AC300 to Transfer Switch

It been a while since there has been an update to this thread so I thought I would give an update on how I am set up and using a protran 30A manual xfer switch while connected to grid power.

I have the two AC300 in split phase connected to the combiner box powering my xfer switch.
The xfer switch in only proving power to my 120v circuits in my home and garage.
The AC300 were having issues with the floating ground so I plugged in bonding plugs to one unit then the other. No noticeable difference if they are in one or both AC300s.
This seems to provide stability to the system when not connected to Grid power.
I used a dedicated 30A 240V plug and Bluetti cable to connect grid power to system. I started to get 025/026 errors. I then used an old 50A RV surge protector for input grid power. This seemed to have gotten rid of the errors.
The system has been stable since. It has been several weeks set up in that configuration connected to grid power.
During this time I have had the system set to PV priority with SOC at 15%. As the nights grow longer here I do find the system occasionally needing to use grid power to charge in the morning. It has been doing this well.

I will admit, my load my not be as great as many others and I am running pretty basic appliances.
But it does what I need it to do. I was able to work through the many problems with the help of the folks on this forum. So, thank you all.

My last complaint is the UPS as advertised is really working as an EPS (good luck looking that up- Bluetti calls it an "Emergancy Power Supply). Not what I thought I bought.
As I am understanding what Bluetti is telling me is that in split phase that they are an EPS in single phase they are an UPS. I see this is due to the combiner box.
I have considered bypassing the combiner box with a custom cable to xfer switch and set each AC300 in single phase to provide independent UPS solution on different phases to my xfer switch.
If I recall @twister36 may have started in this direction while waiting for the combiner box.
Please share your thought on this idea.

Hey Stinger.

Glad to hear things are working for you and that the surge protector worked to resolve those issues.

Concerning the UPS you are correct that the UPS feature is not available in split phase mode. I too have confirmed this with Bluetti Engineering… This should have been documented in the manual.

I also agree that you haven’t seen any grid charging issues because your loads may be lower. However I’ve noted that when your plugged in to the grid for charging, your capacity to handle loads is drastically reduced… And if you exceed that limit your system will die… With or without using the Fusion.

Unfortunately testing a new firmware from Bluetti Engineering for the grid charge issues my system died . I since have received a new unit and I’m back to my normal setup, which includes using the T500’s to charge my batteries directly. By using the T500, my grid can come and go in split phase mode and my system doesn’t care and continues to service loads. Thus it’s working like a UPS. I have no further plans to try to charge my head unit directly… I find the system is more stable without the grid being connected to the head unit.

For the T500s I connected my home automation to the Bluetti’s data feed and created my own rules to manage each battery independently based off their charge and solar coming in. Therefore, my home automation system now controls when the batteries are charged from the grid, but sets solar as the priority.

I posted on FB about this today.

Which home automation system are you referring to?

I’m using Home Assistant

So am I but I don’t see a Bluetti integration or add-on so how did you integrate Bluetti?

Just though I would add a successful configuration working for me.

I am using the ProTran2 10 circuit sub panel with an AC300, 4 B300 batteries and 8 445 Watt solar panels making 2 4 panel arrays (2S2P). I also had AFCI/GFCI issues when trying to charge from AC source. My electrician replaced the AFCI/GFCI breaker with a standard breaker on the circuit my AC300 is plugged into. He also rewired the neutral on that breaker directly to a bus bar (I’m not an electrician so that’s the best detail I can give you). The result is that I can charge from AC using the PV Priority UPS setting to maintain a minimum 30% charge when PV is not keeping up with usage. I no longer need to manually switch back and forth from grid.
Next step is to wire my cabin with DC lines and solder Anderson connectors to my appliances so they can be disconnected from the AC adapters and directly connected to DC circuits. There are Anderson connector fused DC switch boxes available that can be installed as DC outlets. This will minimize the inverter AC conversion loss and eliminate the DC → AC → DC conversion currently going on.

1 Like

Do you have an exterior ac shutdown switch as required per FEC 2020? I am trying to find a solution… Thanks for any insight.


Do you have an exterior ac shutdown switch as required per FEC 2020? I am trying to find a solution… Thanks for any insight.

Do you have an exterior ac shutdown switch as required per FEC 2020? Trying to find a solution… Thanks for any insight.

@Woodsman Would you mind describing in detail the problem you are trying to solve?
Is it the same as at the beginning of the thread, connecting the AC300 30A outlet to the transfer switch?

Hi @Woodsman,

I actually installed a non neutral switched Reliance Pro/Tran2 also (not knowing) because I needed an exterior box, not the interior one Bluetti sells. The transfer switch neutral and ground are bonded in main panel ( which is a problem if you try to power the transfer switch and grid charge simultaneously). I decided to just remove grid charging from my setup when connected to the transfer switch and rely on my solar most of the time. If you need a grid recharge, turning off your AC output and then plugging into the grid works for me. Using some smart switches can make this a little easier to reduce some of the manual unplugging/plugging. AC output off and grid charging works for me even with the transfer switch cable still plugged into the AC300. Further, due to the advice of Twister, I am adding T500s to my setup so that I can charge my batteries while powering the transfer switch simultaneously. This way you can keep running all the transfer circuits while getting some extra juice to the batteries during low sun periods. I like this, because it removes the need to walk outside and flips the transfer switch back over to Line every time.

If I were doing this again, I would get an automatic/remote neutral switching transfer switch.