Posted a solution yesterday on my blog http://handyharley.blogspot.com
My method involves using a Raspberry Pi connected to my UPS to flip a virtual switch in Smartthings via Webhooks and IFTTT. It’s a flexible solution with tons of capability for add-on features. My RPi3 is running at 0.1% CPU, and I’m using only three Webhooks triggers and one Smartthings virtual switch.