Six months of balcony solar, and the utility hasn't said a peep

Ran basially the same experiment two summers ago with a single 400W panel on the garage roof feeding into an outdoor socket on its own circuit. I logged my hourly usage from the utility website for a couple months before and after, and the pattern was obvious on paper but tiny in dollars, maybe a handful of kWh on a good day, mostly eaten up by the fridge and the chest freezer running midday anyway.

The utility never said a word either. What actually mattered for my bill was the tiered rate structure, so the small daytime offset kept me under the higher tier in summer, wich is where the real savings came from. Worth checking wheather your plan has tiers or time-of-use pricing because that changes which hours your panels are worth the most. One thing I noticed that you might see too: on partly cloudy days the smart meter data gets choppy because the output swings around and your baseline usage starts blending in. I stopped trying to attribute every dip and just compared whole months instead. Much saner.

Only real annoyance for me was the inverter's wifi dropping out whenever the router rebooted, so my monitoring app had big gaps til I set it up on a static address. Otherwise it just quietly did its thing for two years until I moved.

My expirience went the other direction on the utility noticing part. I put a 600w plug-in kit on my apartment balcony, two panels and a micro inverter, same idea as yours, and for about four months it was totally quiet. Then a letter showed up asking me to declare any generation equipment on the account. I called the number on it, told the guy exactly what I had, and he said as long as it stays under their small threshold and I never push power back onto the grid, they just make a note and move on. Filled out half a page, done. So they do have ways of spotting it, probably from the usage shape on the meter, they just don't bother until it crosses some line. Worth calling them yourself if you'd rather pick the moment. My bill difference is small too, maybe 20 to 30 kWh a month in summer, but I like watching the curve dip at noon.

The utilities mostly don't care because thier monitoring gear is ussually pretty ancient. They are looking for big industrial feed problems, not some guy running a couple panels off a balcony. They are primarily concerned with net metering agreements and whether the local grid is taking a sudden hit, not your modest power reduction.

When I tried something similar years back, I noticed their automated system only checks the aggregate data a few times a day. Small, intermittent spikes and dips like you are prolly seeing get averaged out or ignored unless you are actively selling back a significant portion of your output. My experience suggests if you are just offsetting your consumption, you are fine.