Parallel LV6548 inverters - Problems with SolarAssistant

[Jazzmonger]

SA worked flawlessly with my LV6048 single inverter, however I'm having nothing but problems with my new dual LV6548s.

The invertera are working great and both are set up as dual phase (180). I'm running my entire shop and a 25,000 btu air conditioner all day on just solar. All indications on front panels of the inverters work as expected and show all the correct data. WatchPower (what an absolute pile of garbage and poor excuse for software app) is at least reflecting the correct status and measurement values of each inverter Via Wifi.

I have 2 USB cables going from each inverter to the Pi, however only one cable is detected. I've tried swapping USB cables but it alwas defaults to connecting to the same inverter and showing the second via "parallel" connection:








Now, this should be fine, but the second inverter is missing data on all PV inputs:





WatchPower reports each units stats correctly.

Another strange thing is the power usage stats are totally w ring, possibly because of the missing PV data.
Anyone have any ideas? My usb cables are known good quantities, I've rebooted the Pi, swapped cables, reset inverters, etc.

update: Pierre at SA says mppt2 pv data is not available over the parallel connection. Interesting. I'll also replace both usb cables when I get Hm and swap the pv inputs from 2 to pv1. It was just easier to plug into the pv connection on the left which happens to be pv2. It figures I chose a config that just doesn't work. Note this is not a limitation of SA,it's due to a limitation of the info over the parallel connection of the inverters.

Jeff

 

[Jazzmonger]

Resolved. old Amcrest camera usb cables don't carry data... only power.

 

[timselectric]

This possess a question. If you have PV connected to #1 and #2, does SA only see half of the production?

 

[Jazzmonger]

Good question. It may depend if you have both inverters direct connected. if it's via parallel connection, apparently not.

I'm still having trouble getting the 3rd inverter to be recognized by the direct connection. Sometimes it works, but mostly it doesn't. My Pi4 wouldn't work at all so Im now using my Pi3b+. I also moved my PV wires from my 2 panel arrays to #1 so I'm getting the correct values now via the parallel cables so not sure it matters in my case.

I experienced Extremely strange behavior with the Pi4 and SA. It was getting power from the usb cables on both the lv6548s and SA wouldn't recognize anything at all when all 3 inverters were plugged in, and the pi would stay on when turning off the power supply. The pi3 seems to handle it ok. Perhaps modifying the usb cables to disconnect the + power wires would resolve it, I'm just not that ambitious... yet... Besides, I'm going to try to use the Pi4 for a touch screen interface to SA in my solar shed.

The inverter screen display has changed in that the lv6048 only shows one ac output. But the values are all correct and match the inverter displays (with a slight delay).

 

[Quattrohead]

That is a known issue with the Pi4, you need a non power USB cable.

 

[Jazzmonger]

I think this calls for more investigation.... there's no such thing as a "data only" or "non power" usb cable unless you make one.

The Pi USB issue involves the USB "C" port that's used for powering the Pi, presumably not the USB A & B ports used for peripherals. The USB C power port on the Pi4 design was wired (incorrectly) inside the Pi with only one resistor, not 2 as required by the USB specification so some C cables simply won't power the Pi. That's not the issue I'm seeing.

Also, I've heard of power only usb cables (I have some from Amcrest), but not data only. In fact,the USB spec specifically calls out the requirement to have +5v on pin 1 of all usb connectors. There is no standard USB cable that I know of that doesn't conform to this spec unless it's been modified.

here's a hack that might work, although I'm more inclined to open the cable and cut the red wire. Tape isn't a very good choice.

Put tape on the 5V pin - Why and how

First of all this whole tutorial isn't a mandatory mod - you just need it if you run into issues (weird things are happening and you've already ruled out the more common suspects) or if the always running fan and illuminated display (even when the printer is turned off) disturbes you. I'm...

community.octoprint.org

I'll investigate this further with Pierre at Solar Assistant and get his thoughts.

 

[Skypower]

I’m running MMP LV6548 twins in split phase. The two cables are USB to micro USB and works fine. I do unplug the USB’s before I power down the two inverters. If I don’t, one display stays on with a fault code.