Hello,
I have an array of 8 x 230W identical PV panels. They are working fine for about five months now, direct charging (parallel connected) a 24V battery string.
I want to reconfigure the battery string for 48V mode so I first tried to reconfigure the PV panels.
Well, after putting two by two panels in series (then paralleling the four groups) and connect them to the same 24V battery string, I found out that in every particular series string, the measured voltage on every panel is different. For example, even the series string has a voltage of 24V, inside a string I've got 16V on one panel and 8V on the other. I've got similar results on all four series string.
I know that PV panels are working as current sources mainly but doesn't it look quite strange? Like I said before, all the panels are identical - I mean the same manufacturer, same model and bought them at the same time. All the panels are mounted side by side in open sky (no shadows).