Switchover device advise please

[JaG]

I have fitted a 2000w Renogy Inverter and run one cable direct to the side of the microwave. The switch behind is not easily accessible so I am going to put in a crossover switch (I think, unless otherwise advised).
The switch I am looking for is where the microwave wires go in the bottom, live wire from inverter and live wire from ring main. I want the switch to be live on one side from the ring main then when on inverter, switched over to live on the other side. Hope I have explained it right.
Can someone point me to a link of where to buy what I need. I have tried the electrical shops and nobody has anything like that. Thanks in advance.

 

[Alanf75]

It's a while since I connected this up but I can confirm that the simple external on off switch just cuts power to the switch on the multiplus so it's either activated or not. It now means I can leave the inverter switch on to Inv/charge or just charge and activate it by the remote switch so I don't have to go digging into the cupboard when I want it on. For reference I used a standard Berker rocker switch similar to the others in the van.