AC200L PV Charging Limited To 840W

Craig1 · August 6, 2024, 10:08pm

@BLUETTI_CARE : Why is the AC200L limited to about 850W of input power from PV (DC input) after ~1 hour running 1.2kW?

Below is a chart of the DC input power the AC200L measured on its DC Input from today. It slowly increased as the sun came up, then maxed out at 1.2kW, which seems normal. However, at about 12:50PM, the DC input power suddenly dropped down to about 840W.

The chart below shows sunlight brightness and there was no significant (or long) decrease in sunlight at that time. There were a few clouds, but they moved out and the sun came back. But, the AC200L didn’t.

Ambient temps near the AC200L stayed around 22 for the entire day, so it shouldn’t be overheating.
Though, to test this, a few days ago, I did point a fan at the air intake on the AC200L and cranked up the fan to high. It didn’t make a difference with this issue.

At that time the combined battery SOC was around 50%, so that shouldn’t be an issue.

Below is the battery pack SOC breakdown. Green: AC200L internal battery, orange: B300 battery connected directly to the AC200L, blue: a second B300 connected to the first B300, which connects to the AC200L.
Note that the SOC randomly jumps up when it reaches closer to 100% I am not sure what causes this, but this is an issue for another day. I have tried calibrating one of the B300 batteries (full charge / discharge 2 times), but it didn’t make a difference, so I didn’t bother with the other B300.

both the AC and DC outputs at around this time were nearly 0W, so this should have little impact on anything.

The DC input voltage as measured by the AC200L stayed well under the 145V max, so this shouldn’t be an issue. Though, it is interesting that the voltage went up a bit near 12:50PM. Don’t worry about the yellow dashed line. That is a line I added to the chart to show the voltage at which the PV input relay clicks on / off.

I have the AC200L set to “turbo charge” mode. I tested in standard mode and it didn’t make a difference. Note that the AC input on the AC200L is not plugged in. So there was no AC input power during this entire day.

I am using 1.5kW of solar panels (which I know is technically over spec), but the theoretical PV open circuit voltage is 125V, so this should not be anywhere near the danger zone of 145V.

One interesting thing I noticed is that if I disconnect the PV array from the AC200L (shut off the main PV isolation switch), wait 20 seconds, then switch it back on the AC200L will magically go back to 1.2kW (this was done on a previous day, hence it is not shown on the charts). However, after some time, it will fall back to about 840W.
I have recently (within the last week) checked for firmware updates for the AC200L (and B300), but there were none.

Do you have any thoughts as to why this would happen? Is my AC200L defective? Is there a firmware update that could improve this situation?

If you need any additional information, I can try to provide it, so let me know.

BLUETTI_CARE · August 7, 2024, 11:07am

Hi @Craig1, Regarding the issue with your AC200L where the solar charging power is limited and then suddenly returns to normal after reconnecting the solar cables, we have a new DSP version v2098.18 that can address this. However, this version is limited to the US and Japan (100V-120V regions).
Could you please provide your AC200L’s country version, SN code, and current DSP version? We will then attempt to upgrade your system to resolve the issue.

Craig1 · August 7, 2024, 9:26pm

@BLUETTI_CARE: Thanks for the quick reply!
I have the 120V US version of the AC200L.

SN Code: AC200L2352000774061
DSP: v2098.10

BLUETTI_CARE · August 8, 2024, 12:21pm

Hi @Craig1, thank you for letting us know.
Now I have applied to upgrade your system to our IT department. They will push the latest version of DSP to your machine in 24 hours.
Please upgrade the firmware tomorrow. Please do not load any device when upgrading it.

Craig1 · August 10, 2024, 1:59am

I was able to successfully update to DSP 2098.18. I will monitor the AC200L over the next few days and watch the DC input. It looks like it will be sunny tomorrow, so I should find out tomorrow if this fixed the issue. I will report back in a few days.

Thanks again for all the help!

Craig1 · August 11, 2024, 10:43pm

After watching the DC Input on the AC200L for a few days, it appears that the DSP update fixed the issue.
The input power now goes up to (just under) 1.2kW and stays there until the sun starts going behind trees.
Thanks again for helping with this. I am glad this was an easy fix!

Emax · August 12, 2024, 2:44am

Happy to hear the software fixed your issue. I was experiencing a similar issue with my AC200Max last year. A software update fixed it also. For me, I had to unplug the PV input once each morning, and it would then work properly. This issue had only started for me after I ran a series/parallel (5S2P) PV configuration, (aka 5 in series and 2 in parallel, totaling 10X panels). I’m curious if you are running a series / parallel solar setup as well?

Craig1 · August 13, 2024, 1:05am

Interesting. I was running a 5S2P setup (2 racks in parallel, each rack with 5 x 100W panels in series) for a while on the AC200L without any issues. But when I switched to 5S3P (3 racks in parallel, each rack with 5 x 100W panels in series), that is when I started experiencing the issues. However, if I disconnected the panels and reconnected them to the AC200L, it would hold at 1.2kW of DC input for maybe 5 to 10 minutes then drop back down to 840W.
I am glad the update fixed the issue though!

rgb · August 13, 2024, 6:23pm

I think I might have a similar issue. I recently added more solar to my AC200L, it’s now 1200W. However, it seems to peak at around 795. When I turn off the solar, then turn it back on, it will shoot up above that, then immediatly drop down to ~795.
This is a US model
Serial number:
AC200L2419001601458
Versions are:
DSP v2098.15

IOT v9041.06
ARM v2134.05

Internal BMS v1043.11
B230 BMS v1018.02

Would a upgrade help?

BLUETTI_CARE · August 14, 2024, 11:16am

Hi @rgb, Yes, we have a new firmware, DSP v2098.18, that can address the issue of limited solar charging power.
Now I have applied to upgrade your system to our IT department. They will push the new DSP to your machine in 24 hours.
Please upgrade the firmware according to the attachment tomorrow. Please do not load any device when upgrading it.
Additionally, please confirm that the total open-circuit voltage of your solar panels falls within the acceptable range for the AC200L (between 12V and 145V).
Please let us know if it does help.

rgb · August 14, 2024, 1:43pm

Thanks. Looking forward to the upgrade.

rgb · August 14, 2024, 6:41pm

Oops, my bad. I was looking through the manual for something else and noticed that in Silent mode, which I was in, solar is limited to 800w. I turned on Standard mode and am now getting up to 1kw when the sun is out.
Not sure I need the upgrade now. Any other benifits to getting it?

BLUETTI_CARE · August 15, 2024, 10:50am

Hi @rgb, Thank you for letting us know. We are glad to hear that the issue has been resolved.

If your AC200L is working normally, we do not recommend upgrading. The new firmware DSP v2098.18 has not yet been thoroughly tested, so we only suggest upgrading to this version if you encounter problems.

rgb · August 15, 2024, 12:50pm

I will hold off on upgrading.
Thanks again for your help.

MJ650rzr · August 16, 2024, 1:42am

I’ve also had charging issues occasionally along with unequal discharge issues to where the ac200l battery drops to 70% before discharging my B230. Thoughts?

BLUETTI_CARE · August 16, 2024, 8:55am

Hi @MJ650rzr, We would like to know if your BMS is running the latest version. Could you click on the BMS Version icon and check? Please upgrade to the latest version if needed. After upgrading, we recommend recalibrating each battery separately, and once they all reach 100% charge, you can reconnect them. This should effectively resolve the issue.
Please follow the steps below:

Please discharge all the power (charge AC & DC appliances with the power station till it is out of power and turns off automatically);
Please charge it again, please do not load any device when charging it, and do not interrupt it while in charge.
Once the power is 100% fully charged, turn off the machine, and leave it the whole day.
Please let us know if it does help.

However, please note that a slight inconsistency in SOC is normal, and it’s impossible to maintain absolute consistency. The Battery Management System will continue to work on keeping a dynamic balance.

Craig1 · August 21, 2024, 1:11am

@BLUETTI_CARE: This isn’t a major issue, but it is something I have noticed with the new DSP firmware 2098.18. Maybe you are already aware of this, but hopefully this is helpful feedback.
When my PV input can theoretically go above 1.2kW, the AC200L limits the input to about 1.953kW, which is good. However, when there are many small clouds that move past quickly (during this time), it seems that the AC200L can’t keep up and starts “glitching out”. Sometimes it falls as low as 0W of input power (for a brief moment before recovering). Take a look at the graph below. This shows the PV input (as recorded by the AC200L today). Specifically, notice how between about 12:40 and 13:20, the DC input jitters a lot and drops rather low. This is the situation I am describing.

For reference, here is the chart from my light intensity sensor (which is within 200’ of the PV array).

It almost seems like when the cloud moves away and the sun comes back out, the AC200L knows that there is too much power available and slowly starts finding the maximum power point.
However, as some thicker base layer of clouds started taking over later in the day, the PV array could no longer achieve even 1.2kW of input power. This appears to have happened at around 13:20. After this point, the brief clouds continued to pass over, but the AC200L had no trouble tracking the maximum power point. As shown in the top graph, the power stayed at or above 500W consistently even though the light sensor was detecting lower sunlight intensity at that time.

For reference, here is the DC input voltage as measured by the AC200L. It is interesting to note that during this time (when the AC200L DC input was “glitching out”), the input voltage dropped significantly. At some points, it got close to 12V.

The battery SOC is shown below. It was not near 100% during this time. Charging does appear to have slowed around 13:00 though.

The AC output measured 0W during this time and the DC output hovered around 10W.

Do you have any idea what would cause this? Is it because I am “flying too close to the sun” with my PV array?
Granted, this didn’t last long today, but some days, if the sky is very clear and there are many puffy clouds that move past quickly, this can go on for hours, resulting in (what I believe to be) a significant reduction in collected solar energy.

If you need any additional information, let me know. Hopefully this is a fixable issue (via another DSP update).

BLUETTI_CARE · August 22, 2024, 9:47am

Hi @Craig1, We have reviewed the records. It’s true that shadows can affect the efficiency of solar panels. It is normal for the power output to be lower when there are clouds, and the degree of power reduction can vary depending on the extent of the shading.
We believe this is a normal situation and there’s no need to worry.

Craig1 · September 5, 2024, 1:34am

@BLUETTI_CARE: I have been running into another issue with the new DSP firmware 2098.18 more and more recently. Sorry to keep bugging you about this, but hopefully this can be addressed with another update.

Here is an example from today.
The AC200L does fine pulling in the 1.2kW it is rated for when the sun is shining on all panels in the PV array. When a tree nearby starts blocking some sun in the afternoon, the input power starts to drop. This is totally expected and normal. But, what is not normal is that the PV input power drops a lot - down to about 140W when there should be about 400W to 500W. In the chart below, this is observed around 15:50. To fix this situation, I disconnected the PV array from the AC200L, waited about 10 seconds, then reconnected the PV array. This can be seen in the chart below at about 15:54. After that, the AC200L shot right back up to about 439W, which is in the expected region. At this point in the day, some panels are in the shade but others are still in full sun, but after the disconnect and reconnect of the PV array into the AC200L, the AC200L has no problem pulling a lot of power out of the PV array.

It almost seems like the AC200L’s MPPT controller is locked into a particular current value and doesn’t want to budge even though the voltage is dropping rapidly (as reported by the AC200L) as shown below.

In fact, the AC200L pulled the PV input voltage so low that I saw the LEDs on my surge protection device (connected to the PV array) start flickering on and off at a rate of about once to twice per second. The AC200L was practically shorting out my PV array! This array should be operating between 70V to 100V for optimal power. Not 11.7V like the AC200L was operating at. Luckily, the AC200L’s behavior doesn’t seem to cause any damage to the PV array.

The AC200L’s battery did reach 100%, but it was still working to charge the 2 attached B300 batteries, so it shouldn’t be dropping the input power yet. And, I don’t think battery SOC was an issue here since disconnecting and reconnecting the PV array to the AC200L fixed the issue. Nonetheless, I have included the SOC chart for all batteries below. Green is the AC200L’s internal battery, yellow is the first B300 in the chain and blue is the second B300 in the chain (connected to the first).

This is not a one-off incident. This has happened multiple times.
However, sometimes the AC200L does work correctly. Here is an example from last week where the AC200L worked great (ignoring the clouds around 14:30 to 14:45). Notice that the input power slowly drops. There is no increase in PV input power - once the tree covers a panel, it doesn’t become un-covered in the afternoon, so the power should never go down and back up (unless there are clouds, but there were none today at that time)

In conclusion, it appears that the AC200L sometimes enters a “glitched” state and the only way to fix this is to wait for the next day or manually unplug the PV array from the AC200L and plug it back in. Hopefully you have a better solution to this problem. If you have any questions or need more data, let me know.

rgb · September 5, 2024, 5:59pm

I haven’t had the time to track it down yet, but I’ve noticed a similar behavior with my AC200L. Sun will be out and getting 1kw+ of power, then clouds show up, power dips as expected, but when the clouds go away, the input doesn’t rise as it should.
My DSP is v2098.15
BTW, I’m curious how you collect data for the charts you show. Is this external hardware or is it part of the data collected to the cloud?