As raised in my post about solar panels and batteries in the take on mars suggestions forum that i recommend reading here http://forums.bistudio.com/showthread.php?160558-batteries-and-solar-panels.
here are my two suggestions about power management of mainely rovers as probs don't consume that much energy.
-Making full power solar panel recharge chem batteries or alowing us to redirect the solar energy to the chem batteries foreseeing more night venturing.
-Allowing control of where the electricity come from or restrict the use of a source of energy.
those two together would make rover use only solar panel energy at day and chem batteries at night.