In that case you'd also need to model how the cost changes if you combine solar with wind and other renewables. Wind and solar are to some extend complementary

In that case you'd also need to model how the cost changes if you combine solar with wind and other renewables. Wind and solar are to some extend complementary (there is statistically more wind when there is little sun and vice versa). You'd also need to account for distributing solar and wind across large geographic areas (i.e. the U.S. is so wide that there are a few hours difference between the sun setting on the east coast and on the west coast, somewhere wind is always blowing, etc.) There are probably studies that have done an analysis of this kind for the entire U.S. and calculated various scenarios. I know that these have been done for Germany and other European countries. A 100% renewable system usually comes out cheaper than including nuclear in the mix to any large extend (though Germany has no remaining old reactors which could get their lifetime enhanced relatively cheaply).