A lot of Solar power guys do this. I find if you unplug the power cord from your internet router/modem first, the miners lose their internet connection and are disconnected from the pool. Wait a few minutes for the miner fans to cool them off, then switch off the miners and reconnect the modem/router power.

It's a bad idea to just switch them off while they have been mining and are heated up. Heat will kill your chips so let them disconnect from the router/modem and cool with the fans for a few minutes beforehand.
Chris B.