In my case, the behaviour seems much more extreme than a normal rescan. As you can see in the attached video, the MPPT power drops very close to 0W even though solar conditions are stable.
This does not look like a typical short rescan that lasts only a few seconds.
Also, this behaviour happens more often, not just at long intervals like every 30 minutes.
Could this indicate a possible issue in the MPPT firmware or some specific interaction in my setup (ESS + Fronius + battery)?
I am happy to provide more data or run additional tests if needed.
I think we already have something to work with. You are right. You can see the rescan squigles on this chart, plus that one time where it completely drops out.
The Multi is lowering the charge voltage. Let me look into this some more. This is not the first time I’ve seen something like this, but it is the first time I’ve seen it where there is no PV-inverters involved.
Your site did this again today around 10:33AM. Data logging says the reason for the outage is no input power. Check your PV wiring, it might be as simple as a loose connection.
I would like to share a final update regarding the issue.
After a detailed inspection, I decided to redo the entire DC side to eliminate any potential weak points.
The following changes were made:
all MC4 connectors were replaced with original Stäubli EVO2 and properly crimped
MC4 Y connectors were replaced with original EVO2 splitters
fuse holders were upgraded to a higher quality Eaton unit
fuses were replaced with correct gPV 32A (Mersen)
After these changes, the system is now stable with no more drops or fluctuations under load.
I believe the root cause was related to connection quality on the DC side rather than the system itself.
Also, many thanks to Izak Burger (iburger) for the analysis and guidance, which helped me focus on the DC side and identify the issue. I really appreciate it.
Currently, the system occasionally performs an MPPT rescan after a few minutes. During this, the power briefly drops, but it no longer falls to zero. Within a few seconds (around 10 seconds), it always returns to maximum power without any instability.
I would appreciate it if you could continue monitoring or reviewing setups like this, as I believe this configuration could be useful for further improvements or optimizations in the future.
Thank you @Oldrich77 for confirming. On my end the issue wasn’t dead, I had discussed it with one of the solar charger firmware guys, who was just as puzzled as I was. I’m glad that you managed to resolve it in the mean time. Always good when it turns out to be something simple.