Cool. Doing something similar, so adding to this thread.
Trying to measure the output from a small solar panel with Automation Hat (not the phat, but they are similar).
I have the first analog input connected to the battery plus to measure battery output, and that seems to work fine. Trying to connect the second analog to the plus from the solar panel, but am not getting a correct reading. The multimeter shows one value but the Automation Hat test program shows the same value all the time - around 12 volts.
What I can’t understand from the docs is if I should connect solar panel minus to the ground on the hat or not. I have googled for examples of using this input, but can’t find any. Also can’t find docs on the difference between “buffered inputs” and “inputs”. (Newbie warning, but in learning mode).