AC200p input pv fluctuations

I hooked two 100 watt HQST panels to the AC200P in series. In full sun the input power bounces back and forth showing 100 watts and 53 watts. I have a 30 ft extension cable between the battery and panels . Any
suggestions on why there are fluctuations?

Poor electrical contact in the MC4 extension connections? Take apart and snap back together fully to see if that solves the issue. If the fluctuations are very slow, is it just passing clouds causing shadows?

The screen readout on my AC200P fluctuates 20-30 watts almost constantly even under ideal conditions, doesn’t seem to matter what panels or cables I use. I think its just the BMS making constant input adjustments as an inline watt meter I put in before the AC200P will fluctuate nearly the same amount as well.

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Hi @Flapjack ,
When you charge with the solar panel, is there any shade on the panel? Could you send a picture of it when charging for better confirm the problem? Thank you for your cooperation

How rapid are the fluctuations? If they are slow, I would think the MPPT charging is adjusting for max input. If very rapid, that is odd.

Just checked the PV input and its fluctuating about every second in a range of about 90 watts which is more than I remembered (480w to 570w). Checked it in car mode both 12v and 24v and its rock solid, no fluctuations.

There are no shadows on the panels. The fluctuations are back in forth…I would say every half second. All connections are good. Open circuit voltage on both panels is 18, so I’m at the minimum voltage required but the bluetti screen is reading this alternating: 109 watts/3.5 amps, 31.4 V—'57 watts/1.7 amps, 33.8 volts. I am thinking that with only 200 watts of panel, I am not meeting the minimum voltage. I am testing with a friends panels …300 watts plus this weekend to see if this will solve. I saw online dome known issues people are saying you need at least 300 watts gor the AC200P.

Hi @Flapjack , The theoretical value of two solar panels connected in series is 36V, which should not be enough to power the AC200P. We suggest you add an additional solar panel and see if the screen reading still jumps. Thank you.

It is not the watts you need for charging to begin but volts. The voltage you are seeing at 31-34 is below the minimum of 35 required for charging and may be the cause of the fluctuations.

The voltage from the panels is reduced when under heavy load and increases with lighter loads. You may be seeing the voltage being high enough to charge at the beginning and then when under load, the panel voltage drops to less that the allowable minimum and the AC200 stops charging momentarily. When that occurs the voltage increases since the load is decreased and the cycle keeps repeating itself. As Bluetti mentions below, adding another panel may solve your issue.


I own an AC200P. Your culprit is the mppt controller. Volts are the flow into the generator. Amps are used by the mppt “at will” to give the volts the optimum wattage. Since the mppt uses amps to control the volts to create watts, a fluctuating response happens.

I had a learning curve myself. I bought 10-100w solar panels. The AC200P requirements are 150v/12a. Volts are more detrimental to the generator. The solar panels specifications are 21.6v/5.76a. Using watts law V x A = W, a 6-100w panels in series gives 129.6v/5.76a. 1 more panel takes it just over 150v at 151.6v. How frustrating!!!

Important results:

“Volts are more detrimental than amp to the generator”.

With 6 solar panels at 21.6v/5.76a the volts at the mc4 connectors were actually 132v. 1 more panel is over volts at 153.6v, the Mppt triggers off.

Series=combined volts
Parallel=combined amps

Using 10awg (15amp rating) solar wires, 8 solar panels in a 4-series/2-parallel configuration gets 86.4v/11.57a. That fits into the AC200P specifications, with lower “detrimental volts”. Using watts law(VxA=W), you get 86.4x11.57a=978.82 watts. Hold on WHAT!!! Yes its :slightly_smiling_face: fine. The specifications are 150v/12a. My MPPT controller energy loss is about 30%. Because of the length of my 10awg wire length. It runs an average of 666.86w. The bluetti AC200P will only accept 700w no matter how many panels. Its the specifications of 150v/12a thats important.


  1. 2 sets of 4 in series, connect each series into a double parallel T-branch.
  2. Connect your 10awg wires leading to the AC200P into the single end of the double branch connectors to the aviation plug.

Secondary solar/ac input:
MC4 connector to D050S to secondary ac plug.


The mppt degradation of 34% and the 50v/10a DO50S requirements of (50v/10a) connecting 3-100w panels is way over 50v. Using 2 panels in series with a 34% mppt degradation gives only 134w.

AC200P+B230= Storage 4,000w:
Find the highest watt 1 or 2 series panel configuration. I personally use a 400w and get 264w.

My total average watt production of my solar array is 900w.

7.0 cubic freezer, mini fridge, refrigerator and a 50" LCD.


  1. 750w water purifier at 4 hrs
  2. Nuwave oven 30 min.