Good point. In the Netherlands there are tests being done with ultra fast batteries to take over the grid forming properties of 'large spinny things'. See: https://www.rwe.com/en/press/rwe-generation/2024-09-09-rwe-builds-ultra-fast-innovative-battery-storage-system-in-the-netherlands/
But saying that this power outage is caused by it is speculation at this point.
You're completely right. But I suppose @Renohren@lemmy.today was thinking of using the battery and solar panels for personal use in case the grid is down. Which in theory is possible but afaik it requires additional measures, just having the battery and solar panels installed doesn't mean your fridge will work without the grid.