Back in 2008, the total amount of installed solar capacity in the U.S. didn't even reach 1,000 megawatts .
Fast forward ten years, however, and that number had grown by more than 20-fold, with total U.S. solar capacity just shy of 20,000 megawatts.
The reason for this explosive growth is pretty simple. Solar panel efficiency kept improving while prices steadily declined, as more and more Americans discovered that they could substantially lower their energy bills by going solar.