ktmrfs
I measured my MPPT controller efficiency which is documented in the graphs above. Even did a few static measurements with external meters and obtained very similar results. The unit does better than what Morningstar claims - from my expereince they tend to be a bit conserative with their specifications / ratings.
Looking forward to seeing your data posted
Yes indeed its all about I/O POWER as in Wattage with MPPT controllers
For me the solar system is a power source for my power hungry loads not a battery charger - the battery bank is typically fully charged by 11:00am.