Tariff would encourage such inefficient deployment of solar PV as to put it in shady placed.

 

[Gavin A]

All of this is very well and good but IF this is a shading issue, why does resetting the inverter, or even the DC isolators resolve it with NO change to the shade pattern?

Resetting the inverter would have the same effect as using optitrac global peak because the inverter searches the full voltage range on start up, just as it does when using global peak (it's why the inverter output jumps around so much in the first few seconds after it starts up).

I can see this sort of problem happening on a system where shading started impacting on several strings of cells at once, eg a hard shadow from a chimney, TV aerial, soil stack etc sweeping up the array from the short side of one or more panels. This could easily place move the MPP outside of the range of the sweep of the standard MPPT system, and the output would reduce gradually from that point as the shading increased, because the MPPT would be still stuck at the old peak point and wouldn't move to the true peak point to allow the bypass diodes to function properly... something along those lines anyway.

Have you got any pictures of the array at the point where this problem was happening?

 

[morpheus75]

in response to a PM just thought i will provide a bit of update on this:
Since changing inverter to the powerone 3.6 outd i have had better output when compared with my friends. Recently had good sunshine and have had it peak at 2.8kw and no cutoff in production. I have never had to reset for any reason. So in my case changing inverter has worked for me. I managed to sell the sma that i took off and installed at a clients place with a chinese panel (cant remember off hand the name) and that is on south facing and performing fantastically aswell so inverter wasnt faulty just goes to prove that their was some sort of incompatibility. Hope this helps

 

[Energetic]

Righto, my last word on this (i sincerely hope). I'll post it in both threads so subscribers to both will see it.

After some great advice from member of this forum and some further digging with Sanyo, SMA and Fronuis we have been able to close this issue off.

As has been suggested by members here the large instantaneous drop in voltage caused by the operation of the by-pass diode on the Sanyo H-Series panel drops the array voltage outside the MPP trackers scanning range causing it to get stuck on a false peak. Its is particularly problematic with the H-series due to the large number of cells in the two end sections. See image:

View attachment By-pass configurantion H, N.pdf

I have been told that SMA's opti-trac was developed as a direct result of this known issue with their tracker. It is worth noting that this information did not come from SMA, they denied all along that the problem was anything to do with their product, they did not advise us to try optitrac when it became available and as far as i know did not release any info publicly in response to a problem that was being reported several time a day at its peak.

Fronuis were unable to offer an update similar to optitrac as they have not had the problem frequently enough to warrant it. We have now installed the third 3000HF, this time with opti-trac and the problem has been resolved.

I must be clear that this is not a fault with the panels or inverters as such, they work as they are designed to. The problem is one of compatibility, a specific panel, inverter and shade combination is the cause and removing any one of the three will resolve the issue. Opti-trac rescans at set intervals and therefor doesn't allow the tracking of a false peak.

I'm glad to have this resolved finally and would like to thank everyone of the forum who offered advice and also SMA, Fronuis and Sanyo for taking it seriously and coming up with some answers.

Finally i would advise anyone with H series panels and hard shading to monitor their system closely, part shading doesn't automatically mean poor performance and we have seen the system perform at near peak with the shading when the tracker is working correctly.

If you are considering PV and you have a shading issue get a quote from an installer who uses PV-Sol or equivalent who can model the system and quantify the imact the shading will have. I do wonder how many other systems are out there with this issue that has yet to be noticed.

Over and out...

 

[Gavin A]

good to hear. Do I get a gold trouble shooting badge?

interestingly, we appear to have a very similar problem that's been reported by a customer with sanyo N series panels on an older SB2500 inverter that as far as we can work out didn't have any shading at all.

I shall be investigating once they return from holiday.

 

[SolarCity]

good to hear. Do I get a gold trouble shooting badge?

I reckon you should get two!

Well done Gavin. It was a nightmare of a problem and we'll all have an idea what to do if it happens in the future.

 

[danesol]

I have this combination and dont have an issue at all, although my shading is different as its not partial but fully both before 9am and 4'sh

 

[Energetic]

I reckon you should get two!

Well done Gavin. It was a nightmare of a problem and we'll all have an idea what to do if it happens in the future.

Indeed, thank you Gav, strangely enough both Sanyo and Fronius came up with essentially the same prognosis as you in the same week! I couldn't possibly say that they saw your posts but we know they watch this forum... ;-)