Since the VoltaBox system relies on solar energy to charge the battery, it has the usual limitations of any solar product-darkness, mostly cloudy days, or heavy shade. Hence, the VoltaBox comes standard with a 10-ampere Go Power! Smart Charger. This unit can be used to charge the VoltaBox battery should the situation warrant. It simply plugs into the 12-volt external power point to charge the battery from a wall outlet. This feature allows you to draw power from the VoltaBox in a shaded, remote area during the day, and then charge the unit at night in preparation for the next day's work.