Tigo optimisers - 25% mismatch rule help

[solaruser2024]

Hi

We have 6 panels on one string with TSA-4 optimisers. 3 panels on the south-facing roof, 2 on the north-facing roof and 1 on the north-facing roof. (Connected to a libbi 5kw inverter.)

Currently, our inverter is saying that it's getting volts: 90.8V, current: 10.52A, Power: 957W.

However, Tigo is saying it's delivering a total power of 1295W, so things are not adding up.

Speaking to Tigo support, they've highlighted the 25% mismatch rule, and it would be great to get someone's opinion on whether my understanding is correct.

Based on the picture below, it's clear that A6 is doing nothing, but am I right in my understanding that due to the A5 and A4 having a greater than 25% mismatch, these will not be contributing to the final power sent to the investor, too?




If this is correct, is there any way around this with Tigo, or would SolarEdge optimisers (which I understand doesn't have the 25% rule) or Enphase be required to make all 6 panels work?

Thanks
Scott



Should it be of any use, here are the voltage and current screenshots.

 

[timselectric]

We have 6 panels on one string with TSA-4 optimisers. 3 panels on the south-facing roof, 2 on the north-facing roof and 1 on the north-facing roof.

This is the problem.
All panels in a single string need to face the same direction.
Optimizers can't fix this design flaw.
The entire string is limited to the lowest performing panel.
And because they are facing different directions, there will always be panels underperforming.
The only solution is to put each different facing array on its own SCC (Solar Charge Controller).

 

[mvreddy48]

Another solution could be to put diffent direction facing panels in parallel instead of series.

 

[BentleyJ]

Another solution could be to put diffent direction facing panels in parallel instead of series.

Yes, but in parallel, if the minimum MPPT start up voltage is not reached there will be 0 output.

 

[solaruser2024]

Yes, but in parallel, if the minimum MPPT start up voltage is not reached there will be 0 output.

This is why we’ve ended up with optimisers, but it appears to have not worked as expected.