AC300 PV Parallel Error 65

Hi folks!

I’ve been running my AC300 with 3 B300s with no real issues for a couple weeks. I have two 6 panel series arrays (6x 200W, 23VoC, 10.42A Renogy panels) that I have connected to the two different MPPT controllers via the provided PV input cable (i.e., both MC4 pairs are used). As I now want to add a 2nd AC300 and more batteries, I would like to use the PV Paralleling function and put both these arrays in parallel feeding one of the two MC4 pairs. This is because I would like to add an additional 2400W array on the new AC300 without running another two wire pairs off my roof.

I hooked up these two arrays in parallel this morning and they were running fine given the low sun today… only getting ~400W (<3-4amps). When I try to enable the PV Paralleling, I immediate get an error 65. When I disconnect, cycle power to the AC300 and reconnect the PV inputs to the AC300, I still get this error immediately.

Anyone have a clue what is going on here? Do I have to wait until I get more than the 12A single MPPT max to enable this?

Running another 4 wires off my roof is really not doable in my situation so hoping I can figure this out…

What is the max voltage of your solar array? If you want max input you need to connect the panels in series up to about 85% of the input voltage limit.

Hi Scott,

I have two 1200W arrays (138VoC and 10.42A) I’m trying to hook in parallel via two Y splitters before plugging into one of the MPPTs and enabling PV paralleling. I realize this will double the current which I thought would be handled internally by the AC300 and split across both MPPTs inside the box leveraging a single MC4 pair… Maybe I’m not understanding the purpose of the PV Parallel function…

When I even just have one array plugged in, PV parallel won’t enable without a warning and the input goes to 0W.

I also tried to connect them later in the day when I was getting about 1800 watts from both using both MPPT inputs. Still got the alert and 0W when connected.

I’m getting to the point where I’m suspecting the AC300 doesn’t support my intent and is really looking for 1500w+ inputs but a lower amperage that doesn’t exceed 12A in total…or perhaps really only meant to be used with the Step Down Transformer.

To use PV parallel mode, connect each of the two wires to a Y splitter to connect to both pairs of the AC300 MC4 connectors. This worked reliably for me (over a wide range of PV output wattages) and avoided the PV parallel error. Supposedly PV parallel mode also enables the combined pair of MC4 connectors to receive more than 24A (and more than 2400W), but I did not get a chance to confirm that in action.

Thanks Terryl,

That’s exactly what I’m using to join the two arrays at my AC300 for this test. The AC300 will go into PV Parallel Enable mode with no PV connected, but as soon as I hook up a single array or both arrays in parallel via the Y splitter, I get the Alert and the wattage drops to zero.

I’m going to try again when i have full sun and higher power but I suspect the same error will occur. I have a second AC300 on the way so will try it with that one also but I’m thinking this specific unit must not be able to handle the parallel input for some reason?

You’re welcome. You need one pair of Y splitters to join the two arrays (on the roof near the panels), resulting in two PV wires coming to your AC300. But you also need another pair of Y splitters (at the AC300) to split each wire again so that the split outputs are connected to all 4 MC connectors on the AC300. If you already are doing this and are still getting PV parallel errors, then I can’t think of any reason other than possibly needing newer firmware.

If you currently have only one pair of Y splitters, you could do a quick experiment to connect only one array to the splitters and connect the 4 splitter outputs to the 4 MC connectors on the AC300. You should then be able to enable PV parallel mode.

Terryl!!! Awesome! I’m definitely not doing that currently and that makes a lot of sense. I’ll try that today. Thank you!

That was it! Needed to parallel two arrays on the roof with two Y cables first , send down the power over the single MC4 pair and then split it again using another Y cable to both DC1 and DC2 MC4 pairs on the AC300. The errors seems to have occurred as I was trying to only use DC1 previously as I was assuming the splitting would happened internally to the AC300.

Thank you Terryl !!!

You’re welcome; glad it worked for you. I wish the manual would have explained this detail. When you have your additional arrays (for your second AC300), it would be interesting experiment to parallel three arrays to see how much power (3000W?) could be generated with one AC300 in PV parallel mode.

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@BobAZ Please check that the display if the PV Parallel Enable is OFF. There is only one condition that requires ON, and that is when the same solar array with a power of 1200W or more and an open circuit voltage of less than 150V is connected in two mppts.

…and that is exactly my use case if you read the thread. PV Parallel is working great now thanks to Terryl’s inputs.

I now have both AC300’s with PV Enable On working great. Have a 2400W array on first unit and 2400 array on second unit coming off the roof on two MC4 pairs. still not maxing out 24A so may over panel a bit for early/late day charging.

My electric water heater can be brutal on my SOC…

Thanks again @terryl

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Hello. I don’t suppose you have this drawn out anywhere that is shareable? Like a Google Slide or Google Drawing? Or at least a picture of a drawing?

How many total batteries do you have?
Are the two AC300s connected to each other?
How many total 200w panels do you now have? 4800w total right?

So I have 2400w from 6x460…split to one AC300 on the two PV inputs…for two batteries.

But I have another AC300 sitting on a shelf. And I have an unused 460.

Just trying to figure out exactly what you have done to see if I can apply it to what I have.


I’ll see what i can put together with pictures.

I have two AC300s with 3 batteries each side (6 total). My AC300 are using the Bluetti 30A Ycable to my transfer switch but they are not tied together using the communication cable. All my 240V needs are single phase so I just need the extra W capacity to spread the load across the AC300s.

Just make sure you put less than 150VoC into each MPPT controller (2 per AC300). If you use the splitter it will cut the 24A max supplied current in half into each MPPT. I have two seperate arrays… 12 Renogy 200W panels and 12 Ecoworthy 195W bifacials. I have the Renogys split into a 6S2P array (138V and 20.8A) and the Ecoworthys in a 4S3P (98V and 29A) coming off the roof over two separate MC4 pairs (4 total 10awg wires). Then I use two more splitters to go from each MC4 into two MC4 pairs per AC300. The first array will never current limit out but the 2nd does at 24A (split into 12A on the second AC300). I plan to add 3 more Ecoworthy panels at some point to get 5S3P.

The 2nd pic shows the wires for the first array coming to the AC300 and then being split to the pair of MC4 connectors.

If you are coming off the roof now with 4 wires on your first array, you can parallel those with Y cables and come off the roof with 2 wires. Then split that back into 4 MC4 at the AC300. Do the same thing for your second AC300 and array.

For me this completely powers all 10 circuits (including my 240V hot water heater) and 8 other household circuits.

I have the two T500s there to charge the bottom batteries off the grid if needed. Since the batteries are in parallel, one T500 plugged into one battery will charge both at 500W total…slow but works. Haven’t had to since added 5th/6th batteries…

I’ll eventually get this into a solar disconnect box and through the wall properly…