The system uses battery power in priority sequence, but if sunlight is inadequate and the system fails to produce the demanded power or load consumption is too great then the system can switch automatically to grid power supply.When the batteries are restored to adequate capacity, the system can switch back to battery power source.
Off Grid Inverters
Inverters are used in PV systems to produce ac power from a dc source, such as a PV array or batteries. Inverter sizes range from module-level inverters rated a few hundred watts to utility-scale inverters 1 MW and larger. Similar to the way PV systems are classified, types of PV inverters are also defined based on their application in stand-alone, utility-interactive, or a combination of both types of systems.