Best Solar Panel Configuration for AC300

G’day all,
I have been watching You Tube vids, looking up info and just can’t seem to decide the best configuration for my panels to charge my (still on it’s to me) AC300 Christmas special (AC300 and 1 B300).
I have 4 Trina panels already, model SS250P-60 left over from an old project and will be installing them on the roof of my 5th wheel.
specs are
Open circuit voltage = 37.6v
Pmax = 8.27a
Output = 250w
I am thinking that 2 panels in series to each of the Aviation ports would be best. That would be 72.2v @ 8.27a to each of the AC300 Avi ports.

Does anyone have a better suggestion? I know some but have lots to learn so I am open to suggestions.

Cheers in advance

The AC300 can take in up to 150 VDC at the AV port, so if you put four panels in series, you are very close to this limit. You can use three in series. And you can connect another three in series at the second port.

BTW, I am also waiting for my AC300 and B300 order to arrive. My order was posted in September .

Thanks @Raymondjram but I only have 4 panels (not 6) and unfortunately no more roof space. Yes, 4 panels in series is just over the 150v limit so that’s a no go. I am just trying to get the most output from the 4 I have.
Am I correct in thinking the Aviation port has 2 sets of inputs? The manual shows 4 wires, pins 1 and 2 are + input and pins 3 and 4 are -. I am assuming that is two circuits. Bluetti customer service is taking a while to get back to me

I’ve been trying to figure this one out. The manual states MPPT input range of 12V-150V but each DC input has their own MPPT right? This would mean you can have that range for each set? It didn’t make sense to me that the total input watts was 2,400 but the max MPPT volatage was 150, I couldn’t get even close to that. But if you can double it, that makes sense.

I have 4 100w panels connected to my AC300 and B300 currently and it’s not really enough, at least during these winter days. I want to connect some 200w panels too, so I can have 4 in series on one side and my current 4 in series on the other. Open Voltage of the 200w panels are 27 (427=108V) and open voltage of the 100w panels are 22.3 (422.3=89.2) which is within range if each circuit can take 150V, but not in total.

Each port circuit can take up to 150 volts. So you can connect all eight panels in two series, one per port.

I understand that the manual states each port can take up to 150v, my misunderstanding (maybe) is, what does “each port” mean. I am, at the moment, only focusing on the Aviation port. That would be 1 port. It seems to have 2 inputs however. Pins 1 and 3 is a set and pins 2 and 4 are a set. The adapter cable has 4 wires. One for each of the corresponding pins.
Are these two branches treated as separate inside the AC300 and thus, be able to run 2 sets of panels (4 panels in total) each at 72.2v and 8.27a OR is this a single port and the way I am thinking of setting up the 4 panels overload the Avaition port voltage limit by combining the 72.2 x 2 @ 150.4v?

To summarize, is the Aviation port one or 2 branches inside the unit?
Plagiarizing the manual, it seems I am correct but I just want to make sure (see copied text from page 21 of the manual).

I can’t copy /paste the picture, but I think figure 4 is what I am trying to achieve.

8.2.1. Charging Method 3: Solar Panels (via 4pin aviation-MC4 cable)
● For regular solar panels:
The AC300+B300 supports two PV inputs. Each individual input supports up to
12A and the charging voltage should be between 12-150V. The AC300+B300
can achieve a combined maximum of 2400W of total solar input.
a. User can connect solar panels in series(Figure 1).
b. Connect the MC4 port of solar panels to the MC4-Aviation cable (Figure2/3).
c. Plug the Aviation cable to the middle input port on AC300.(Figure 4)

You are correct. There are 2 independant MPPT controllers in the AC300. Each can handle a 12-150 volt, 12 amp, 1200 watt input independently. The aviation to MC4 cable it how to connect to the 2 separate MPPT controllers, and yes, that is why there are the 4 MC4 connectors on that cable. So you are correct to suggest connecting two of your panels in series to each of the MPPT controllers to maximize the power available from them.

Just for additional information, when it comes to the MPPT controllers, the open circuit voltage is a critical value, and must not be exceeded. Also note that the given Voc for a panel is at a temperature of 25 degrees Celsius, but panel voltages increase with lower temperatures, so you always need to account for higher Voc values during cold seasons. The output current is more flexible since the MPPT controller will only take what it can support. Think of a coffee maker vs a table fan. Both work fine on 120 volts, but each take a very different amount of power. On the other hand, don’t plug either one into a 240 volt outlet.


Cheers @hnymann
That is what I thought but I just wanted to be sure. 2 in series to each input it is.

Thanks to everyones for their input

That’s awesome news! I was also confused as it is one aviation port and the wording was a bit confusing in the manual but once you know there are two separate MPPT controllers it makes more sense. @hnymann I’ve read up on this, good to know. Any quick metric you know of like each 10 degree is x voltage you should add on?

Normally it is possible to find the voltage change per temp change in the technical details for a particular panel, as that does vary by panel, but I have noticed that many times that information is not published on sales sites. I haven’t done enough study on it myself to know if there is a “rough estimate” number that could be applied.