I have a Apex300 with 2 B300 and 1 B300k batteries.
I have connected 2 solar panels in parallel to one of the MPPT port (I am reserving the other port for more panels later) and observed an unusual behavior.
The solar panel have Vmp of 43V and Imp of 12A, I have 2 in parallel. I would expect the current to be clipped at 20A but voltage to remain around 43V at max sun. But for some reason, the MPPT has set it to 20V and 20A. The voltage measurement is confirmed at my DC breaker which is close to the Bluetti.
I then covered one panel with a big towel, now the MPPT sets it to 41V 8A. Same thing with if I cover the other panel instead. I then uncovered both, and it is running at 40V 12A combined.
What would cause the MPPT to run 20A 20V instead of riding the voltage up and drawing less current?
I believe that I have found an issue with the Apex300 MPPT
I have 2 Longi 545w panels connected in parallel into one of the Apex300 MPPT. The Longi545w panel (data sheet here) has Vmp of 42V and Imp of 13A. One would expect that in good sun condition, the Apex300 would receive around 42A 20A around 800W, and be limited by the 20A max input at or just above the Vmp.
In actual testing, I found that the Bluetti Apex 300 MPPT would usually receive 600-700W (38V 18W) as expected but would sometimes get stuck at 20V, pulling up to 20A but can be less. This tends to happen when there is transient shading. This voltage is real and I can confirm current and voltage independently. If I disconnect the MPPT and measure Voc, it is around 45W, and a disconnect and reconnect always resets it to expected operating mode. However, it never tends to recover on its own.
I believe that the MPPT is getting stuck at a local maxima, which may happen if one panel is temporarily shaded and a by-pass diode is triggered, dropping that panel’s Vmp to a lower point. The MPPT then moves to that lower point, but because it is a local maxima, it never recovers when the shade is gone, until a manual disconnect and reconnect, forcing a rescan.
Can you bring this up with the engineering team on the MPPT behavior? Perhaps the algorithm needs revision and triggers a rescan under more conditions?
IoT v8026.1
ARM v2204.09
DSP v2174.09
BMS v1073.06
Note: This doesn’t always gets pegged down to 20V, at times, the operating voltage would drift down from 40V down to 35V, then 30V to 25V… upon a disconnect and reconnect, it would resume at near 40V at much higher power level.
Did you check under Advanced Settings “DC Input Source” On my unit it was set to “Others” rather than the PV setting. It was causing my panels to not operate at the correct volatge.
That is the issue!
I didn’t recall changing it, but the “DC Input Source” was set to “others” instead of PV. I set it to PV, disconnected and reconnected, seems to be working find now. Thanks!
You did not change it, It came that way, factory set to the “Others” position. That is the same way mine was shipped which seems a bit crazy as most people are going to want to hook up to solar rather than an external non bluetti battery.
