A few follow up question for Bluetti, based on Craig1’s observations: What is causing the PV input voltage to remain low after the shading has passed and the panels are in full sunlight? Is the MPPT also applying its own voltage to control/balance the charging rate from solar by reducing the potential difference in voltage? If this is the case, then what is the AC200L actually reporting for voltage in the PV screen of the app? Is it what is coming in from the panels, or is it what is the remaining voltage after the MPPT does its thing?
@rgb: I am using a program I found from ftrueck called bluetti_mqtt (GitHub - ftrueck/bluetti_mqtt: MQTT interface for Bluetti power stations). It integrates the AC200L and other Bluetti products into Home Assistant, allowing one to view the output power, input power, control the AC output, DC outputs, and more. Essentially, it simulates the app and acts as a middleman to allow Home Assistant to communicate with Bluetti products over bluetooth. However, I don’t run Home Assistant, but I do manage an Influx DB for another project. It was an “experience” hacking that code to import the data into Influx DB, but I did manage to get it working… eventually. I then use Grafana to generate graphs from the data stored in the Influx DB.
@aaron33: To add a few details to your question - the voltage chart is what the AC200L is measuring (and what the app would display). I believe this is the voltage difference between the PV- and PV+ wires in the DC input port of the AC200L In my specific situation (and I see @rgb’s is a little different), the shade from a tree nearby starts to cover up just a few panels (which are wired in series with panels that are still in the sun. Normally, I would expect the voltage to drop (since these panels come with bypass diodes installed) in this situation as the MPPT controller would decide that it would be more optimal to just use the panels that remain in the sun (and get the full current from them) instead of trying to use all panels in series (but pull a much lower current - essentially treating all panels like they are in the shade). Indeed, on some days the AC200L does do this correctly. In this example from August 31st, between 15:00 and 15:40 you can see the DC input power slowly drops as the shade creeps over each panel.
Moreover, you can see the DC input voltage drop during that time as the MPPT decides that it is more optimal to use those bypass diodes in the panels that are shaded (it doesn’t actually think about this - the MPPT is just looking for the max power point - but it has this effect). Once most panels are in the shade from the first rack, the voltage jumps back up as it is more optimal to use the second rack (which is still in full sun and is in parallel with the first rack). This seems complicated but the AC200L masters this with no problems (on most days), which I find impressive. Good work Bluetti!
However, (and this is a big however), sometimes the MPPT controller glitches out as I described above and I think it is getting stuck at a particular “max power point” value and not “reevaluating” what the new maximum power point should be (because more panels are in the shade now and it needs to check again to find the new max power point). I hope Bluetti can fix this as the MPPT controller on the AC200L is otherwise impressive. I should note that unplugging the PV array from the AC200L and plugging it back into the AC200L has fixed this “glitch” every time I have tried it (as described in the previous post). It is almost like the MPPT controller just gave up trying to find a new max power point until it gets manually reset. This seems like a DSP software bug that hopefully Bluetti can fix.
For some additional context (if this helps), here is what the PV array looks like (each panel produces about 100W of power in full sun and has about 25V open circuit, which puts this array well within the upper limit of the AC200L. The green links represent the panels being joined in series.
Hi @Craig1, We have reviewed the information and believe that the AC200L is functioning properly. The firmware upgrade has also made a positive impact. The drop in charging power may not only be caused by shading but also by reduced sunlight intensity. We recommend placing the solar panels in an area without any shading, as shadows not only affect the efficiency of the panels but can also damage them over time if exposed for long periods.
Additionally, to optimize the solar charging performance, we have pushed a new firmware DSP v2098.22 and ARM v2134.07 for you. Please upgrade the firmware and test if it improves the situation.
Please do not load any device when upgrading it.
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@BLUETTI_CARE: I checked last night and this morning, but it appears that no updates are available for my AC200L. I figured I probably have to wait 24 hours before updating, but it has been over 24 hours now and no updates are available.
I realize the shading situation isn’t the best right now. Long term, I would like to move the panels to a more optimal location (but this may not be possible for a while). So, for now, having the system pull as much as it can out of the shaded array (in the afternoon) will be beneficial. Thanks again for all your help with this. It is appreciated.
Serial number: AC200L2352000774061
Hi @Craig1, I am sorry we confused your SN number with another customer, that is the reason why you didn’t receive the new ARM and DSP. I have requested our engineer to push them again, please upgrade it later.
@BLUETTI_CARE: Thank you! I can see the update now. In order to monitor the AC200L in person after the update, I plan to delay this update until this weekend if that is OK.
I will report back after I get this installed.
Hi @Craig1, Thank you for getting back to us so quickly.
We are expecting your test result.
Please feel free to contact us if you need our help.
@BLUETTI_CARE: I installed the update last night. Given that this issue doesn’t come up every day, I will monitor the AC200L over the next week and report back after that. So far everything seems to be working, but it was a fairly cloudy day today, so it wasn’t a great test.
Thanks again for your time and help. Hopefully this update does the trick!
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