It should be noted that beyond PWM vs. MPPT I also tested MPPT to MPPT. I tested the Midnite KID MPPT, the Rogue MPT-3048 and the Genasun GV-10 to see if I could record any differences in performance between the three controllers. I could not.
Contrary to popular misconception not all MPPT controllers are truly a "high performance" MPPT product. To explain this as simply as I can, older MPPT technology would pause charging to check array voltage and find the maximum power point to track to. This was often referred to as "sweep & sleep"... After the pause it would then resume charging again. This pause and observe or sweep & sleep type of behavior can eat into charging performance especially on a boat that moves and the maximum power point or maximum voltage point is ever changing.
Many of the Chinese controllers sold on eBay, and various other places, use this older technology or, in some cases, are flat out lying that they are MPPT at all. I have seen a few of them labeled as "MPPT" that are in-fact PWM. It is a true buyer beware market when dealing with Chinese solar controllers via eBay and other venues.
Higher quality & high performance MPPT controllers, such as the three tested here, use more sophisticated charge algorithms. These algorithms continually test the maximum power point and can adjust output performance in fractions of a second. Midnite, Rogue, Genasun, Morningstar TriStar MPPT's, Outback and some others are all true high performance MPPT controllers well suited for marine applications.. eBay controllers, sold direct from Shenzhen, who the "F" knows what you are getting?? Heck you might as well go to Vegas, if you like throwing your money away. (wink)
Bottom line is the performance differences were within my equipments range of discernible resolution. Put simply, I noted no performance gains between the Midnite KID, Rogue MPT-3048 & the Genasun GV-10.
That said the differences between these MPPT controllers is in the options, programing ability and voltage and current carrying capability. The Genasun is inexpensive and any real programming changes require it to go back to the factory for a $50.00 charge. It is limited to 10A of output max. If the voltages fit your bank then it represents a great value in an MPPT controller and is very, very simple, provided your panel is not bigger than 150W..
The Midnite KID and Rogue MPT-3048 can be adjusted 18 ways from Sunday and both offer on-battery temp sensing. These are both 30A capable controllers.
The Rogue can handle battery banks of 12V, 24V, 36V and 48V and up to 100V of solar array. The MPT-3048 has an excellent computer interface and remote option as well. It is a rather large, heavy & robustly built controller which means out of the way mounting. This is where the remote display panel comes in very handy. The MPT-3048 comes standard with the remote battery temp sensor and is a tremendous value in a 30A full featured MPPT controller.
The Midnite KID can handle battery banks of 12V, 24V, 36V and 48V and up to 150V of solar array. It does not however offer a remote panel or computer interface. The marine version of the KID comes standard with the remote battery temp sensor.
If you have batteries that require specific charging parameters you would be wise to invest in a controller that has more options. The Midnite KID or the Rogue MPT-3048 fit this bill as would a Morningstar TriStar 30 MPPT.
Summary of MPPT vs. MPPT Performance:
MPPT Boost Performance Differences = Not Discernible / Three Way Tie
Programing Options = Midnite KID and Rogue MPT-3048 / Hands Down Winners
Best Value In A High Performance MPPT Controller = Genasun GV-10