The invention discloses an inverter without a transformer realized by a switched capacitor. The inverter comprises two capacitors, five power switches and a filter; two ends of the first capacitor are connected to a drain of the first power switch and a second input end of the filter respectively; a source of the first capacitor is connected to a drain of the second power switch, a first end of the second capacitor and a drain of the fourth power switch respectively; a source of the second power switch is connected to a second end of the first capacitor and a drain of the third power switch, a source of the third power switch is connected to the second end of the second capacitor and a source of the fifth power switch; and the drain of the fifth power switch is connected to a source of the fourth power switch and the first input end of the filter. The invention further discloses applications of the inverter in a photovoltaic grid electricity generating system. The inverter disclosed by the invention is simple in structure and capable of effectively inhibiting earth leakage current in the photovoltaic grid electricity generating system.