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EG4 18Kpv - Why connect Load wiring when Grid feeds back?

rushth

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May 6, 2024
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5
Location
Illinois, USA
What am I missing out on by not connecting the Load side? Right now I have the Grid connected to a 70A circuit breaker in my panel, the CTs are right after the meter. Everything seems to be working fine, with the inverter supplying back fed power to the panel.
I understand I won't be able to separate my loads when utility power goes out, but is there anything else that I'm missing?
 
I would recommend reading the partial home backup with backfed breaker diagram from the manual. This goes over the main disadvantage of this setup.


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Jared, thank you...

I've seen this page in the manual, but it still doesn't cover my setup. I don't have anything connected to the LOAD terminals, just GRID.
It doesn't cover my wiring setup and I haven't seen anything online about it.

Would you happen to know if wiring into the Main panel only would work? And what are the drawbacks?
I did notice that my consumption power is about 300 watts below actual when comparing it to my Emporia readouts.
 
The primary drawback is that if the grid fails, you would be unable to power loads/net meter and would not be able to utilize the 18k's capability to pass through a full 200A from the grid should you decide to add a critical loads panel.
 
You can use the inverter without a backed up loads panel as GT PV inverter only, or PV + battery for peak shaving and time shifting. Other products do just that, unless they have external transfer switch. 18kpv is an all in one, can do any or all the functions itself.

Presumably you would like something powered during blackouts, if only internet router and minor appliances. You might power that with a (fused) connection to power string and power cords, doesn't have to be hard wired.
 
This is great, thank you for the info.
So there would be no way to automatically turn on the LOAD output during power outage? I would need a transfer switch to toggle between LOAD and GRID for my main breaker panel.
The reason for my question is that it would be easier and cheaper not to have to run a second set of wires for the LOAD circuit, I also wouldn't have to install a second critical loads panel.
I guess I could always tie GRID and LOADS together and keep the LOADs CB off. Then if power goes out I turn off the Main panel CB and turn on LOADs. But that's not ideal. And what happens if both LOAD and GRID are turned on at the same time? Do I fry the inverter?
 
Since the 18kpv includes a transfer switch, you can run mains to it, and have it feed your main panel on the loads circuit.
That way you get up to 12kW of standby power on your main panel.
 
No, an AIO would power LOAD output by passing through grid or from inverter. Might be a brief glitch, unlike some UPS.)

But I would set up critical loads panel fed by AIO, and also with second interlocked breaker fed from grid.
Inverters can fail, and you want to just flip a couple breakers to restore power using grid.

Yes, shorting LOAD to GRID fries the inverter. Or electrocutes the lineman.
Always use a UL Listed transfer switch or interlocked breakers to ensure only one at a time is connected.
 
Thank you again for the info.
Looks like I'm buying a subpanel and running extra LOAD wires to it.
Transfer switch is an option, but I do like it being automatic in the event of power failure when I'm not home.
 
And what happens if both LOAD and GRID are turned on at the same time? Do I fry the inverter?
The problem is when the Grid is down, and comes back on. The Grid is out of phase with the Inverter, and that creates the "fry". Inverters with internal isolation circuits (18kpv on the Grid Line), the inverter watches the grid line, when it comes back up, it syncs to the grid line, and then reconnects. It also waits for a period of time for the grid to stabilize before reconnecting.
 
I guess I could always tie GRID and LOADS together and keep the LOADs CB off. Then if power goes out I turn off the Main panel CB and turn on LOADs. But that's not ideal. And what happens if both LOAD and GRID are turned on at the same time? Do I fry the inverter?
Put a breaker interlock on the Main Panel, so that the Grid and Inverter cannot both power the Main Panel at the same time. Something like this:

During grid down, you can manually switch to power from the Inverter. You probably also need a breaker interlock between the Grid and Load input to the main panel:

Otherwise an Automatic Transfer Switch is required where the Inverter takes the place of the Generator. But at that point, you might as well wire in the 18kpv between the Meter and the Panel.
 
I'm also seeing an issue with the reported Consumption power and Grid draw accuracy. The 18Kpv is showing no grid draw, but my Emporia Vue shows between 300-800 watt net usage from the grid. I wonder if wiring in the LOAD side will help with the accuracy.
 
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