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dave-brannigan asked

Odd Charge behaviour

I have two Panel arrays, one single panel using a 75/15 MPPT controller and 2 parallel panels to a 100/30 controller. Both connected to the same battery bank Panles next to eachother with no shading. Neither one seems to be outputting as much as I felt it ought to be given that I purposely took the battery below 85% SOC to test them.

At one point with the battery near 90%SOC the smaller controller turned itself right down to 0.2 A whilst the larger one continued to give more than 7A. All panels in clear full sun.

They have potential to give up to 340 Watts but getting at best around 160W on a clear blue sky day in June. Why would one controller shut down with such demand on it? Both running V1.64 firmware.

MPPT SmartSolar
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Alexandra avatar image Alexandra ♦ commented ·
The voltages on the battery side maybe?


Also hot panels produce under their rating (datasheet raring is 25°C which no panel ever is in the sun)

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dave-brannigan answered ·

Thanks for comment. Battery voltages would be the same for both controllers. Same battery bank. Yes if the battery was near capacity and charging was ramping down but at 85% there is still a way to go. Accept that heat de-rates the panel but these panels have produced a lot better previously. I recently updated the firmware in both controllers to 1.64. Not sure how to go back and see if that makes a difference to the max output, but it doesn't explain why one would essentially go off whilst the other is in bulk state does it?

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