AC200 + 2 bluetti 120w panels, no charge

Hello all, I was hoping i could pick someone’s brain about my setup because im out of ideas.

So i have 2 bluetti 120w panels, in series. Hooked to AC200.

Problem is, even under full sun (like right now) or on a cloudy day, partial shading or not. The panels are registering the same range of values. Nothing that could even come close to charging this thing. In fact the panels are causing my charge to go down. (Nothing else is hooked on the AC200)

Started at 90% battery, now at 84% and still going down.

Input: (full sun or not)
31.4 volt - panels in series
0.0 amps or 0.7 amps - if im “lucky”
12w or 32w- never goes higher
Gen energy: 0.0 kw/h
Temp 16c / 60f (also tried when temp is a bit higher, no change)

Any chance someone could spot what am doing wrong with that info? Or is that all this thing can do with 2 panels ?

Assuming the AC200 is “registering” the 31.4 volts on the main screen, It sounds to me like there is an MC4 connector issue that is either not making good contact or the wire has come loose. The first thing I would do is unplug and connect tightly all the connectors again and see if there is a difference.

Second thing would be to take a volt meter and record the voltage of each panel separately in the same sun conditions side by side. They should be similar and if not this should narrow down the problem connector. If a difference is noted, unscrew the end cap on each MC4 connector and verify that the wire is firmly attached and not hanging by a thread.

Third, if both banel read well, inspect the MC4 connectors on the MC4 to XT90 connector for loose wires and lastly, inspect the XT90 to aviation input cable for loose wiring. The aviation connector unscrews from the end for easy inspection of the the connections. If you have any extension cables, connect the unit without the extension cables to see if that makes a difference. If it improves dramatically, check the extension cable connectors.

If all the wiring checks out, I would suspect one panel not outputting properly. You should be seeing 37 to 40 volts of output and in perfect sun around 180 to190 watts. You will lose a good amount of wattage in any overcast or cloud situations but the volts should still appear. Panels connected in series cannot have any shading (grass, plants, cable shadows etc) or you will lose charge.

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Thank you for this very helpful answer. I will check all that asap and post back. Hopefully it’s not a big defect. As for partial shading, I don’t think I have a choice to connect in series with these panels, voltage would never be high enough otherwise (if i understand correctly). So I havent tried parallel. But if the issue is partial shading, I don’t understand how this setup is even worth mentionning since it’s impossible to have direct sun and no partial shading long enough to even get the charge go 1% up. Maybe my eyes were just bigger than my stomach hehe.


i don’t have a multimeter yet. But i tried some things.

I connected both solar panels (to the AC200), one by one, to see the registered voltage for each panels.

Panel A alone, no extention: 24.3 v
Panel B alone, no extention: 24.6 v

Now i use a splitter to hookup in series. I tried a different spiltter this time. (To connect pos from panel A to neg panel B) and i have better results now. (I don’t have any extensions, just minimal wiring obtained from bluetti. Only the one splitter is thirdparty)

Panels in series test#2:
Input: (Sunny but not optimal conditions)
35 to 42 volt - panels in series
1.3 amps to 1.9 amps
50w or 90w- so far
Gen energy: 0.0 kw/h
Temp 18c / 64f

Seems like the charge still going down though


After a while longer same setup as test#2, i noticed that the voltage dropped again. To 31v. It was at around 40v for 30mins just before the drop. I havent touched anything for the drop to occur. At first, I thought the clouds were causing the drop. But, while the clouds were still blocking and the voltage was back at 31v, i unplugged the aviator connector and plugged right back in. The voltage went back up to 40v. Im not sure how to make sense of that lol

But I did gain 1%! From 82% to 83% haha. Don’t know what’s going on but I hope I won’t have to constantly plug and unplug my setup to prevent the voltage to keep going under minimum requirement


Not sure what you mean by “splitter”. To connect in series, you should connect one wire from one of the panels directly to the only wire on the second panel that it will mate to. This will leave you with a single unconnected wire from each panel. Those can connect directly to the MC4 to XT90 bluetti cable which then connects to the aviation cable and then to the AC200 input port. No other items are required to connect unless you need extension cables.

When you are connected in series and blockage or shadowing of a portion of one panel can affect the other panel and other portions of the panels. I am assuming your panels are outside and you are aiming them directly at the sun etc. If not, a picture of your setup may assist.

Oh my, I have no idea why I was using the “splitter”. But I removed it from my setup and the readings on the voltage is a tad better than test#2. It varies rapidly from 33v to 40v but there is not a single ray of sun outside anymore (1h46pm clouds everywhere)

Panels in series test#3:
Input: (mid afternoon, just clouds, no sun)
33 to 40 volt - panels in series, no splitter
0.5 amps
Gen energy: 0.0 kw/h
Temp 17c / 62f
Battery now at 82%

I threw the panels on top of my car windshield for now. It’s right next to a building so the sun is always blocked. I wanted to simulated the worst conditions possible to see if i need more panels.

Anyways i’ll let this run a while and see, but looks normal. I guess I was just a dummy for forgetting to take the splitter off

Edit: trying to post pics. Ok i added “one” pic per previous post. But confirmed now, even with this careless setup but no spiltter, the battery charges now. Even with crappy readings like test#3. Thank you! I think i’ll get one more panel

The bottom line is that if you don’t have the ability to receive clear sunlight, you will not get much charging. The panels rely on clear sun, correct angling to the sun (perpendicular to the sun) and also moving the panels to keep the orientation during the day. If one part of a series connected panel gets shaded, it slows or blocks the electrical flow through the panel. Kind of like if you are tied to a group of marathon runners and a 300 lb person with one leg, you can only run as fast as the slowest person.

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Nice analogy haha. But I get it. For now I am just having fun testing. But those tips will sure come in handy later :slight_smile:

As for my initial issue, seems all is well now. This afternoon is as cloudy as it gets here… still charging a little hehe.

Thanks for the help!

Well, not long after my last post the voltage went back at 31v and is still in this range since then. I’ve tried unplugging the aviator plug and then back in. That gave me 42v momentarilly (20 secs or so), then steady 31v and stays there. I guess I will try again once more sun comes out.

I am not expert. I have 6 180 v Bourge RV panels hooked in series for my AC200P. 4 also does a good job but 2 of what you have I don’t think will work well… Good luck

@mgagnequebec & @shawnnn99 I can confirm that 2 of the sp120 panels in series will work for the AC200. I couldn’t find a pic of the multimeter readings but the voltage def is within the 35v-150v requirements when connected in series.

I live in Michigan and these pics were taken back in early November, just before the snow started. so def not “optimal” conditions haha but the AC200 was pulling in 191w steadily.

I just want to add, now it is full sunny. No partial shading. Positionned the panels best I could. But I was getting 40v + for 10 mins. Now back to 31v at it won’t budge. the sun is still directly shining on the panels for this test.

What’s even more weird is that i’m still charging. Nothing is hooked to the ac200 (except the 2 panels) and no extentions.


From what I have seen, your issue is most likely related to where you have your panels since they are not exposed to clear sun or tilted and aimed appropriately.