They'll only block it until they can be the ones to own the battery plants. There is a hell of a market incentive to be able to purchase literally free electricity ans resell it later.

180 GW is power.
If you're talking about energy I suppose you mean 180 GWh.

They introduced some kind of caps (don't remember the details) on negative pricing quite early on, from what I understand it would have been very lucrative in the last decade or two to get into grid-scale battery storage without those caps.

One thing I remember is Flensburg building, pretty much on a whim, a water storage tank with immersion heater, an investment that amortised within a month or two as they were literally getting paid to fuel their district heating.

There's got to be some rules as to what you can do with electricity you by at negative prices, e.g. not just put an immersion heater in the ocean, maybe some prioritisation as to who gets the energy first just as there is on the production side (fossils have to shut down and pay if they don't do that fast enough while renewables get to produce energy), but overall I don't see why there should be a limit on negative prices.

Good thing then that Bundeskartellamt and Bundesnetzagentur are looking more closely at this now

I don't get why it is relevant. Energy is cheap and abundant today almkst everywhere that isn't sanctioned or a warzone.

Only if Germany changes existing legislation on power taxation. And do check out for how much a TWh of grid scale storage goes for. Hydrogen is the only borderline cost effective solution at the scale required.

https://archive.md/MueQc