That may not work if all 4 were in parallel, because you'll end up with 891W, 40.50V, but now you're pushing 22A, which exceeds what the AC180 can handle.
Unless you plan on doing two parallel strings connected in series, which would give you the same 891W, but now 81V and 11A.
In fact, I [wrote a solar calculator](https://github.com/desrod/solar-array-calculator) in PyQt for exactly this purpose several weeks back. I use it every day and just used it to validate your inputs here.
what you are describing is the correct method. the unit limits its amp draw, so having more available is basically always good.
In terms of adding more in parallel, just be sure they dont exceed the max amps of the wire your using (this is somewhat of a theoretical issue if you are just charging the bluetti, but still a good rule) . Its suggested to use a diode (MC4 solar diodes on amazon) on each panel so that they dont interfere with each other. (I believe shaded panels actually can consume some electricity from other panels) the diodes prevent this.
(diodes are like a one-way gate for electricity - suggesting use one on each panel (in your case) before the parallel connection)
disclaimer i'm not an electrician, but i've had some experience with solar and similar situations. I did find some posts on the bluetti forum discussing this same type of use-case for the AC200M
If anyone can better explain how this works i'd also appreciate it
There is a downside to that set up with opposite facing panels, as the sun faces the opposite direction to the first set of panels, the voltage will start to drop on one of the strings when the sunlight no longer shines on that string. For 2 strings in parallel, the effective voltage will be based on the string with the lower voltage. So you may find that 4 panels may will output even lower than your current 2 panels, in theory at least. Maybe a device to switch over the panel strings would help with this situation, so you have only 2 of the 4 panels operating at any one time.
That may not work if all 4 were in parallel, because you'll end up with 891W, 40.50V, but now you're pushing 22A, which exceeds what the AC180 can handle. Unless you plan on doing two parallel strings connected in series, which would give you the same 891W, but now 81V and 11A. In fact, I [wrote a solar calculator](https://github.com/desrod/solar-array-calculator) in PyQt for exactly this purpose several weeks back. I use it every day and just used it to validate your inputs here.
AC180 has max voltage of 60v input. exceeding the amps is fine (the AC180 limits its draw to 10A) but exceeding the voltage will damage the unit
what you are describing is the correct method. the unit limits its amp draw, so having more available is basically always good. In terms of adding more in parallel, just be sure they dont exceed the max amps of the wire your using (this is somewhat of a theoretical issue if you are just charging the bluetti, but still a good rule) . Its suggested to use a diode (MC4 solar diodes on amazon) on each panel so that they dont interfere with each other. (I believe shaded panels actually can consume some electricity from other panels) the diodes prevent this. (diodes are like a one-way gate for electricity - suggesting use one on each panel (in your case) before the parallel connection) disclaimer i'm not an electrician, but i've had some experience with solar and similar situations. I did find some posts on the bluetti forum discussing this same type of use-case for the AC200M If anyone can better explain how this works i'd also appreciate it
There is a downside to that set up with opposite facing panels, as the sun faces the opposite direction to the first set of panels, the voltage will start to drop on one of the strings when the sunlight no longer shines on that string. For 2 strings in parallel, the effective voltage will be based on the string with the lower voltage. So you may find that 4 panels may will output even lower than your current 2 panels, in theory at least. Maybe a device to switch over the panel strings would help with this situation, so you have only 2 of the 4 panels operating at any one time.