Growatt 12kW transfer switch - dumb question

[tweekzilla]

So I know the growatt has a transfer switch to move over to grid power. Question is when does it do that and what is the consequence. i.e. if the battery needs charging from the grid does it switch the output over to the grid and then charge the batteries or does the grid supply simply get converted to the right DC voltage to charge the batteries and run the inverter (i.e. inefficient which is ok). My main concern is if I'm running say the air conditioner compressor (or any motor) and it switches over to the grid does it match the phases or not as I think that would be needed to prevent damage to the motor. Otherwise I'd need some kind of interlock which sounds like it's going to be painful to implement. Or maybe the A/C compressor doesn't care if the phase isn't continuous....

 

[FilterGuy]

I cannot say for Growatt but the following is typical of any good inverter-charger (or all-in-one).

1. The inverter charger will rout the AC-in to the AC-out when it decides to drive from the grid. However, there is always a limit to how much power it can safely let through. (I have never seen one that only uses the AC-in to charge.... but that does not mean they don't exist)
2. The Inverter-Charger will adjust it's output phase and frequency to match the grid before it does the switchover. Any inverter charger that does not do this is a very dangerous device. I can't imagine a company would release a unit that does not do this...... but there are a lot of things that I could not imagine that have turned out to be true (And I like to think I have a reasonably good imagination)
3. A really good inverter charger will supplement the AC out from the battery if the AC in is insufficient for the load.

I know from personal experience that the Victron Multi-plus does all 3 of the above.

When the unit decides to switch to AC-in will vary by device and is often configurable.
* All of them will have a setting that will switch to AC-in when it detects power on the AC-in. (This is the only option on some units)
* Some of them have options for Battery Preference vs Grid Preference.

- In Grid Preference, it will switch to grid any time it can.​

- In Battery Preference, it will use the battery till the battery reaches some specified level of discharge. This is usually accompanied with settings for when the battery is charged.​

* The more advance units will even allow battery vs grid preference based on time of day. (This is great for peak-shaving if you are on time-of-day billing)

Sorry I can not give you specifics on Growatt but I have never worked with Growatt and I find their documentation to be lacking a lot of basic info and descriptions that I think should be there.

 

[FilterGuy]

BTW: It is not a dumb question. It is a very valid question.

 

[architekt]

So I know the growatt has a transfer switch to move over to grid power. Question is when does it do that and what is the consequence. i.e. if the battery needs charging from the grid does it switch the output over to the grid and then charge the batteries or does the grid supply simply get converted to the right DC voltage to charge the batteries and run the inverter (i.e. inefficient which is ok). My main concern is if I'm running say the air conditioner compressor (or any motor) and it switches over to the grid does it match the phases or not as I think that would be needed to prevent damage to the motor. Otherwise I'd need some kind of interlock which sounds like it's going to be painful to implement. Or maybe the A/C compressor doesn't care if the phase isn't continuous....

I have a Growatt 6000T-DVM. I don't have solar, I just have 2 12.8kwh big batteries hooked up to it and I only have grid power for my supply. The way mine works, and I would presume all of the similar models they make do, is that it charges the batteries AND outputs AC at the same time. The inverter itself is getting power from the grid/AC input (unless of course there is a power outtage, then it's the battery). I don't think it's really drawing much current just to run the inverter itself, although I haven't verified. It does have a "power save" switch but I don't use that. Mainly because it's not even documented in the manual. The inverter is always "on", i.e. is always displaying the LCD screen. Unless of course I were to just move the switch to the off position. But then I also wouldn't be sending the grid AC back out to my load panel.

So for example, when I first got my batteries and they were basically empty and had to be charged, once my electrician hooked it all up and we flipped all the switches, all my devices in my critical load panel were getting their proper AC power and at the same time my batteries were being charged to the specifications I had set via the Growatt LCD panel's setup interface. It doesn't like only charge the batteries and then send AC out, it does them at the same time. Once the batteries got full, it stopped charging them and just simply routes the AC to the load panel. If I kill the master breaker supplying AC to my Growatt it instantly (instantly enough for my computer) starts grabbing power from the batteries and sends it out to your AC loads. Once I flicked the breaker back it switched back to grid in grid out and recharging the batteries at the same time. Not sure if that helps or not.

 

[PeSCaLo]

I have a Growatt 6000T-DVM. I don't have solar, I just have 2 12.8kwh big batteries hooked up to it and I only have grid power for my supply. The way mine works, and I would presume all of the similar models they make do, is that it charges the batteries AND outputs AC at the same time. The inverter itself is getting power from the grid/AC input (unless of course there is a power outtage, then it's the battery). I don't think it's really drawing much current just to run the inverter itself, although I haven't verified. It does have a "power save" switch but I don't use that. Mainly because it's not even documented in the manual. The inverter is always "on", i.e. is always displaying the LCD screen. Unless of course I were to just move the switch to the off position. But then I also wouldn't be sending the grid AC back out to my load panel.

So for example, when I first got my batteries and they were basically empty and had to be charged, once my electrician hooked it all up and we flipped all the switches, all my devices in my critical load panel were getting their proper AC power and at the same time my batteries were being charged to the specifications I had set via the Growatt LCD panel's setup interface. It doesn't like only charge the batteries and then send AC out, it does them at the same time. Once the batteries got full, it stopped charging them and just simply routes the AC to the load panel. If I kill the master breaker supplying AC to my Growatt it instantly (instantly enough for my computer) starts grabbing power from the batteries and sends it out to your AC loads. Once I flicked the breaker back it switched back to grid in grid out and recharging the batteries at the same time. Not sure if that helps or not.

How is the ups system working?
No Computer shutdown when grid goes down?

 

[gnoeld]

I have a Growatt 6000T-DVM. I don't have solar, I just have 2 12.8kwh big batteries hooked up to it and I only have grid power for my supply. The way mine works, and I would presume all of the similar models they make do, is that it charges the batteries AND outputs AC at the same time. The inverter itself is getting power from the grid/AC input (unless of course there is a power outtage, then it's the battery). I don't think it's really drawing much current just to run the inverter itself, although I haven't verified. It does have a "power save" switch but I don't use that. Mainly because it's not even documented in the manual. The inverter is always "on", i.e. is always displaying the LCD screen. Unless of course I were to just move the switch to the off position. But then I also wouldn't be sending the grid AC back out to my load panel.

So for example, when I first got my batteries and they were basically empty and had to be charged, once my electrician hooked it all up and we flipped all the switches, all my devices in my critical load panel were getting their proper AC power and at the same time my batteries were being charged to the specifications I had set via the Growatt LCD panel's setup interface. It doesn't like only charge the batteries and then send AC out, it does them at the same time. Once the batteries got full, it stopped charging them and just simply routes the AC to the load panel. If I kill the master breaker supplying AC to my Growatt it instantly (instantly enough for my computer) starts grabbing power from the batteries and sends it out to your AC loads. Once I flicked the breaker back it switched back to grid in grid out and recharging the batteries at the same time. Not sure if that helps or not.

Is the only AC connection you have from your panel to the input side of the GWatt? In other words does the inverter use the same wires to get and send power to and from the main?