Well that's what has me VERY concerned. I DO NOT want back feed EVER. I was under the impression by setting my tp6048 to not back feed I was 100% SAFE. After all of this crap luxpower or whoever is now telling us that EVERY hybrid inverter can back feed I'm VERY concerned so this thread going on in hopes of me understand if this can happen with my unit or not is the most important piece of info I hope at this time to get out of this forum !
I did quite a bit of reading on this with regards to Victron, as I had hoped to (eventually) integrate their inverters in my home, very much the same way it would be implemented on an RV.
In other countries (especially South Africa), the utilities strictly enforce anti-backfeed measures via smart meters that will sever the connection to the utility if backfeeding is detected. Apparently some of them are
extremely sensitive.
Victron says that a small amount of backfeeding can't be prevented--if inverters are powering a large load that suddenly switches off, for example, some power will leak out to the grid faster than the inverters can respond. They suggest using a positive grid setpoint (say, 50W grid draw) for their Energy Storage System, to help mitigate this issue.
I've read somewhere that SMA Sunny Islands are very good about never backfeeding
at all, if they're set up to never do so. Not sure how they manage to solve the above-referenced issue.
I gave up on the idea, since my utility insists I go through the Net Metering approval process if I wish to connect any inverter to their grid, period. I asked about my APC UPS, and never got a response.
edit - I don't think OP's issue had anything to do with the tiny "blips" I just described. More like some kind of logic error in the firmware causing measurable, sustained backfeeding.