Automatically turn off power to home appliances power supply switches to backup generator
You could look into home automation techniques. Appliances can be controlled with WiFi, Bluetooth, powerline communication, or even a wired control connection with low-voltage control wiring routed on wall surfaces. There is a lot of general information available on the internet. Look at this Wikipedia article and follow links to other articles you will find in the article. There is also a lot of home automation product information available on the internet. If you want to design something yourself, search for do-it-yourself (DIY) articles about home automation.