I recently ran across this interesting graph on reddit:
Click to embiggen.
The title of the article in which the graph was housed (similar to mine above) was: “Solar Energy: This Is What A Disruptive Technology Looks Like.”
I think the graph is pretty clear — while the price of retail electricity, residential natural gas, and crude oil have all remained fairly constant in the past few decades (in inflation-adjusted terms), the price of solar has rolled down a long, big hill. And, the good news is, it’s still rolling.