AC Output ((Backup) of Hybrid Inverter

[Bendesa1962]

Hi everyone. My question is about a Growatt 3000HY inverter. This is a Hybrid inverter. See the attachment. There is an AC Input where the grid need to be connected to. But there is also a AC Output (BackUp) Where needs the AC Output to be wired to? To the distribution panel? What I don t understand is The grid is also connected to the distribution panel and if the AC Output also will be connected to the distribution panel I think there would be the risc of shorcut ?

[ButchDeal]

port #2 goes to the MSP, port #4 goes to a sub panel.
They should not go to the same panel

[Bendesa1962]

hi Butch, thanks for your reply. Forgive me but what is MSP? Main Switch..Panel right. But every Subpanel is connected to the MSP.....

[ButchDeal]

hi Butch, thanks for your reply. Forgive me but what is MSP? Main Switch..Panel right. But every Subpanel is connected to the MSP.....

MSP is Main Service Panel

Without solar sub panels are directly connected to the MSP BUT (BUT!!!) when you set up solar you change that.
You need a sub panel that the bimodal inverter can run. You then connect that sub panel to the AC connection on the inverter and the inverter to the MSP.
This is how bimodal systems work.

[Bendesa1962]

Hi Butch, one again thanks for your reply. I do appreciate that a lot. I have an additional question. If I do understand you correct you create an extra sub circuit on which the hybrid inverter is connected via the AC Output (Backup)? But that means that many appliances will nut run during a drop out of the grid. Because most appliances will be connected to the normal subpanel that also is connected to the MSP right? It's not 100% clear to me

[Sunking]

Correct your Emergency Breaker Panel panel is for things like a freezer, a few lights, an outlet or two so you can charge a cell phone and watch TV in the dark. You have to pick which items you want on Emergency power so your electrician can rewire them to the new Emergency Panel. Your Inverter cannot handle your home and no way can your batteries handle it.

[inetdog]

In case you are wondering about what is actually happening inside the hybrid inverter box, the AC input goes to what is called a transfer switch. When the grid is on that AC input is connected to the hybrid inverter output (for grid tied operation) and to the subpanel (backup output.)
When the grid goes away the transfer switch opens the connection to the grid and leaves the hybrid inverter output, now working in standalone mode, connected only to the subpanel.
There is no other safe and electrical code approved way to have the backup function automatically.

[Sunking]

There is no other safe and electrical code approved way to have the backup function automatically.

I have to disagree on that one Dave. A much better and less expensive way that provides power to the whole house like nothing ever happened for days and up to two weeks or more. Does not require your home to be rewired.

[rogerdw]

Ok, I'll bite. What is this "much better and less expensive way" Sunking.

[Bendesa1962]

Hello All

I would like to thank all of you for participating in this discussion.

For my explanation and questions see the attached simple diagram please.
As I understand the explanation of ButchDeal and Sunking the situation is like this:
# 4 The AC Output (Backup) needs to be connected with a subpanel, actually a completely separated circuit. In case of grid dropout the Inverter will feed the power via the # 4 AC Output of the inverter to the separated circuit. So actually you need to wire an extra circuit in your house.

What I don t understand about this situation is the following:

The separate circuit, or Emergency Breaker Panel as Sunking calls it, runs for example only the freezer, two lights and an outlet. But the freezer normally is connected to Power Group 2 of the subpanel. You can't connect the Emergency Breaker Panel to the freezer in the power group 2 because then the seperation will shortcut.

So what do you do when the grid drops out? You plug the freezer from the outlet of Power Group 2 to the outlet of the Emergency Breaker Panel?
That sounds weird isn't it?


The explanation of inetdog sounds more practical. As far as I understood the post of inetdog it works like this:

As long as the grid is functional the internal AC Switch in the inverter is connected with the AC Grid connection # 1. When the grid drops out the internal AC Switch automatically switches to the # 4 AC Output on the hybrid inverter. The # 4 AC Output on the inverter can be connected to the subpanel so during dropout all appliances from Power group 1 and 2 can run on the batteries as long as they have enough capacity.
This sounds practical and makes sense to me although I also have a question about this situation. When the grid drops out and the internal AC Switch in the inverter switches to the # 4 AC Output via the subpanel that means that AC Power can be fed into the grid. This can lead to a dangerous situation because the Utility company thinks the grid is out of power so safe to do maintenance, but the Hybrid inverter can feed power into the grid. OnGrid inverters switch of automatically when the grid drops out to avoid this situation. How will this be avoided?


I hope to receive some more replies on my post. Thanks in advance

[Mike90250]

I don't have anything right at hand to show you, but a quick look showed some diagrams of how it's done with generators, Think of the inverter as the generator and the batteries as fuel. The transfer switch is internal to the inverter,

You go to the main power box, and find which circuits control the outlets and lights you will be needing. Those wires go to a new sub panel fed from the inverter & transfer switch,
The original circuits in the main panel now go to the Grid side of the transfer switch (keep the breakers - don't toss them out)

Grid fails, transfer switch operates and the selected circuits are now on backup power.

http://www.generatorjoe.net/html/whataboutsws.html

[SunEagle]

Ok, I'll bite. What is this "much better and less expensive way" Sunking.

Use a whole house generator sized to handle the entire loads of a home.

What the OP wants to do is an option but the inverter he has is not big enough to handle the entire home. There are other hybrid inverters out there that can be grid connected as well as charge a battery system and then supply power to the entire home if the grid goes down. The problem with that type of system is it very expensive and in the long run cost more than having that generator in place to provide emergency power backup.

[Raul]

I was under impression that a bimodal has 2 AC out . One is active while AC IN is life and the other AC out is tripped by internal ATS to inverting mode taking power out the batteries when AC IN (grid/genny) is interrupted . In inverting mode does not feed back into the grid as long as this option is set in the inverter menu. That's how mine works.

[ButchDeal]

I was under impression that a bimodal has 2 AC out . One is active while AC IN is life and the other AC out is tripped by internal ATS to inverting mode taking power out the batteries when AC IN (grid/genny) is interrupted .

Sort of. There are two AC connections ( at least some have 3). All of them are tied together when grid is working.
When the grid goes down the connection is broken and only AC output is active. This connection should be to the sub panel and the loads to be backed up.

In my bimodal inverter AC1 goes to the grid, AC2 goes to the sub panel.
Inverter is connected to AC2
When the grid goes down the connection from AC1 to AC2 is broken so that inverter is no longer connected to the grid but AC2 continues to get power from the inverter.
Yours works the same way.

In inverting mode does not feed back into the grid as long as this option is set in the inverter menu. That's how mine works.

This is a different thing. Some inverters can do this. It is not that efficient and means that the inverter is only acting as a backup device.
Most will invert and feed into the grid extra power. A lot of power is wasted in this mode.

[Raul]

Yes , you explained it better , mines with 3 AC's