A coal power plant costs $2M - $5M per megawatt just in capital costs. A solar plant costs $1M per MW. Given a coal capacity factor of 0.9 and a solar of 0.

A coal power plant costs $2M - $5M per megawatt just in capital costs. A solar plant costs $1M per MW. Given a coal capacity factor of 0.9 and a solar of 0.3, they're roughly equivalent. A coal power plant is similar to a nuclear plant -- they heat water to turn a turbine to generate water. There's no way a nuclear plant would ever be cheaper than a coal plant to build, and it would have to be to be competitive with solar in cost.