Device and method for detecting photovoltaic module-to-ground insulativity and photovoltaic grid-connected power generation system

The invention discloses a device and method for detecting photovoltaic module-to-ground insulativity and a photovoltaic grid-connected power generation system. The detection device comprises a first detection resistor, a second detection resistor, a third detection resistor, a first switch device and a second switch device, wherein the first detection resistor is connected with an anode-to-ground resistor of a photovoltaic module in parallel; the second detection resistor is connected with a cathode-to-ground resistor of the photovoltaic module in parallel; the third detection resistor is connected with the first switch device in series; a series branch where the third detection resistor and the first switch device are located is connected with the second detection resistor in parallel, or the series branch is connected with the first detection resistor in parallel; the second switch device is used for controlling the conducting state between the common node of the first detection resistor and the second detection resistor and the ground wire of a photovoltaic inverter and is used for controlling the conducting state between the common node and the null line of a power supplying power grid. By the adoption of the technical scheme, reliability of detection on the photovoltaic module-to-ground insulativity is guaranteed.