So, when the sun is shining and the wind is blowing and the price is negative, savvy operators of battery storage, pumped hydro, etc. stock up on energy for later.
Then, when it's the middle of the night and the wind's not blowing, the price spikes, and those who stored energy ahead of time make a profit providing that energy when it's needed most.
Of course this is an abstraction, and I'm not an expert, but... are there utilities whose rate structure enables execution of this kind of arbitrage business model?
In the US, it is not uncommon for KWh prices to go down off peak at night.
Also in the US, utilities are regulated and the political impact of changing rate structures upward usually requires public hearings.
Finally utilities infrastructures are capital intensive and the investment models are based on long maturity bonds. Utilities operations are structured to the goals of investors who buy long maturity bonds. I.e. utilities are operated for low risk and stable cash flows that bond holders expect.
Basically, if you have the financial wherewithal to arbitrage utilities, there might more fruits on lower branches than what you describe.
I could be wrong of course and your billions of dollars could prove it.
Good luck.
The thing is though, this type of thing only really works if you have sufficient interconnection and are paying / recieving the market rate. You've got to have a pretty big system to get to interconnect at market rates. Home based tarrifs aren't going to cut it, because those are usually not refundable, at best your cost goes to zero, which probably doesn't justify your investment in batteries.
Now, if you were putting in batteries anyway, there may be peak shaving options in the controller to charge off peak and discharge on peak. May as well use some of the capacity you installed for redundancy on a regular basis to reduce your energy costs. Especially if you have other generation options. Maybe peak shave down to 60% capacity, if the remaining 40% still covers your use for several hours and you have a generator you can run when you hit 20%. Or if you have solar, peak shave down to whatever leaves you enough power to make it to the next sunny day (or just the next day if you're feeling lucky)
Basically you need to be able to cover the whole cost of installation in reasonable time by doing this arbitrage. And that possibly isn't simple.