AC300 + large panels + arctic

In regards to the AC300:

Sun hours are 5 in summer and 1 in winter in an Arctic climate. So, I’d like to ‘overpanel’ for additional input for some extra juice in the winter. The panels I’d like to use (to minimize the number and for other features) are Longi 550W bifacial panels.

SKT 530~550 M10-144HB
Rated Power-Pm (W)
open-circuit Voltage-Voc(V)
short-circuit Current-Isc(A)
Working Voltage-Vmp(V)
Working Current-Imp(A)
Module Efficienciency (%)

Can 2 parallel sets of 2 panels in series be used as the 2 PV inputs? And what if I wanted to overpanel to double capacity for winter with 8 such panels? Is it possible, and what configuration would function best?

You should be fine as long as the voltage doesn’t exceed 150V. However, you should leave a buffer since voltage increase when it is cold. Given your Voc is nearly 50V, probably only 2 panels in series. But then you can connect as many of those in parallel as you want. It should not harm the device to overdo al as long as the max V is not exceeded.

You can do a 2p2s setup. That would be great.

A Np2s setup would also work, but you would likely see diminishing returns for N>2, since it would exceed the max current and some will be wasted.

1hr sunlight in winter only? If that’s the case I don’t think solar will work well for you then. If you get 1hr in winter, won’t you get like 23hr in summer? Sun may be low angle, but it won’t set. In that case a 3p2s may work well in the summer. Winter, nothing will help if you only have 1 hour of sun.

I would agree that 1 hour of sunlight is a challenge for solar. Not sure it would be cost effective.

Ok, but the question is if, or how well, the AC300 can be overloaded with input. Maybe the system just shuts down or blows up with too much input. The specs say there is a 12A limit on input (but they don’t say if this is a unit limit, or a per-charger limit), and a 12-150V limit (again, unit limit or per-charger limit?), but they do not say what happens with 155V of input or 15A of input.

I only provided an example. Actually, I am thinking of 24 panels: 13,200W max. I can live fine with 6000-9000Wh/day, and I know I cannot produce this in winter. For 2-3 months, I’d be lucky to get 2400Wh/day. 15-20% efficiency. But in the summer, all input to a AC300 would be overloaded no matter how I configure panels.

It’s too bad they have such low input limits when they offer over 12kWh of battery storage. It takes a lot of overloading to sustain a system when summer and winter sun hours are very different.

Let’s say I string 24 panels in sets of 12 for the 2 input chargers. 12 in series would be 600V and 13A. This would be best for cheap thin wiring. 12 in parallel would be 50V and 156A. This would requires massive and expensive wiring.

In short, I think they are sabotaging the utility and effectiveness of the AC300 by placing such a low input voltage limit of 150V on the unit. But feel free to correct my thinking if it is wrong.

I get what your saying, I have heard others comment on the 150V input as being a little low for real world applications. I do not have the AC300 (I have the AC200Max) But from what I have read on other threads in this forum the current is a hard stop, you cannot exceed it, the charge controller limits it. I’m not sure if that’s per each input though. There may be room for over voltage but not current. One thing you could consider is keeping your panels at the maximum allowable (or slightly over ) during the long daylight season and then just reconnecting more into the system during the shorter months.

I sent this email to bluetti, and will see what they say:

I really like the AC300 because it is everything I want and need, but I am thinking that the charging inputs are too limited, and I would like to know if large panel arrays can somehow be accommodated or if there are any plans to make the AC300 accommodate large arrays.

I am fully satisfied with 12kWh of battery storage. I am fine with half of that. But I have 5 sun hours in summer, and 1 sun hour in winter (Anchorage). So my plan is to use 24 Longi bifacial 550W panels, 4 rows of 6. However, they are rated at 50Voc and 13A working current. The AC300 has 2 inputs as I understand, so 12 panels per input. 6600Wmax per input.

In series, this would be 600V and 13A. In parallel, 50V and 150A, and the wiring would be very expensive. Yet, with 15-20% panel efficiency in the winter (low sun, cloudy, snowy), I would be lucky to get 2400Wh/day, even with 24 panels. But I can live with that for 2-3 months. It’s not a major problem. The major problem is avoiding dangerous input to the AC300.

Can you help me to find a solution? Or can you offer any assurance that this kind of situation will be addressed in the future?

Thank you.

You don’t have to be concerned about over current, as long as the voltage is lower than 150v it is OK. Note that when it is cold, voltage will be higher than than Voc.

Given you are in a cold place, you should only put 2 in series, but put as many of them as parallel as needed.

You don’t need crazy heavy duty wire, as the AC300 only pulls 12A no matter how many panels you put together in parallel. So, you really only need 14G wire. Standard 10G solar wiring would be more than enough.