All details in my Kickstarter page description including user manual , HW, SW as is a fully open source project.
https://www.kickstarter.com/projects/electrodacus/solar-bms-and-digital-mppt-for-pv-electricty-and-h
I don't quite understand the mechanism. I assume the goal of MPPT is to harvest the maximum possible power from the panel and direct all of this power to the battery with minimum losses. If the MPPT point for the solar panel is, say, at 30V, and the battery is at 12V, how may it be possible to satisfy both of these voltages without a DC-to-DC converter?
If you look at the DMPPT450 user manual you will find the principal of operation and what that DMPPT450 is good for. The simplified diagram will help you better understand how it works but I will try to explain here in a few words.
The DMPPT450 uses as input a large PV array in my case 10kWp and there are 6 outputs where resistive heating elements are connected each with a different value and by connecting a number of this heating elements you load the PV array with one of the 32 or even 64 levels (6 outputs with different resistance say 1,2,4,8... ohm just an example get's you up to 64 levels thus the digital part).
So you get the max power point but since there are 32 to 64 power levels that can be selected by changing the 6 resistive load outputs to ON or OFF the max power point tracking is digital.
You can of course also just connect a fixed heat element to the array so max power point is when you get max amount of sun on the panels and that way in a sunny day you can get up to 80% efficiency with just the simple fixed element but in a cloudy day it can be as bad as just 20% or less so average over a year may be just 50 to 60% with fixed value resistive heat element but with DMPPT450 is always above 93% and as high as 99%
This is one of the parts of the DMPPT450 the other part is that it can divert one up to 6 of the PV inputs to the SBMS120 keeping the output to what you specified in the SBMS120 menu.
In my case I have a 24V 180Ah battery so about 5kWh and to protect the battery charge current should be keep under 50A but the 39x 260W panels over 10kWp is way more than that over 300 even 400A in ideal conditions so the DMPPT450 is able to only divert some of the 6 inputs each connected to a number of panels so that it gets as close as possible to the 50A limit set.
This way in a sunny day it may only redirect 6 panels to battery charging the rest of 33 panels are used for heating with digital max power point and in case of an overcast day it can redirect all panels as long they are outputting under 50A as LiFePO4 gets priority over thermal mass storage that way battery capacity can be about 3x or even more smaller than what will normally be needed for same energy usage as battery will be fully charged even in worst overcast day with the huge PV array.
My small offgrid house is a net zero energy house as all energy for electricity and heating is provided by the 10kW PV array and this is the most cost effective solution even compared to natural gas.