DanB, could you share how you wired your setup? I think this is how I’d like to do mine as well.
I have 6x210 solar. These enter my home through a 4 prong entry box. 5 of the panels in series go to the ac200, one goes to the charge enhancer (I plan to add 2 more panels to the enhancer). The sub panel, which is on the exterior of my home, is fed AC power through the wall via a 20 amp ac port mounted to an exterior electrical box. I will try to get a photo of the exterior boxes. The sub panel and transfer switch were installed by the prior owner of our home for use with a gas generator. It has a mechanical switch which I hooe to change to some sort of WiFi switch, but I can’t seem to find a suitable such switch. (Any suggestions?)
I received a replacement AC300 today, and it too is exhibiting the same issue as the first one when I am connected to the transfer switch…
I have found a work-around. It’s imperfect, but also offers an advantage…
Instead of plugging the AC300 into the wall, I hooked it up to a DC charger (e.g. T500) through one of the DC-input ports. Turning the gird power on and off keeps the inverter on at all times when connected to the transfer switch, preventing the error from appearing.
I believe the error pops up when the unit switches from the inverter to the AC bypass, thus you avoid this scenario entirely.
This approach has some disadvantages: since we are not using the bypass, the inverter is on all the time, and the battery is constantly charging/discharging. This is typical for an “online” (vs offline) UPS though (eg the EP500 has this mode). It’s also typical when you have solar panels. Second the charging input is limited to your charger, although I think you can hook-up multiple DC chargers if you wanted.
There is an advantage though: you can get the full 30-AMP, up-to 6000 watt output from the battery, that you can’t get in bypass mode (where you are limited to whatever the socket providing power to the AC300 is limited to, typically 15 amps, ~1800 watts).
I still hope Bluetti can fix the original problem (and maybe this provides a clue), but this provides a “back-door” online UPS solution.
1 Like
I don’t have the T500 so am trying to understand. By “DC Input ports” do you mean using one of the two DC/PV MC4’s, or are you going Wall AC->DC T500->AC input of AC300? Curious because I have both DC inputs running from my roof solar and that doesn’t solve it despite power coming in on the DC side.
I’m actually waiting to receive the T500 I ordered, so in the meantime, I hooked-up this 120V to 12V charger from Amazon, and used the car-charger plug that came with the AC300 to plug it into one of the MC4 ports.
Kind of surprised the solar panels don’t do it for you though. Is the inverter on? Have you unplugged the AC300 from the wall?
DanB, thank you for sharing. I think this is how I’m going to hook my system up initially (Solar input, transfer switch output).
I know you can get an automatic transfer switch but I haven’t found one that has wireless control for turning on and off.
You got me thinking here since you’re basically bypassing the AC (grid) input on the unit. Anyone here know if this idea would be safe…
- Use a Y mc4 splitter cable off one of the two dc inputs on the AC300.
- Run one side of the split to solar panels in series (all under 150 volts), and the other split run to the AC300 car charger cable to a 120V to 12V charger like @recycle used above.
- Use an Alexa plug on the 120V to 12V charger to turn on the 120V to 12V charger from sunset to sunrise… therefore the panels wouldn’t be generating electricity, but the charger would kick on trickle charge during the night and stay under the 150v on the DC input.
- Unplug the AC grid input cable from the wall… so essentially run entirely through the DC inputs of the AC300… and no longer worry about grid power going off or on since, to the unit, it will just look like DC coming from panels.
Any safety issues with this? The solar panels are in series… so would a set of panels in series on one side of the mc4 split, w/ the 120V to 12V converter from AC grid on other side of the mc4 split, into one of the AC300 DC inputs, be safe?
I see no problem with that setup – even the AC300 user-manual says you can hook up a charger and PV into the DC inputs simultaneously. (Note that the “split” cable is really feeding the two independent DC inputs separately – it is a little odd they use that cable instead of having two ports.)
You could even use both inputs of the split cable for PV and plug the charger directly into the B300 battery for more flexibility.
I’ve been using this “online” UPS hack for about a week now and am very satisfied with it. I found another advantage: when using the standard AC input, when the AC300 switches the bypass on-and-off, there is a 20ms loss of power to your devices. I find that’s too long for some devices (e.g. my router, desktop computer, Apple TV), and causes them to power-cycle. Using this approach, they stay live so no reboots or loss of data.
I think even if Bluetti finds a fix for the bypass problem, I will probably stick to this approach.
1 Like
“You could even use both inputs of the split cable for PV and plug the charger directly into the B300 battery for more flexibility.”
Does the AC300 “see” the input coming from the T500 on the B300? This might actually be the best option if that would work… since I’d get 500W grid input (that I could turn off/on w/ alexa plug), or during outage run from my EV’s inverter, AND I’d have PV as well. I guess the only thing that wouldn’t work is the UPS modes on the AC300 since I’d have to manually turn of/on the T500 as needed?
An Update on the issue of the AC300 ac inverter turning off when power is lost and returns from the ac power of the unit.
I sent videos and explained the situation to service but they have not been able to determine the cause. They asked that an RMA be issued and for me to send back the ac300 for them to look at it. I just dropped the unit off to UPS ground. I also made a new video for them to closely review. Here is the link if you are interested in seeing the results of my tests.
I was asked to return mine as well. I’m trying to avoid that and purchased the T500 (arrives next week) to see if that at least gives me a workaround. I’m not convinced a new unit will fix this issue. Are you getting another AC300 that you’ll be able to attempt with?
They will send me another ac300. I don’t expect any difference. I am using the Ac300s as back up and not planning as ups live. Even if the ac inverter shuts down, can turn it back on using the app. No big deal for me. I just wanted to see the product work correctly in case of future needs.
I returned my original AC300 and got a replacement that behaved exactly as the first.
Note you can’t turn the AC output back on from the app (I had the same idea) because you have to clear the alert first which can’t be done from the app.
Oh… you are correct. Did not consider that the alarm would still be outstanding. I only remember seeing the on/off toggle on the app. I hope support is reading this thread. The app needs more abilities. Clearing the alarm is one. Remotely powering on and off the ac300 is another. I mentioned somewhere else that using a wifi outlet, you can remotely turn on the electricity and the unit detects power from the ac power chord and turns on. However there is no ability to turn the ac300 off remotely after. Once it is remotely on using the wifi outlet, turning off the outlet does not turn off the ac300 if the unit still has battery power.
If there is no charging power coming in, and the AC and DC outputs are all off, then the unit will power down after some time, maybe 4 hours? I’ve had my AC300 turn off over night in those circumstances. It turns back on when the solar panels get sun in the morning.
Thanks…
Nice to know that at least you can turn off the ac power using a wifi outlet and then through the app power down the dc and ac inverters and have the unit go into sleep/shutdown mode in a 4 hour time frame to save battery consumption.
1 Like
Well, after my unit died, I sent it back and they are sending me a new unit which I appreciate. They did say don’t use it with a transfer switch. I’m not totally happy with this.
The main purpose of me owning this is for the home and not using it with a transfer switch isn’t awesome (nor was there concerns documented in the product documentation).
Isn’t the smart home panel just a fancy transfer switch?
https://www.bluettipower.com/products/ep500-ups-boxsub-panel
So I was showing a friend of mine who is an Electrical Engineer what was happening, and he has a pretty good theory what the problem is…
When the power is restored to the AC300 after an outage, it switches to “bypass”, sending power directly to AC outputs. This is probably done with a relay or something similar. The process of sending power anew through there will usually cause a voltage spike (just like if you watch an outlet spark when you plug something in). There has to be some kind of surge suppressor to prevent dangerous levels of spikes. It is probably tuned for a typical range of voltage spikes that you would expect for devices plugged directly into the AC300.
However, a transfer switch is capable of generating a much larger voltage spike when connected, even when no current is flowing, because it has much higher capacity wires running directly to the panel. He suspects their surge suppressor is not tuned for these larger voltages. This would obviously be consistent with the error we get (high bus voltage), and also the fact it sometimes works (sometimes spikes are small).
I asked him if he thought the suppressor might be software adjustable. His answer was “something along those lines would be 10x or more the cost of a simple suppressor, so unless there was some other need for it, highly unlikely”.
The arc you see when you plug in a plug tot he wall is called arcing. The voltage should be constant (or even dropping due to inrush current) though so I’m very doubtful your friend is correct (My dad is an electrician and my formal degree is computer science with some electrical engineering work).
You have to remember as well that this works until you simulate a power failure (I.e. the switch from off to grid power works fine, the switch from grid to UPS power works fine when the power failure occurs, it just fails when the power is restored.
I’m done running tests after one of my AC300’s blowing up due to this but an interesting test is probably running the AC300’s in split phase with a generator that is not ground/neutral bonded to the AC300’s and then simulate the power failure with that method.
Without really knowing the root cause of the problem I do believe bluetti could solve this. Clearly the case works fine where we switch the unit on when grid is on and clearly the swap to battery power works fine as well. It seems that by increasing the software delay between power restorations, detecting it occurred that they could delay the relay switch longer. First swap the inverter off and return this to being the base case of powering on when the grid is on. Yes, you would see the power blip and some devices would probably reboot but it’s less bad than what is occurring now.