Charge Controller

Charge controller in general means an electric or electronic device that controls the charging of a battery. The most common function of such device is to stay between the charging power source and the battery and regulate the rate of current with which the battery is being changed (electric energy added to it).
In the context of renewable energy and solar photovoltaic (PV) systems the term has a slightly more specific meaning of a device that in an off grid (- this is part of the specifics here) photovoltaic system that on the electric diagram stays between the solar array(s) and the battery. It has the same function as defined as general above but why is this specific to the off grid PV systems? – Because in the more widely spread PV systems – the grid tied ones – the function of a battery charger is performed by a PV inverter and a separate charge controller is missing from the schematic. In fact inverter in the context of a PV system also has a specific meaning as opposed to the general term inverter. Inverter in general means a device that converts DC power in to AC one. PV inverters in addition to this DC to AC conversion function also serve a few other purposes as – charger controller (if a battery is involved at all), balancer between PV generated and grid power, some times also a controller for additional generating sources, like wind turbine, gas generator etc. Basically what is now called a PV inverter performs all of these many “brokering” functions of turning on and off and brokering the power between all possible generating sources, the grid and the load circuit (all the consumption of electricity in the system)