Solar power doesn't pollute and I would argue that all other forms of power that do pollute aren't taxed nearly enough for it, with coal being the most obvious example.
Coal power sends an insane amount of carbon into the atmosphere. If we properly carbon-taxed coal, it would go out of business tomorrow. And that doesn't even get into the environmental destruction that comes from strip mining.
Strip mining is when coal companies buy a whole fucking mountain and then destroy it piece by piece to remove the coal. How the fuck is that not good for the environment and our society after the coal is gone?
So, solar power really is a lot of cheaper than coal when you consider all the negative externalities that it brings.