It looks like they re using a fixed voltage point pwm system.
I use that system for solar water pumps, but in the water pumps case, it uses the inductive properties of the solar pump motor to make the current conversion.... the solar industry calls it current booster technology.....
It revolves around not letting the panel voltage drop below a pre ordained set point via pwm control....... You don't need a processor to do this....a comparator will do it anyway.
They are probably on the right track in some regards. True MPPT seems to be really useless if you use 60 cell panels on a 24v system ( 250w panels using 6x6 cells), your switching losses barely (in fact probably wont) actually give you any gain except for flat battery conditions.
My solar controller uses simple pwm and 60 cell panels, and testing against expensive name brand mppt controllers has not had any useful improvement.... (struggled to find any improvement at all under these conditions)
When you go to high volts ( ie 90v for a 24 or 48v system) then the difference is marked, but at low differentials, probably not worth the mppt. Their fixed point will probably do every bit as well on lv panels ( 60 cell not 72 cell ones).
Not sure why they would use the fixed point without driving an inductive device...... maybe batteries are exhibiting some inductance, and thats enough to make a difference.
But it is not mppt in the normal sense of the word... and in some circumstances can be better, in others worse.... test it and see, but use 60 cell panels if you can source them, your already a few amps per panel better for starters using 60 not 72cell panels ( 8A for the 60cells and 5A for the 72 cell ones ( roughly)).
My home brew 100a controller is noisy, and needs attention ( RFI) if theirs is as good as mine and quiet ( RFI) , it will be very useful.
.................oztules