I don't understand worrying about electrical efficiency if that didn't get you more amps per dollar as the true measure of efficiency
My batteries (and so the same for me) only care about amps. MPPT is just a hard way to get more amps. "Efficiency" should be measured in amps per dollar. If MPPT got you more amps per dollar, that would be the way to go.
At some bigger array size there is a cross-over price point when MPPT gets more amps per dollar, but that would be a bigger (in watts and panel area) array than most Rvers would have based on some recent posts on that topic where costs were worked out.
I only care about amps. (12v-PWM guy) When I buy a panel I look at its Isc. Don't care about its watts, except as a marker for what Isc to expect.
In operation, I check the Isc on the panel aimed in full sun and then look at the amps going to the battery. Should be the same. If not, I fix what's wrong and now I'm good.
