The GoPower! TS-30 Automatic Transfer Switch is typically installed to allow both your inverter and shore power / generator to alternatively feed the circuits and it prevents AC back feed (thus protecting your inverter). The TS-30 is a 30A AC switch that will automatically connect shore / generator power (when available) to your breaker panel.
When it is unplugged from shore power (or the generator is turned off), it then will connect your inverter output to power your circuits. It can handle (2) 30A inputs at the same time and is equipped with knockouts for easy installation.