Just yday learned something about microwaves (kitchen appliance). First produced by Raythreon in 1947 were big and expensive ($68,000 in 2023 dollars). By 1986, roughly 25% of households in the U.S. owned a microwave oven, up from only about 1% in 1971. Same goes with solar - it's so cheap now everybody can get small installation. So it's breaktroughs, then incremental improvements in efficiency and production cost. Commercial availability allows scaling and further fall in production cost. It takes time...