We need to get out of the mindset that all power generators need to produce a steady amount of power 24/7. A flexible grid made of many power sources that can be ramped up and down can just as easily meet demand and may even be best since it is resilient when any one power source goes down for an extended period of time.
You can't just say that solar should be more expensive because it only works half the day. You could just as easily turn that argument around and say that nuclear and coal plants should be more expensive since they are only economical if run at a constant load and require long shutdowns every year for maintenance. There needs to be extra capacity on the grid to meet demand during nuclear/coal shutdowns, but no one states that nuclear and coal should be more expensive as a result.