I've had some old Arco 16-2000 solar panels stashed for a couple decades and now I'm finally going to put them on a tracker and cut 'em loose. According to an old Home Power magazine, issue #3, Feb. '88, they don't need regulation from a controller. Since each panel has 33 cells, and each cell puts out .46 volts, the maximum power of 15.2 volts won't ever overcharge a 12 volt battery. It sounds like they were specifically manufactured to follow the charge curve of a 12 volt battery. Has anyone ever used panels with 32 or 33 cells, without a controller/regulator? Joe