Solaredge - Modbus info indicating grid is down?

It probably depends on the home automation system and what kind of input it might use. I would need more information about which home automation system you have, and whether it is just software based or hardware/software based?

A simple relay, wired to the grid, that opens or closes a contact would work, if the home automation system can use a contact closure as input. As far as reliability is concerned, an electromechanical process may be more reliable than Modbus or CAN messages.

Right now my main experience is with HomeSeer (HS3/4). I have been considering moving to HomeAssistant if necessary.

The issue is that I won't have a separate critical loads panel, only the main panel and whole house backup with either 32 or 48 kWh batteries (2 - 3 x LG RESU 16H). The SE system switches over to battery in 1.5 - 2 seconds so i guess we can monitor for a transient outage as the signal that the grid is out. But how to differentiate between transient <30 second grid outage and a real one....

A Homeseer script should be able to do that. If it is only a 30 second grid outage it would depend on the trigger you used but when the outage is over the condition would disappear. It has been a while since I used Homeseer but when I was using it, it could accommodate a number of different hardware devices, some of which were able to sense contact closure. As I mentioned earlier that would be the simplest since it is the basic process used for burglar alarm systems.

Thanks Ampster ! However, if the whole house panel is being backed up by switching to battery automatically, I don't know enough electrical engineering know where to install a sensor/relay that would sense that the outage is ongoing or truly over, as the house would now be running on battery backup from the LG RESU 16H...

The SE inverter connection in the LG Resu has AC grid input. Perhaps the inverter could signal when grid is down? Do you know anything about what signals the SE inverter sends. I think there is an API but my only SE is 400 miles away so I can't test it. Perhaps there is a SE user group? Presumably the SE would know if the outage is over?
If that does not work then you may have to change your strategy and base your load shedding on battery SOC.

There are several SolarEdge API calls that show inverter status and operational mode, shows battery state (charging/discharging/idle...), energy/power info, etc.

The only down sides are:

1) The inverter reports everything directly to SolarEdge, and you can use the API to communicate with SolarEdge to get information that has been collected. The "inverter technical data" API, which has the status of the inverter over a time period has a resolution of five minute intervals. Not an instance indication of power failure.

2) The API restricts to 300 calls per day. One call can collect status for a period of time (the inverter technical data can report on a week's worth of data).

3) There is a delay from when data is collected and when you can see it. For example. I may check at 10:30 AM, but see data up to 10:10 AM.

It would be great if one could directly query the inverter through an API (probably is a way, but either proprietary or SolarEdge restricts access). If anyone knows how, please let me know!


There is a free SolarEdge app, that will allow you to set the reserve charge level for the battery (if you have admin access for the site). I have mine set to 20%, so the battery will discharge down to 20% capacity. It also has a "weather guard" mode, where, if there is a large storm forcasted, it will not use the battery at all, so that it is at 100% in case of an outage.



On my setup, I have a battery, Energy Hub, and Back Up Interface, with generator, but the integration is not working yet (a very long and painful story), and fortunately we have not had a big outage this Winter (yet - fingers crossed), so I don't have much API data on grid-fail cases.


Attached is the latest API doc...
se_monitoring_api-08-2022.pdf