I've run into the situation where my 8kW Sunsynk inverter won't supply power unless the grid is available after it has shut down and been started up again. It has an earth bonding relay and CT coil fitted to prevent feeding back into the grid. The DC light is on but the AC is off (grid is down) and the normal light remains off.

Everything works perfectly when the grid fails however I've run into the situation where extended power outages have occasionally lead to the batteries running flat and the inverter shutting down entirely. It then becomes impossible to get the inverter to supply power. The inverter boots up fine and PV charges the batteries but the "normal" light does not come back on until the grid connection is restored by the municipality. It's like the inverter is waiting for a clean grid signal before it decides to start up. How can I force it to start it up in islanding mode without removing the CT coil or earth bonding relay? I cannot find (or figure out) what settings I need to change to make this happen.

When the grid comes back up, I'll hear a "click" (presumably from the earth bonding relay) and the inverter normal light comes on and the inverter starts supplying power.

We sometimes have extended power outages lasting days so waiting for the grid to come back while the batteries are full is extremely annoying.

Edited January 29Jan 29 by Surge
Better description of the problem

@Surge

The 8kW SS does not have a Earth Bonding relay built in. (unless some newer models have changed). The "Click" is merely a relay energising to re-connect (after serving a specific timeout) the grid to the inverter.

Did your installer install a Earth Bonding Relay / Permanent Bond, as mandated by your local supply rules?

There shouldn't be any specific settings to change, as supplying output to load should be a normal thing for SS/Deye inverters.

The installer installed an Earth Bonding relay in the solar AC DB (where the mains/inverter transfer switch, inverter supply switch and inverter load switches are located).

The inverter just sits charging the batteries until they're full but it never supplies any power until the grid comes back up. Once it's running I can switch the grid on and off as much as I like and the inverter will continue supplying the load. I only run into the issue when the inverter shuts down due to flat batteries. If feels like the inverter has some sort of logic where it's waiting for a valid grid connection before it decides to start supplying load.

1 hour ago, Surge said:

If feels like the inverter has some sort of logic where it's waiting for a valid grid connection before it decides to start supplying load.

I can't recall exactly, but there is a setting which determines what the minimum SoC would have to be for the inverter to supply power, when off-grid and at 13% as in your attached photo, I'd say its too low, maybe look for the setting that ties in with this...

I used to run a Sunsynk 5kW, without grid, period and yes, pain in the A, when it resets or has to be switched off and on again, it can take 2 or 3 minutes before it starts generating AC instead of getting to it in a hurry, glad I'm off the all-in-one HF inverter...

I set the shutdown, warning and restart battery levels to lower than the current SoC so it's not that either. The batteries can be 100% SoC and the inverter still won't start in islanding mode.

Maybe it's a firmware bug?

@Surge

I hope it's something as simple as in this video from Keith.

https://www.youtube.com/watch?v=2vLImRBxLPo