There is huge demand for electrical power, but there is only huge desire for clean electrical power. I'm sure Bitcoin miners want to use clean power, but if it means they have tighter margins as a result, then non-clean will be what they stick with. (Bitcoin used only as placeholder here).
You're making the zero sum economic fallacy. More demand for solar panels finances more panels growing, increasing economies of scale reducing panel costs, and also, quite literally growing the total capacity of panels available in the world.
Solar panels already have huge economies of scales and lots of research investment; as a matter of fact, their price has been coming down incredibly fast thanks to those. There is no reason why adding bitcoin there will increase that speed.