This is my 300w GoPower sitting behind my electric panel.
Two transfer relays in the black box to the left. I can't see the 12v connection but ir should be on the right of the inverter and it connects behind. Red battery cable is the very bottom right but the connection is out of view. Pic is looking in with the electric panel removed.
I chose GoPower for lowest idle draw and provision to add a remote switch.
See three position power switch on front and green connector just below.
Sorry no wireless :(
If installing to day I would use the small
KISAE TS15A 15A Automatic Transfer Switch $50I have two switches because I wanted power on both convenience outlet circuits. These are connected after the branch circuit breaker.