Optimising shaded strings, (with Tigo optimisers?)

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lucode asked Oct 16, '22

Optimising shaded strings, (with Tigo optimisers?)

I added 3 more solar panels to my installation equipped with a SmartSolar 150/100 inverter. Those 3 panels are directed to the morning sun at an angle of 90° to the rest of the totally 15 panels. (See the scheme).

As there is this kind of mismatch I consider installing 4 Tigo optimisers to the panels that are labelled "shaded"- The 3 new ones are as well partially shaded especially in autumn. Now I'm not sure it those Tigos would make sense. Seen from my logs the solar yield is not too bad, bad is far from optimal. Note the angle of the 12 panels is rather bad for a low cycling sun in winter.
Here is the log without the 3 new panels a few days ago (yield about 16kWh).

And here is the log with the 3 new panels a few days ago (yield about 18kWh).

As you can see the 3 panels facing East are improving the yield in the morning, but hampering a bit the yield in the evening.
As for the optimising, I assume that SmartSolar has only one MPPT which collects the power from 3 input strings. so if the Tigos don't work I would need to install an additional SmartSolar.
There are two existing posts in the forum, but those are not quite actual and also a bit contrarian in their conclusion. https://community.victronenergy.com/questions/898/tigo-optimisers-ts4-o-compatibility-with-victron-m.html
https://community.victronenergy.com/questions/21086/smartsolar-mppt-problem-with-tigo-optimizers.html
I will certainly publish my results here if I would install the Tigos, but eventually someone ha some more recent experience to share with running Tigos.

MPPT SmartSolar

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nickdb answered · Oct 17, 2022 at 02:42 PM

From the mppt manual:

9.5.8. Optimisers cannot be used

Do not use solar panels with optimisers together with the solar charger.

Nearly all optimisers contain an MPPT or other tracking mechanisms and this interferes with the MPPT algorithm in the solar charger.

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lucode answered · Oct 21, 2022 at 07:26 AM

Ok, after some more research I came to the conclusion that it isn't worth the money to invest in Tigos. Or at least not with using their expensive monitoring software as well. My decision is mostly based on this article, which claims that Tigo has major Firmware problems and that without the monitoring system you can't upgrade the devices to a working Firmware.
Besides this, the article gives some deep inside how MPPT optimisers (should) work in different scenarios.
https://www.mcelectrical.com.au/tigo-optimiser-recall/

Another interesting info (Video) about optimisers: https://www.youtube.com/watch?v=E9NVLB_OYSU&t=3s

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Answer 1 · 2022-10-16T15:26:09Z

wkirby answered · Oct 16, 2022 at 03:26 PM

Don't use optimisers with a MPPT charge controller. The two devices try to track the power point and the end up trying to compete with one another often ending with no production at times.
People have tried this before and ended up with very poor results.

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lucode commented · Oct 17, 2022 at 02:32 PM

I'm not taking about optimisers in general, but about Tigos TS4 and alike. Tigo optimisers are different they are designed to run in MPPT controller systems. https://support.tigoenergy.com/hc/en-us/articles/115015509168-Can-I-use-TS4-in-an-off-grid-system-i-e-with-a-charge-controller-
In their compatiblity list you can find nearly all the mayor brands, with the exemption of Victron, (For instane Fronius devices eg. https://www.tigoenergy.com/inverter-compatibility?search=fronius).
Many experts that where rather sceptical about optimisers have changed their mind and promote Tigos now as a viable solution for shaded panels. Mainly because it works and you need only to install optimisers for the shaded panels. There are even panel brands which offer solar panels with integrated Tigo alike optimisers instead of diodes now.

But make your own research please.

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Alexandra ♦ lucode commented · Oct 18, 2022 at 06:29 PM

@lucode

I think you need to check your link there. Victron is not listed.

The AC PV inverters like Fronius are however.

So direct from Victron in their documents it is a straight no on their MPPTs as @nickdb mentioned and @WKirby said.

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Alexandra ♦ Alexandra ♦ commented · Oct 18, 2022 at 06:32 PM

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Answer 2 · 2022-10-16T15:40:22Z

semlohnhoj answered · Oct 16, 2022 at 03:40 PM

Hi @lucode, the second chart has an extra hour at 19:00 which is making it look worse but taking readings from both charts at 16:00, 15:00, 16:00 and 17:00 show almost identical results. Even the half hour values look equivalent. I'm assuming the dropout at around 15:45 was weather related? The morning definitely looks better as you say though.

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lucode commented · Oct 17, 2022 at 02:38 PM

THX now are both in the same range.

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Answer 3 · 2022-10-18T18:51:44Z

bathnm answered · Oct 18, 2022 at 06:51 PM

@lucode Maybe talk to @safiery in Australia. They have optimisers that they have working with Victron Smart MPPTs.

I have a pair of Tigo TR-4's on my yacht. The two panels are connected in series to raise the voltage. They have been installed for about 6 months. I am nots are that they have improved the yield when one panel is shaded and the other isn't. Unfortunately I lost last years data in VRM so cant compare. I will say that last year I had situations where my two panels on occasions ran at MAX output, this year I have not seen them hit that, but the weather this year and last may have been different.

I am not yet convinced they have added value, but will be monitoring further. It is unfortunate that the Tigo monitoring system is so expensive as that would show what the units are doing.

I know that people say do not, but I am aware people are. I am also ware that they are not true MPPT trackers but more intelligent blocking diodes.

Good luck and please do report back.

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