Wrong MC4 connectors on AC50S or 120W Solar panel

I recently received my AC50S and Bluetti 120W solar panel. Unfortunately, I’m unable to connect them because they put the wrong connectors on them. The positive connectors are both male and both negative connectors are female. Anyone else run into this issue?

I think you are confusing what is positive and negative on the connectors. Unless you have checked with a meter and verified that the positive and negative are not correct, just snap them together the way they will connect and you will be fine.

I figured the the “+” and “-“ symbols on the connectors would be a clear way to identify positive and negative but I suppose that could be incorrect as I’m not an expert. Is Bluetti going to honor my warranty if something goes wrong when I plug the “+” cable into the the “-“ and vice versa?


The female connector coming from the panel is the positive connector. It would be impossible for all of the males to be positive because they could never connect to a female connector. Coming from the panel the female connectors a positive and the male connectors are negative

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I understand it would not work if all the positive connectors were male. I was just hoping to confirm something didn’t get done incorrectly during manufacturing. I’m not an electrician and I’m new to solar so when I read the Bluetti manual and it warned against connecting them incorrectly I quickly grew concerned. Sounds like Bluetti didn’t use properly marked MC4 connectors this time around. However, before potentially destroying two expensive devices, I was looking clarification. Thank you for your assistance.

Here is clarification…The connectors are installed properly. The connector can be positive or negative and polarity is not gender specific

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Thank you again for your help. I will hook up the panels as you suggest. I’m looking forward to testing the devices.

Just curious how that turned out for you @chairborne33

I wonder why panel manufacturers (I have two 320watt Renogy panels that are causing me concern for the same reason) would use female and male connectors that incorrectly identify whether they are the positive or negative lines.

As it is impossible to plug the male into the male and the female into the female and I have not seen any negative follow up to this thread, I am going to trust that Scott-Benson is correct and give it a go, plugging the plug marked negative from the solar panel into the plug marked positive on the AC200P and plugging the plug marked positive from the solar panel into the plug marked negative on the AC200P. That is the only way they will actually connect and I take it from Scott-Benson’s reply that this must be an industry standard and people don’t’ really care what the connectors have printed on them because the female connector from the panel is just always understood to be positive.

Tested working! If anyone stumbles across this in the future, I can confirm what Scott-Benson has said.

@Demosthenes2010 sorry I did not see your initial reply but it looks like you have already figured out that Scott was correct. Thanks again @Scott-Benson for your help and expertise.

Hi Scott you look like an expert. I used 10awg wire to connect 3 renogy flexible panels. 3 separate wires for 3 separate panels then combined them to join making 1 wire. Renogy 3 panel connector Was the size correct? My eb50 gets extremely hot in van when running my freezer. Approx 91w. I pass thru most of day and only get 184w out of the 300w panels. Have I done something wrong? Hope I made sense. Sorry

Thank you for the kind words. In reading your post, I need to know which model of Bluetti you have. You say it is an EB50, but there is no model EB50. There is an AC50(S) or an AC200 and both of which have widely differing charging input specs.

I sounds like you are saying you have three panels and each panel has a cable (containing 2 wires) that you are combining to connect in parallel, But…if this were the case, the combined amperage of the three panels would exceed what the AC50 or the AC200 would allow. If you are connecting them in series which would be connecting so that first panel would have one unconnected connector and the last would end in an unconnected connector and those two connectors would then be connected to the solar generator then that would be workable only with the AC200 because the voltage would exceed the limits of the AC50.

So…my guess is that you have them connected in parallel as in the first example and since you are exceeding the amperage limit of the sogen with this method which may be liminting your charge. In either case, connecting three panels in parallel with a reonogy 3 panel connector exceeds the capacity. Try disconnecting one of the panels from the 3 panel parallel connector and see if the charge rate drops much. I would not expect it to.

Not sure what you mean by your unit getting extremely hot but it is normal while charging and discharging for the unit to get warm and the fans will run. If you have the AC200, there are several screens that show the temperatore of the unit. If the temperature exceeds a certain limit, it will shut off and give an error due to high temp. If that is not occurring, you are not overheating.

Overall, it sounds like you have one panel too many connected in parallel. If you have the AC200 your can use all three connected in series which will work fine. 184 watts is not too bad and even if connected optimally, I would expect around 85 watts as an absolute max input per panel in absolutely perfect sun, perfect angled and rotated panels as well as not overheated panels. If your panels are mounted to the vehicle, most of the time they are neither angled or rotated optimally and the wattage you are receiving is what is expected. 10 ga. wire is fine but you could use thinner if connected in series.

Sorry. Thank you for responding. I have them in parallel. I have two bluetti’s. One is 500w and the second is the 1500w yes you are correct warm would be a better choice of words. The 1500w is only for my freezer. It’s been 110 degrees here and my van gets warm. So I thought the heat in the van might affect it. My little one is for fans. I love both of these and hope to get the 2000w as soon as I save up money. New to all of this. I would only have bluetti. You made me feel better. I will disconnect one and dedicate it to the 500w. Thank you so much.

I see I have the same confusion as I am about to hook together my EB70 and Bluetti 120 watt panel.

Just to beat a dead horse to confirm:

My connectors from my EB70 has a male end which is embossed with a “+” and a female end which has a “-”

My cable coming from the Bluetti 120 W panel had a female end that has a “-” and is a black wire. The male end is the red wire and has a “+” embossed on it.

Intuitively I should/have to hook the EB70 male (which says it is positive) with the Bluetti panel female (which says is negative and the black wire).

I think this why chairborne33 and I are confused. It seems per the embossing and color coding that we are hooking up positive to negative but that is our only option given male has to insert into female.



Just connect the male connectors to the female connectors on both ends and you will be fine. Don’t worry about what you are thinking is positive or negative. Just connect the connectors the only way they will fit and all will be fine.

I seem to be having a similar issue to this but with an extra twist.
I have a ac50S which came with the mc4 connector connect cable the connects to the back of the battery.
That cable has a mc4 male end labeled “+” and a female and tabled “-”. My pv120 has the same opposite ends that @gmcarlmrnet had. The female end that has a “-” and is a black wire. The male end is the red wire and has a “+” embossed on it. I plugged them in opposite and it all worked fine for the first month back in August. Usually pulling around 90-95w.

Unfortunately all of a sudden it stopped working completely. I spent 4 weeks trying to get in touch with Bluetti with no luck. I eventually contacted the Amazon seller who sent me a new PV120 as I was of the impression the unit must have been faulty. Once the new one arrived I connected it the same way (only way they would connect) and still no power what so ever. My battery charges fine through the same port with the AC adaptor. I am wondering if this could be a ac50s issue. I do have 5 months left on my 2 year warranty.

Any suggestions or help would be greatly appreciated.


Sounds like you may have an issue with your MC4 solar cable that connects from the solar panel wires to the AC50. This is usually caused by a poor connection at the MC4 end.

I’m hoping it’s that easy. Thanks. I think I’ll get a replacement cable and cross my fingers.


The female connector has a male pin inside. The male connector has a female pin inside. When you have to wire up your own MC 4 cables, you will see and understand. For AC wiring, the female connector (outlet) is always the source of the power.