Solar energy system with built-in battery charger and it's method

A solar power extension method to expand solar power usage, i.e. to maximize peak sun hour, said method comprising a minimum grid power import means with charge/discharge of storage batteries to make the most of solar power and minimize grid power usage.

A solar power conversion system (PCS) with built-in high power storage battery charger/discharger and a method to maximize solar power and minimize grid power usages using storage battery comprising a MFPCS to convert solar power to AC grid power, charge/discharge storage battery in high power, an operation mode 1 for operating MFPCS as interleaved multi-phase battery charger, an operation mode 2 for operating MFPCS as solar power converter plus direct battery charger, an operation mode 3 for operating MFPCS as solar power converter, an operation mode 4 for operating MFPCS as solar power converter plus battery discharger, and an operation mode 5 for operating MFPCS as AC PWM rectifier battery charger;

• comprising a method with the steps of:
• calculating a output power PS of a solar power source, a load power PL and a State of Charge (SOC) of a battery power source, determining on peak-hour/off peak-hour periods in accordance with time of the day, sensing a output voltage VMP of a solar power source, a terminal voltage VB of a battery power source, performing logic comparison operations of SOC, PS and PL, VMP and VB, selecting operation mode, setting battery charging power reference and inverter power reference based on logic comparison operations, performing control functions according to the selected operation mode and power references.