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Does my tigo optimizer work correctly?

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Runolfsson35

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I have string inverter and single string of panels plus installed tigo optimizer into panel which gets occasional shade from chimney however the results are weird.

To my understanding tigo optimizers work by raising panel current (in order to match with rest of string current) and lower panel voltage. What happens in my installation when the shade on particular panel comes in is the opposite: the current drops and the voltage raises! Obviously that results in poor power output for the whole string as the current for the whole is the lowest one from all panels.

Does my tigo work correctly then or maybe it doesn't work at all? I read about investigation by Aussie installer who found entire batches of tigo come with pre-installed faulty firmware which makes them no-op (unless you connect them with their monitoring system and upgrade firmware). Could mine be affected as well considering above symptoms? Or is it normal behavior and I'm only misuderstanding how it works?
 
Last edited:
Runolfsson35 said:
I have string inverter and single string of panels plus installed tigo optimizer into panel which gets occasional shade from chimney however the results are weird.

To my understanding tigo optimizers work by raising panel current (in order to match with rest of string current) and lower panel voltage. What happens in my installation when the shade on particular panel comes in is the opposite: the current drops and the voltage raises! Obviously that results in poor power output for the whole string as the current for the whole is the lowest one from all panels.

Does my tigo work correctly then or maybe it doesn't work at all? I read about investigation by Aussie installer who found entire batches of tigo come with pre-installed faulty firmware which makes them no-op (unless you connect them with their monitoring system and upgrade firmware). Could mine be affected as well considering above symptoms? Or is it normal behavior and I'm only misuderstanding how it works?
Click to expand...
Smells like you indeed have a software issue to me. I just posted my experiences to Craig on the other thread.
 
An update after sunshine and time allowed for further Tigo testing yesterday:

The 6 panels with Tigos installed have been checked with a EY800W Solar Panel Multimeter and all performed well.
The Solax inverter has demonstrated to be able to run on 4 panels after bypassing 2 panels.

Conclusion: If the Solax inverter can run on 4 panels but does not run properly on 6 panels with Tigos installed, while 2 panels are partially shaded, that does mean that the Tigos do not live up to their promise of impedance matching and removing the effect shade on 2 panels has on the whole string.

My conclusion: The $442.42 I spend on Tigos have been wasted. I wish I had read Mark Cavanagh's blog before deciding on giving Tigo a go. (https://www.mcelectrical.com.au/tigo-optimiser-recall/)
 
Strousy said:
An update after sunshine and time allowed for further Tigo testing yesterday:

The 6 panels with Tigos installed have been checked with a EY800W Solar Panel Multimeter and all performed well.
The Solax inverter has demonstrated to be able to run on 4 panels after bypassing 2 panels.

Conclusion: If the Solax inverter can run on 4 panels but does not run properly on 6 panels with Tigos installed, while 2 panels are partially shaded, that does mean that the Tigos do not live up to their promise of impedance matching and removing the effect shade on 2 panels has on the whole string.

My conclusion: The $442.42 I spend on Tigos have been wasted. I wish I had read Mark Cavanagh's blog before deciding on giving Tigo a go. (https://www.mcelectrical.com.au/tigo-optimiser-recall/)
Click to expand...
When you are trying to bypass two partially shaded panels in a longer string, Tigo optimizers are doing nothing more than capitalizing on the bypass diodes that are already there (do little added-value in that situation).

Strings of mismatched panel specs and/or parallel strings of differing lengths are the situation where Tigo optimizers add the most value…
 
fafrd said:
When you are trying to bypass two partially shaded panels in a longer string, Tigo optimizers are doing nothing more than capitalizing on the bypass diodes that are already there (do little added-value in that situation).

Strings of mismatched panel specs and/or parallel strings of differing lengths are the situation where Tigo optimizers add the most value…
Click to expand...
Tigo optimisers cannot capitalize on the bypass diodes since the voltage accross a bypass diode (0.7V) is far too low to drive electronic circuitry of a Tigo. Tigos are not capable of utilizing bypass diodes while they are being powered by the panel. Only an independent power supply for the Tigos could solve this issue but this is not the way they have been designed. You are looking at design limitations here.

Life is a compromise and having an independed power supply for each Tigo unit would come with different draw backs. Not sure what would be best but I assume Tigo engineers did consider all this before they followed the route they did. Perhaps though, they did not.
 
fafrd said:
When you are trying to bypass two partially shaded panels in a longer string, Tigo optimizers are doing nothing more than capitalizing on the bypass diodes that are already there (do little added-value in that situation).

Strings of mismatched panel specs and/or parallel strings of differing lengths are the situation where Tigo optimizers add the most value…
Click to expand...
Re: Strings of mismatched panel specs and/or parallel strings of differing lengths are the situation where Tigo optimizers add the most value…

Cannot follow your thoughts here. Tigos are supposed to optimise the string they are part of, they have no function accross different strings. Tigos are supposed to mach the conductance of a panel (impedance if you wish) with what is optimum for the string inverter. Theoretically, they convert panel V into panel current to match the current of the other panels in the same string. I haven't seen it happen yet though.
 
Strousy said:
Re: Strings of mismatched panel specs and/or parallel strings of differing lengths are the situation where Tigo optimizers add the most value…

Cannot follow your thoughts here. Tigos are supposed to optimise the string they are part of, they have no function accross different strings. Tigos are supposed to mach the conductance of a panel (impedance if you wish) with what is optimum for the string inverter. Theoretically, they convert panel V into panel current to match the current of the other panels in the same string. I haven't seen it happen yet though.
Click to expand...
 
They are talking about parallel panels in a string on their page. The unevenness comes from using panels with different power capacities or putting panels in parallel doubling the theoretical current (en power) production capacity. Yes Tigos can compensate for unevenness within one string up to about 25% as they claim. However, since the Tigos can only work provided they receive power from the panel(s), they can never utilise the facility created by the by-pass diode. This is an advantage of string inverters like Fronius, they can force by-pass diodes into by-pass mode. Every design comes with its own limitations.

Tigo: "Tigo's optimizers (MLPE: TS4-A-O) can help to compensate for production losses due to uneven strings and PV-Module Mismatch, as long as the variance (between the parallel strings' output) remains below 25%." Their word choice of "uneven strings" is a bit unfortunate since they are talking about unevenness within one string and not between strings.
 
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