You should be wondering about the combination of solar + wind energy + short term storage + long term storage.
Usually, but not always. You can have many days or weeks, e.g. in mid-winter of overcast weather and very little wind. This is a real problem for renewable energy sources, they're not comprehensively viable unless supplemented by alternatives like gas peakers or perhaps nuclear.
This model posits 97% carbon free generation in Australia with 5 hours of storage using actual real world weather data:
https://reneweconomy.com.au/a-near-100-per-cent-renewables-g...
>You can have many days or weeks
Maybe cite actual data.
>alternatives like gas peakers or perhaps nuclear.
Nuclear isnt a peaker. Or rather, it can theoretically be used as a peaker but burning literal $100 notes may be more cost effective in the long run than using it as a peaker.
Batteries and pumped storage are cost effective peakers. I find it's better when modeling renewable energy generation scenarios to try not to pretend they dont exist.
You're confusing pumped storage with river dams. The geography for pumped storage is abundant, river dams not so much.
>Battery storage is entirely speculative so far.
In 2012 maybe. These days grid level battery plants are deployed routinely.
>Whilst nuclear is a proven baseload source
At 5x the cost per kwh, according to lazard.
Baseload also means "requires peakers". That means gas or...batteries.
When french nuclear plants go down for maintenance the country chews through ungodly amounts of gas. Some of their plants have capacity factors of like ~80% - not much better than high performing wind farms.