Well $7B now, and a fraction of that in 25-30 years to replace the aging panels and batteries. (I think 12-15 years is a common battery warranty for grid batteries with daily cycling, but why might fall even further in price in 15 years than solar).

The nuclear plant that is shutting down is already at the end of its original license, and the $7B of work would be for 20 years or less of nuclear.