For utilities the level ized cost per kWh is $0.04 for solar and 0.06 for natural gas. This includes all costs.

You are right that the grid current needs a mix of supply sourced (hydro, coal, natural gas ) and grid batteries to deal with loss of sun.

However it is cost effective to replace large chunks of fossil fuel power generation with solar. Texas buys more than any other state. China buys more than the rest of the world combined.

Getting to a high % of renewables is easy for many parts of the country, some parts. Harder…