Nuclear plants often operate at 90%+ capacity factors, while solar can range from 10-25% depending on location. So you might need 4-9 times more solar capacity to match total energy output. So depending on the region, you might need 4-9 gigawatts of solar capacity with a higher amount of battery storage to match 1 GW nuclear output. This is because you need to account for winter vs summer, for bad weather etc. Maybe it will take a lot more space and cost more to build than restarting a nuclear plant for 1.6 billion.