How to detect power blackout with Shelly products

[FredFromAfrica]

Dear community, I live in Africa and we face a lot of black outs.

My setup:

I am using an off grid inverter witch supplies the house with current from pv modules during the day and at night with batteries. When the battery comes to 35% state of charge the inverter switches into bypass and supply the loads in the house from the grid.

I keep this 35% reserve to have back up power when it comes to a black out.

I would like to avoid that the aircondition drains the batteries when the grid is off otherwise my batteries are empty in 3-4 hours.

My question.

which Shelly product can I use to detect that the grid is off ? I thought about the Shelly Uni but I realized that it cannot measure 230v. Only up to 30 v if I remember well. My next idea was to connect a bulb to the grid and to use a Shelly EM to identify if the bulb is on or off. Once the Shelly em detects that no current flows to the bulb it would start a simple automation and switch off an other Shelly pro which is in front of the aircondition.

All Shelly products are supplied by the power of the inverter and it’s secured that they don’t lose  power or Wi-Fi connection during the power outage.

Do you have a better solution or Shelly product to realize this scenario?

best regards 

Fred

 

Edited July 25 by FredFromAfrica

[thgoebel]

There are special voltage relay available which detect under- or overvoltage:

Amazon

The linked part has adjustable limits which trigger an internal relay (NO/NC). With an additional Shelly plus 1 (e.g.) the dry signal contact (NO) has to be wired between terminal SW and L if the Shelly. The contact closure may be used to signalise power outages.

[FredFromAfrica]

Thanks a lot for this tip, I will try it !