South and West all fitted with Tigo - max current

Hello, I have a SOFAR inverter with two string inputs operating in 'independent' mode. There are 10x 400W panels on the East string which produce approx. 10A at 30V each on a sunny morning. The second string is made of four south-facing panels and two west facing panels. All 6 of these panels are fitted with TS4-A-0 optimizers.

This second mixed south & west string produces a max of slightly over 7A at 30V per panel (i.e. it never reaches the 10A of the East panel). Does this make sense when the sun is south facing and therefore shining directly onto the south panels? I'm guessing it does and that even though the south panels on their own could in theory produce approx. 10A, that the overall string power of 180v x 0.7A = 1.26W is better than the 4 south on their own producing 120v x 10A each = 1.2KW. The optimizers are therefore deciding that 0.7A is a sweeter operating spot?

The behaviour that I cannot understand however, is that the inverter display shows that the combined South and East panel string's overall power is oscillating quite rapidly - e.g. changing 2 or 3 times per second from about 1KW to a peak of about 1.4KW. While there is some sun haze variation, the sun intensity is not varying that rapidly. The 10 panels on the East string produce a relatively stable power output on the same days that the combined South & West panels are varying rapidly. Can this be explained by the Tiga Optimizers? My inverter was replaced (not for this reason) and this behaviour remained consistent so that rules out the inverter. I therefore suspect it is either a faulty panel, loose connection or faulty optimizer .... or are these types of rapid variations normal for strings fitted with optimizers even on relatively clear blue sky days during periods while none of the panels are in shade?

Any explanations would be greatly appreciated or should I be telling my installer that there is a fault somewhere in this string? BTW, the system is not fitted with a TAP or CCA.

- Peter.

Curtis

24. August 2022 16:53
Bearbeitet

Hello Peter,

Thank you for contributing to the Tigo Community.

Our engineers may be able to assist you with this issue but they would need some important design details. For this reason, I have opened up a service ticket for you, with our Support Team. They will be in touch, shortly.

In the meantime, please review this article for more information on issues with split orientations:
Designing your TS4 system for different tilts, angles, and orientation

Thank you for your patience with this process.

Olivia Barrow

28. September 2022 07:47

Dear Community members,

to follow up on Peter's issue, being it a non monitored system (blind deployment) we were only able to assume the reason why the mixed south & west facing string aren't delivering as much as expected, is the PV-Modules will never have every module facing the sun in the same way due to their position towards the solar window. When the sun is directly facing the 4 south modules, the other 2 west ones are producing less power than the other 4. Optimizers help mitigate this problem, but effectiveness wanes after 25% mismatch. The difference in production between the south and west facing modules most likely exceeds 25%, which is why Peter isn't seeing full production.

Your Tigo agents will always advise you to size your system (if possible) to have in each orientation enough panels to deliver the minimum input voltage of the inverter (V-Start). In the west orientation Peter could add some more panels to reach at least 120V and more!

We hope this was useful and we'd love to see this system on Tigo EI!

South and West all fitted with Tigo - max current

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