over-paneling an MPPT controller.

[rickst29]

I have an MPPT controller which is rated for 30A (tracer 'BN-3215') and I typically run it into LFP batteries at 13.5 volts (and higher). That's 405 watts.

"Controller will be damaged when the PV array straight
polarity and the actual operation power of the PV array is three times
greater than the rated charge power!"

That specification indicates a hard limit of about 1200 watts. I'm about to upgrade my front shell panel array to 6 * 100 watts. Other solar controller might not have as much headroom as mine, check your own specifications carefully.

I don't want to put the controller under stress, and at most times of year the flat-mounted panels will not perform that well (even at solar noon). I think this upgrade from "400 watts" will be effective, safely providing full power for a longer period of time on "optimal" days near June 21, and 50% more power when the 6 * 100 watt panels are NOT providing more than about 425 watts of input power.

[Wavery]

If you wire your panels 2s3p, you will be fine (as you well know).

You will also need to get the $25 MT50 remote meter.

I have 2 of the BN4215 on 1500W of solar and they work fine. Although, I had trouble getting one to work when using it close to max rating. That's why I had to go with 2.

[rickst29]

Thanks for your comment! My wiring will be 3S-2P, with about 64 volts V-disconnected (PWM mode). With my "solar power into MPPT using the bargman" trick, I have already run the BN-3215 at maximum output current for extended periods.

Your 1500w was a lot closer to the "3x" max rating for s single controller, which could theoretically put out only about 545 watts as 13.6 volts with 40A current. (higher power or lower voltage than I have could have reach your 40A limit, causing MPPT "issues under" great sunlight into only one controller). My 800 watts into a single smaller one is only slightly worse than than your "two controller" configuration.