mppt vs pwm

There is always power point tracking, it's only maximized in bulk when as said the batteries can take it. What controls the buck converters output after bulk is the same as in PWM, the voltage and acceptance rate of the battery. Should a load bring the battery below float, it will return to bulk/MPPT. Should a load keep it from achieving the absorb set point, it will stay in MPPT at what ever level you balance it at.

It's not like there is some hidden power that is only there in bulk/MPPT. The power is just tweaked to bring up the battery the fastest. That's why I can pull the same amps in float as I do in MPPT.