Ac300 + rigid solar panels and limitations

I have AC300 +2xB300. Can I connect on each PV input 3 rigid solar panels connected in series, each panel with following specs : voltage open circuit 49.6V, current 11.3A, power 440W.
3x49.6=148.8 < max 150V
11.3 A < max 12A
The total power of all three solar panels exceeds 1200W per PV input. Can I connect three solar panels that meet the basic conditions (12A, 150V) per PV input mentioned in user manual, and whose total power (1320W) exceeds 1200W of the individual MPPT charging controller or PV input without bad consequences ?
Can it be expected that in this configuration the AC300 will pull the full capacity of 2400W through both PV inputs?
Best regards !

I have similar panels with my AC300. Unfortunately from what I’ve read, you need to keep the input voltage around 10% less than maximum stated (135V), because the panels tend to produce higher voltages at [EDIT:] lower temperatures. I run only two panels at a time (~100V) into the AC300 because of this.

(Current is a different story – if you go over the threshold, the AC300 will just not pull more than it can – no harm done.)

Using more lower-wattage panels would allow you to more closely maximize the input potential.

@recycle Small correction, at higher temps the performance decreases. Lower temps will drive up the voltage.

I have a setup with 3x 455W panels in series, VOC=49.5 each. All spring and summer all worked fine, it will be getting interesting this winter.

According to my personal theory, which will be tested this winter, VOC is important when starting up charging. Once charging is ongoing, the voltage drops significantly. Therefore once the “start charge” was succesfull I expect the panels to keep performing/charging.

If somehow the charging was interupted, and the VOC > 50V it probably will be difficult to start charging again. This is my personal theory, we will have to wait and see during wintertime.

Interesting, thanks @EchteWappie. I would love to hear how they perform this winter. I would like to go three in series if possible.

I wouldn’t tempt fate, you will go over and trip and overload/fry your AC300 as you will go over 150Volts, especially if your panels are angled correctly and no shade and it could happen around 50 degrees or so. There is a PV VOLTAGE STEP DOWN MODULE(D300S) IF it is ever in stock!

I bought new PV panels that can produce 75.6 V at open circuit. I know that two in series is over the AC300 limit, but by experimentation I covered some cells and the Voc dropped to 68 VDC. So if you can shade some cells with a dark covering, such as black plastic, you can prevent the Voc from reaching the limit. I prefer to lose some power and efficiency than buying an extra device. BTW, I never get “winter”, only spring and summer.

@wtytke All AC200p + AC300 units I have, have a cut-off at a specific maximum that is built in. The AC200p has a max. of 700W solar input by spec’s. I know my setup can supply > 1000W of input. The reading shows a max out of 707 - 715W on the AC200 units, meaning they are protected for over powering.

I assume (not tested yet!) that there is also a overvoltage protection. Expected difference between those to be a limitation for the amps and a charge-shutdown for overvoltage.

In my opinion, carefully experimenting is good; always good to know were the real limits are and how your devices react to those.

@EchteWappie I was just mentioning going greater than the Voc of 150V limit not the wattage and amps. Going over the 150V more than likely will pop/burn out the AC300. The “Overpowering” and built in protection that you mention most likely refers to the Amps which can go over the 12 amp limit and going over the wattage. If the Voc is already at 148V at 25 degrees C then dropping just a few degrees lower will cause the system to go over the 150V limit. I have 3 panels (123 Voc) that reached about 1225 watts on one leg (when 1200 watts is the max) of my AC300 (and that’s at 35 degrees C outside). Referring to Amps, the generators are protected from overpowering. But going over voltage (150V), that’s a hard limit for the MPPT’s and quite sure that is NOT protected. In fact, hanging around the 145 to 150V range over time supposedly stresses and weakens the MPPT’s based on some information I have watched/read concerning MPPT’s electronics, (similar to surge suppressors wearing down over time). However, if there is an over-Voltage charge protection on the AC300, I would like @BLUETTI tech to confirm.

The MPPT is a special shunt regulator, so I believe it must have a hardware limit depending on the design and the suppliers of the components. We need to actually see and read the component identification first, then analyze the actual circuit if we cannot get information from Bluetti directly or from the manufacturer PowerOak. But I wonder if the MPPT does have a fuse to blow if that limit is reached or passed. It is cruel for the customers if the MPPT fails and there is no way to service or repair the AC300 except for a replacement.

At a simplistic level exceeding max voltage will cause damage. Exceeding max current to a point means only the required current is drawn by the device. This is where over panelling comes from, exceeding the total power limit using more solar panels but not exceeding the max voltage to give better performance in lower solar output. It still means the max power is the devices power limit. Best not to take any risks as colder weather also increases voltage.

B300s each have their own built in MPPT with voltage limits of 12-60VDC.

I am wondering if two B300s can be charged simultaneously via their onboard MPPTs and the two AC300 MPPTs to help spread the voltage of two 1000W arrays terminated on the AC300 and two 200W arrays terminated on the B300s.

Has anyone successfully charged a B300 via the onboard MPPT and the AC300 simultaneously?

This can be done and has been discussed and suggested on this forum. You can even use the D050S charge enhancer to input 500W more into your B300 in addition to the 200W of solar.

Here’s a diagram (credit goes to Jeff Hagen) of how you can max out solar charging with B230 batteries for the AC200Max but this also applies to the AC300:

With B300 you can add an additional 200W solar input via the MPPT input port.

Hi @wtytke , Yes, our machines have over-voltage charge protection. Overvoltage protection is performed as soon as input overvoltage is detected.

Thank you @BLUETTI, what happens at that point, does a simple reboot reset the “tripped” protection or does something need replaced, if so, can it be done via non-Bluetti personnel?

yes I have charged the b300 directly at the same time as the ac300 was also inputting solar charge into it, although the b300 would only allow about 215w in via it’s own port (as measured by the auxiliary 24v battery I was using to charge it). interestingly, the ac300 didn’t register any additional input on its monitor, just the solar coming in on pv, as the direct charging bypasses the ac300. and it was a cloudy day with subpar pv input, so the grand total was not limiting…

Can we get some details on the over voltage protection that you mentioned?

Hi @JP22 , Our power supplies have overvoltage charging protection, once exceeded will be protected. Of course, it can not exceed too much, usually for a few volts. But for the grid are standard, the voltage will not exceed too much.

@Bluetti, @JP22, Hmmmm, I think there is a loss of translation of “overvoltage Protection” that Bluetti is referring to and what I was referring to. I believe that Bluetti is not referring to the PV input into their MPPT’s. Even so, they refer to just a “few” volts. I would still like to know what happens once the AC300 is tripped because of exceeding 150V of PV input (e.g. 155V) - more than a few? Does a reboot reset it, as long as the voltage gets <150V? Or, does something need replaced?

Yep, not much of an answer. Pretty sure it will let the blue smoke out. No D300S’ available for 5 months now, temps headed for low 30’s next week. Going to lose about 3 hrs sun waiting for voltage to drop in the mornings. Replacing with an EG4 in a couple weeks. AC300 works great, it has been running all critical loads for 3 months.