Fly-back switching power supply circuit suitable for photovoltaic system

The utility model discloses a fly-back switching power supply circuit suitable for a photovoltaic system, comprising a power-on power supply circuit, a PWM control circuit with voltage-current feedback, a MOSFET gate drive protection circuit, a fly-back converter, an RC absorption circuit and an auxiliary power supply circuit. The fly-back switching power supply circuit of the utility model has a reliable structure. The power-on power supply circuit accesses a voltage detection unit, allowing a power supply to act only when the input voltage energy is high enough to maintain normal operation of the system, so that the problem is solved of frequency start/stop (hiccup) of a switching power supply during low light conditions in the morning and evening, the power supply and the system are protected from being damaged, and the reliability of the power supply is enhanced.