We can analyze this issue with historical weather data, and it turns out it's tractable. Using solar + wind + batteries + non-fossil fuel turbines enables 365/24/7 "synthetic baseload", 100% renewable.

See https://model.energy/ for a web site that will solve this optimization problem for you in various places.

> Winds can be low for extended periods.

So can sun, but that's why we build both where that's unusual. We've got plenty of stats and data gathering on where it's reliably sunny/windy enough.

> Winds can be low for extended periods.

I'm curious how true this is anymore. It sure feels like as the globe heats up we're getting windier and windier.