Been grappling the past several days with a tricky situation for my software to handle. On a cloudy day, the charge controller gets the batteries to around 85% and then it starts reducing the watts produced. It seems to be in an absorb stage, although this CC only reports boost/float and claims it's in boost. Sometimes it will be in this state for hours.
Turning on the fridge at this point is desirable, because rather than producing 64 watts through clouds, it'll suddenly be producing 200 watts.
But, it could also be that the battery got to 85% full and then it got very dark out, and it's only able to eke out 64 watts max, and then turning on the fridge will start draining the battery at the worst time.
One way to solve this would be to install a light meter. Trying to find a good one that can be put safely in a good location is not easy. The best ones are i2c bus and so difficult to get far from the computer.
Could try to diy a 1-wire using https://www.edom-plc.pl/index.php/en/1-wire-i-rpi-en/159-lightintensity
Or I could try to briefly switch on a load other than the fridge, to probe if more watts can be produced. Eg a light or heating element (perhaps the one in my old propane fridge).
I'm currently trying to solve it in software, by looking at all the data, especially the voltage, I hope to be able to detect the absorb state.
"Luckily" I have had plenty of opportunity to grapple with this due to a total lack of direct sunlight this week. The fridge is keeping between the lines, but only because I'm noticing this situation and manually overriding it to turn on.