the goal of mppt is to get the optimal power extraction of a solar panel. To accomplish this, the voltage and current must vary based on solar input and load. This prevents you from strongly controlling the dc link on the output of the dc/dc converter that is doing this. However, if you add a second stage, that second stage can create a more stable/constant output voltage as long as power draw allows it to be physically possible.
Please use this page as a starting point: https://www.mathworks.com/solutions/electrification/mppt-algorithm.html
