AC200max - combine 12V outputs for higher voltage?

Hi, I’m thinking about feeding a Hoymiles HM-600 grid-tied micro inverter from the DC output of the Bluetti, but the inverter requires a startup voltage of at least 22V.
In another thread here someone asked if the 56V on the the expansion port could be used for things like this, and apparently it can not.
But would it work (i.e. is it safe) if I were to connect two (or more?) 12V outputs of the AC200max in series, to reach an output voltage of 24V and up? I’m aware that with this kind of setup the maximum amperage of the “combined output” would be limited to that of the lowest one of the individual outputs. i.e. 10A.

Failing that, could by any chance someone recommend a somewhat efficient DC-DC step up or boost converter for the 12V/30A output of the AC200max?

I did notice the announcement of the Bluetti inverters which seem to allow comparable solutions, but it looks like they won’t come to market for another six months or so, plus I’ve already got the Hoymiles lying around.

Thanks for your help!

No, you cannot connect the 12V outputs (12V/10A and 12V/30A) in series on the AC200MAX.
If you want to use a 300W micro inverter, use the 12V/30A output, and a DC-DC converter.
I use an Enervertech 300W with a DPX800S DC-DC converter.
Advantage of the DPX800S is, you can control the power, and you can set monitoring limits, and that works very well.
(Have then a max AC output power so 180W, more is not possible, because the max input current of the DPX800S is 15A).
If you use the DCDC1224P20A DC-DC converter, then you have the full 300W power.
You can also run the DCDC1224P20A with a Hoymiles 300W module inverter with DTU to adjust the AC power.

I think I have exactly the same ideas as you.
I asked the Bluetti teams “I have two AC200max and want to power a grid tie inverter to inject power into my electrical network. Currently I am using a 12V output from one of my unit. The problem is that the voltage is low and the energy efficiency is not good. Also the power output is too low.
My goal: to increase power and energy efficiency. To do this, I would like to put several 12V output from my bluetti units in series to bring the voltage to 24V and double the power…”
Bluetti’s team answered me negatively or did not want to answer my question precisely. that’s why i didn’t try to do that
Currently i only use a grid-tie converter DC12V to AC 220V (Soyosource GTN 500) on a “Cigarette Lighter Port” of one of my AC200max. It works well and also has a wheel button for adjusting the maximum power which makes it possible not to exceed the cut-off thresholds of the AC200. I set it to around 100W.
The energy efficiency is bad : at most I only managed to get 1.5KWH from an AC200max (which was charged with 2.08KWH drawn from the grid at night to take advantage of a lower electricity price at night). The energy efficiency is therefore only 72% (AC200max DC-DC converter and DC-AC inverter are quite bad, and the efficiency of my grid tie converter is only 85%). And to do this I have automated as much as possible to improve performance: I only inject when my electricity consumption exceeds 100 W (with 2 smart plug and smart life app). When the consumption of my house is lower I cut the injection and I put the AC200max “DC” automatically off (thanks to an android phone, with macrodroid) to save more power.
I think there is no salvation: you have to wait for the bluetti grid tie converter for more power (I hope it will have better energy efficiency than the AC200max inverter) which seems to be able to be powered directly with 48V from the internal battery-cells via expansion port.

For more information on energy efficiency, read AC200MAX Battery not lasting long. (Summer Project failed!) and the excellent graphs given by m .briney - Moderator

From Mark Yue

:heart:Bluetti at the IFA show gives more information on the grid tie inverter in the following video: some characteristics and a marketing date in October in Germany.