Power management apparatus and method of operating the same

A method of operating a power management apparatus, the power management apparatus electrically connected to a renewable energy generation apparatus and a load to form a first path and the power management apparatus electrically connected to an AC utility and the load to form a second path;

• steps of the method comprising:
• (a) providing a power conversion unit to convert an output power generated from the renewable energy generation apparatus to supply the AC utility and the load;
• (b) providing a first sensing unit and a second sensing unit to sense a first current and a first voltage of the first path and a second current and a second voltage of the second path, respectively;
• (c) providing a switch unit and a control unit;
• (d) electrically connecting the renewable energy generation apparatus in parallel to the AC utility when the control unit turns on the switch unit;
• the control unit acquires an output power generated from the renewable energy generation apparatus according to the first current and the first voltage and acquires a feedback power to the AC utility according to the second current and the second voltage;
• and a power difference between the output power and the feedback power is provided to supply the load;
• and
• (e) supplying power to the load by the renewable energy generation apparatus in a stand-alone operation when the control unit turns off the switch unit.