The problem is what you'd expect - wind and solar are what are known as energy resources. They are not capacity resources. This is another way of saying what you already know - wind doesn't work in still air and solar doesn't work at night.

This presents a handful of challenges:

* Generators make a lot of their money when they run. WWS can displace thermal units, reduce their runtime/profitability and make them less economically viable. (Even though they currently provide essential services that cannot be replicated with wind or solar)

* Solar falling off at night (or during an eclipse) requires thermal generation to step in to make up the loss. Just as an example, the eclipse cost TX something like 14,000MW of generation over four hours. That's ~25% of grid load around the time. They had to turn on 14,000MW of generation over two hours, turn it back off over the next two, and then ramp it all back up as night fell. This is not easy to do.

* Wind and Solar are typically both distributed and remote. Power needs to be moved over long distances from many places. This adds both cost and complexity, but also the need for reactive support for voltage stability, etc.

I tend to support wind/solar, but you shouldn't lose sight of the fact it's very complex to get it right.

eia.gov statistics disagree.

https://www.eia.gov/energyexplained/us-energy-facts/