Hello! Im just starting out on smart home things and i have a question. I don’t have anything set up yet but is it possible to switch a light on and off with relay and mechanical switch. Lets say that i turn on the light by openhab and than turn off by mechanical switch and so on or the other way (switch on, openhab off). If so whats the best hardware to use… i have been looking at ESP8266 or something similar. Thanks!
Raspberry PI, openHABian and a ZigBee Stick called CC2531
Afterwards…if you want to use a Zwave device you also can buy a Zwave Stick.
But I reccoment starting with ZigBee and the ZigBee Addon of openHAB
Devices like Sonoff are cheap enough it might not be worth DIYing.
2 Likes
Using a Shelly device you might be able the build that one into (or better behind) an existing wall switch. The price is in the range of a Sonoff.
2 Likes
My 2 cents:
Both @rossko57 and @opus gave good advice, 
I have and use both in my home. The advantage to the Shelly is the size as it fits nicely behind an existing wall switch (I’m in US but you may want to pop the cover and see how much room you have) and allows control via OH or a physical switch.
@markymark mentioned the CC2531 USB stick that I also use and like. For this I use zigbee2mqtt and not the zigbee binding. You can try both and see what you prefer as OH allows options. 
Info for zigbee2mqtt:
You only need the “Getting Started” section to work with OH. I prefer zigbee2mqtt b/c it allows you to add any device that’s not already supported. 
1 Like