The lurking threat to solar power’s growth

I think their point is that installing cheaper solar power doesn't generate extra revenue, because existing solar generation already exceeds demand (driving prices negative). So they need batteries to shift generation, but solar plants alone can't cover those capital costs, because they aren't generating extra revenue.

They do acknowledge that investors see all this and new power storage is being built (I mean, it can be as cheap as a couple of dams and some turbines), but they cite studies saying going to all renewables requires excess capacity (65% in one of those papers) which makes it much more expensive in the end.

Though how much more expensive once some hydro storage is built, they don't say. Probably not at all once they can deploy cheaper solar. It's sort of like an engine or pump that needs to be primed, and the author is a little pessimistic on investors.

The hourly price differential is great motivation for storage systems as mentioned. What it doesn't do is play this out. When there are various methods of timeshifting available energy, the price variation will also narrow. This will require more cost efficient storage mechanisms. There's nothing much to say here other than both solar and storage tech, not only batteries, will need to advance together.

My mother was an accountant. And I've made a point to get in the know with the accountants at the places I've worked.

I know what an accountant thinks about the idea that maybe you could buy power at 2pm for $200/mwh. And then sell it SIX HOURS later for $400/mwh. Bonus when I guesstimate depreciation for a 1 mwh of batteries I get about $75/day. So not hard to see how you get double digit returns a day.

Assume batteries cost $150/kwh. So 1000 kwh worth costs $150,000. At 2% interest you can finance that for $2200/month or $73/day.

Pencils out.