since when is roof space valuable

Since whenever you had start to paying people to install stuff on their roofs ;)

but have you never heard about wind?!

Literally the next sentence: "when there's no wind or there's a drought". Yes there's probably gonna be some overlap of stuff like bad weather causing solar dropout while bringing more wind, but you're also just as likely to get a windless night. Meanwhile

you have double or triple the money just for building storage

Well it did cost $120M to build a 150 MW battery in Australia. Looking at some prices, it would take roughly $150M to make a solar array of that same power capacity.

So theoretically if you wanted to match a modern 1600MW reactor, you'd need 3200MW of solar to cover both day and night, plus 1600MW of storage. That would roughly take $1200M for the battery and $3200M for the panels, a total of $4,4B. Reactor prices for this power would range between $3-8B, so it seems to be on par with cost.

The problem is we're physically unable to construct enough lithium batteries for these projects all around the globe.