AC300 Solar Efficiency 50%?

My AC300 appears to be defective. I have 1600w of solar panels, setup in two strings. Using a multimeter, i measured each string, and they produce 84-87 volts and 8.6-9.1 amps, about 750w each, 1500w total, on a sunny day. However, I never see more than 750w, usually less than 700w. When I turned PV Parallel Enable to ON, this caused a 065 PV Parelleling error. I’m getting HALF the production I should be. I’ve sent a couple emails about this to support but have not received any response. Anyone else have this problem?

Hi @DavidKim , sorry for inconvenience caused.
The following questions need to be confirmed with you.
May I ask you the specific parameters of your solar panel? 1600W contains how many panels of the same specifications?
And about your PV Parallel Enable, you don’t need to turn on this option, once it is turned on, it will report an error, just turn it off.
Looking forward to your updates.

I’m using 16x 100w panels. Each panel has an Open-Circuit Voltage (Voc) of 25.9V and a Short-Circuit Current (Isc) of 4.9A. I have them wired in series in groups of 4. Two groups are then wired in parallel for each controller, DC1 and DC2. That makes the max Volts 25.9x4 or 103.6 (i typically read 84-87v at noon on a sunny day with a multimeter) and a max of 9.8 amps, 4.9x2 (I’m seeing 8.6-9.1a with a multimeter). This is all within the specs for each controller and I’ve checked multiple times with a multimeter

Have you tried running the DC1 and DC2 inputs each alone to see if one of the controllers is bad?

Interesting. No i havent. Ill try that now

Ok, yeah, when i only connect DC1, charging rate goes down to half of what it was. When i only connect DC2, same thing. So whatever the problem is, it appears equal for both DC1 and DC2

1 Like

Hi @DavidKim , Thank you for your reply. May I ask.

  1. Are your DC1 and DC2 set to PV mode?
  2. Can you see what the voltage and power of PV in this interface is?
  3. 100w panels connected in series and parallel will increase the loss of wire diameter, do you have other high-power solar panels to try?
  1. Yes, both are in PV mode
  2. I’ve listed the volts and amps twice previously. Each input is getting 84-87 volts and 8.6-9.1 amps. This is at the END of the cable right where it connects to the adapter into the AC300
  3. No i dont have other panels to try. Ive measured the power at the end of the cable with a multimeter. Its over 1500w on sunny days. But the AC300 is showing less than 800w. The loss is all in the AC300

Hi @DavidKim , thanks for your feedback.
Our engineers are already working on simulations of your machine situation. Once we have the results, will inform you. Thank you for your patience and understanding.

Hi @DavidKim , The above two videos (Uploading via wetransfer, please click the above link to view) are simulated experiments of AC300 charging with PV according to your data, and the power is normal. The first video is connected to 2-way PV, 1200W. The second video is only connected to 1-way PV, less than 800W. We would be appreciated if you can share us a video feedback on the operation of AC300.

What? How would a video help at all?

I will make a recording the next time we have a sunny day. But the measurements i made are at the end of the cable from the solar panels with a multimeter. It measures volts x amps, and its around 1500w. The loss is all in the AC300. THIS IS DEFECTIVE

Can you tell us the voltage that you are getting from the multimeter at the end of the MC4 connector and what the AC300 is reporting as voltage?

Also how are you measuring current with the meter? Do you have it in line between the connector and the AC300?

How many times am i gonna get asked the SAME question? Im using a multi meter at the end of the cable from the solar panels. Its measuring 8.6-9.1 amps on sunny days. I have not had a sunny day since i was asked for a video to see what the AC300 is reporting. I will do so once the rainy days end.

No worries mate. Just trying to help.

I’ll keep quiet from now on. Sorry for the inconvenience.

1 Like

Sorry dr_torch, i didnt see that you werent Bluetti support. This has been going on via email and chat as well, and they keep asking me the same questions, to the point im literally copying and pasting my answers. So, i was way too quick on the trigger here and that wasnt intended for you. Ive got one support person literally telliing me i shouldnt connect my solar panels in parallel even though im showing her that its less than 9 amps per controller. Its been an extremely frustrating experience dealing with Bluetti support



I got a new PV input adapter from support and it did not fix the problem. In fact its gotten worse. I checked the input values by hitting the PV circle on the touchscreen and took a screen shot. The values are FAR below what the multimeter is reading from the end of the cable that goes into the AC300.

@DavidKim This might have to do with the way you measure the voltages…

The system screen shows the voltages under load. If you are measuring the panels + / - straight for the panels, meaning not under load, you are measuring what is called VOC. This voltage is by defenition higher than the voltage under load.

I’m not sure about your exact measuring/setup, but this comes to mind.

@EchteWappie are you saying less than 800w from a 1600w system at 1pm Pacific Daylight time (noon standard time) on a clear sunny day is a normal expectation? I didnt even bother putting on the aligator clips to test amps this time, but those are are also way below what the I’m getting on the multimeter. Bluetti support already approved a return and refund, so this unpleasant experience is about to end for me

No, that is not what I’m saying. I was comparing voltages, not power output.

Your multimeter shows voltages to be different than on the display of the unit. I only stated a possible reason why these readings may differ.

Good to hear that Bluetti accepted the return/refund of course. But it might have been interesting to see how a new replacement would have worked out.