There is a huge difference between prices hitting zero from time to time and the year-long average daytime price being zero. The latter is the thing that would bankrupt solar because that's when all of its generation occurs.
> with storage we’re also already seeing solar cover significant demand even after sunset.
Which is completely expected, because a moderate amount of storage can be used to smooth out time of day misalignment of demand with supply, and it makes sense to charge that with solar during the day whenever it's available. But the thing that's displacing is peaker plants rather than baseload.
> I don’t see how you get around having fewer hours per day to cover
It's not about being exactly 24 hours every day. It's about averaging 20+ hours every day instead of 12, and getting not just all 24 hours but also the higher price for all 24 hours on the days when the output of other generation methods is lower.
Expect that the price per kWh at any given time is inversely correlated with renewable output. What does that do to the profitability of renewables and what does it to do the profitability of something whose output is uncorrelated with renewable output?