It is very easy to use the Prop as a direct solar panel MPPT controller for a brushed or BLDC motor (for instance a pump). In this case you can use a PWM motor driver or 3phase ESC. There is a lot of voltage and current ripple, so the measurements need filtering and averaging.
In the case of solar panels connected to sensitive sensors and staged battery chargers a much smoother and accurate controller is needed, such as an adjustable switched mode power supply.
I have found that the cheap adjustable switched mode power supply modules on ebay and other online stores are quite efficient and smooth.
The voltage adjustment seems to be universally controlled by a 10K pot.
It is quite simple to remove the 10K pot and solder in a pin header for control by the Prop via a Digital Pot.
In the case of solar panels, a high voltage digital pot is required, for instance MCP41HV51.
Attached is photograph of some modified switched mode power supply modules.