A coal plant costs about $ 2 billion, and there are 241 of them in the US. So that's $481 billion. They provide 23% of US generation capacity. So if we assume a similar cost, that's $2.1 trillion for the total US generating capacity. But you say solar can do it for $800 billion. So now you have to explain why, if solar is really that cheap, the power companies like to throw away trillions of dollars on more expensive tech.