This question already has an answer here:
Well I thought it would be either 12 or 18 but... I have a battery and a solar panel so I thought I'd just try it.
I actually measured the voltage to be 9.7 before hand (btw it's an old lead acid car battery) and then I measured the volts on the solar panel and it was 20 +- a few (bc clouds and what not) then I hooked up the positive to positive and negative to negative, and measured 10.2 volts. Why not 9.7 or 20!?
I'm theorizing that this is because the battery put a drain on the solar causing that things volts to drop, so not 20. And the solar is boosting the battery causing it's volts to increase so not 9.7... and of course the internal resistance of the battery is causing the whole thing to slide towards the lower end of the scale. Well is anything I said even making sense? Are there other considerations? Or is my original expectation right and it should read 20v and the solar setup is anomalous? lol.
Ps I took a few physics classes and even a circuits class years ago so if your answer gets technical I may still be able to follow.
Thanks in advance.
Edit: I drew this picture which is a simplified circuit diagram of my setup (voltages shown are only approximations):
If you get rid of the battery between points a and b you read 20, if you get rid of the solar panel you read 9, my question is simply why 10 and not 9 or 20? What calculation results in a 10? Is it an average, subtraction? In other words it doesn't look like it is simply related to either of the starting voltages. :/