Stacking batteries would give you twice the voltage and half the current flow across the electronics in any circuit. More current produces more heat, and therefor more wear and tear. This is the reason power companies use high voltage lines for long distance electricity transfer. It cuts the current way down, which lowers heat and makes a much more efficient system. (less loss due to heat loss) Would cutting the current down across the circuit help prolong the life of the PV? Just thinking out loud and looking for other views.
Grimm
Grimm