Our entire home is run like a UPS. Power is always on as long as we have battery power. The batteries are recharged via solar panels and the grid. I need a device that can be connected to the grid and will send a signal to eisy when power is on or off. This would allow, eisy to switch our home to a more conservative power level should the grid be out (such as turning off non-essential devices). I could use a relay tied to an Insteon door sensor. But that would mean that the relay would be on all the time the grid is on - which is most of the time: the relay would most likely burn out over time. And this seems like a waste of power. Looking for a more eloquent solution. Maybe a Hall Effect Sensor in the transfer switch box. Has anyone done something like this? Or does anyone have any thoughts on a better solution? Thank you

I have a ZOOZ Range Extender https://www.thesmartesthouse.com/collections/zooz/products/zooz-800-series-z-wave-plus-range-extender-zac38 that reports power loss. It connects via z-wave and has a battery backup.

Maybe something like that connected to the grid side of your power?

A relay coil draws mere milliamps and will not overheat or deteriorate because it's on for long periods. I wouldn't worry about that.

Use a 120VAC solid state relay, not an electromagnetic one. The only downside is the output contacts don’t behave like the dry contacts on a electromagnetic relay in that they don’t pull down to 0 ohms.

I had somewhat of a similar idea except it involved a 26kw whole home generator that feeds the home's electrical panel. I wanted to reduce non-essential loads during a power outage when running on generator. Essentially load shedding.

My solution was a Shelly EM-1 (WiFi) with 2 x 120A probes on the generator's supply lines into the transfer switch. Tells me exactly how much load in watts, kW, or Amps the house is drawing on the generator. Based on that I can define very granular load shedding in Home Assistant and resume certain loads when that load drops below a threshold for a sustained period.

It worked out really well, but that got me into thinking - hey, it would be really helpful to know exactly what load draws are for most of the individual circuits in our home in real time. So I also installed an Emporia Vue Energy monitor in my main panel. 2 x 200A probes on the mains and 16 50A probes to monitor 16 of the most active circuits in my home. Connected that into the Energy Monitoring in Home Assistant and it gave all kinds of graphs, charts, and data in real time.