Grid status

I have a Tesla powerwall and it is fantastic except for one little thing. There is no indication when the grid goes offline and it switches to battery power. That is not a big deal except living here in California and with temperatures in the 100s this time of the year the A/C will suck the battery down in no time. I would like to have some indication the grid is down so I can shut down the A/C and the battery will supply power till the next day when solar takes over.

How would I go about doing that? Are there any sensors/devices that would tell me that and indicate so in Smartthings (and Sharptools) at a reasonable cost? I know there are some at 100-200 dollars or move systems but I just want to see the grid status, nort what the whole house is doing.

You want this: [RELEASE] Tesla Powerwall Manager Smart App and Device Handler

You’ll get new integration features/possibilities - the main one being that you can have ST do anything you want upon grid failure and restore.