Also, I agree their usage is really high. They should not be running a $14000 electric bill at an office that only operates 5 days a week. Unless, they are running multiple offices with that and several servers or something. I don't know.

With regard to the 13.5% figure, I used it because I knew that for a 13.5% level of efficiency, you could buy a relatively cheap panel that'll last 25 years ($360/panel), whereas the newer, more efficient panels that get efficiencies between 20%-30% are rather expensive to the point that they might not be the best choice economically. Their prices are still coming down because newer, more highly efficient solar panels* use very recent technology that is becoming cheaper to produce now that they're out of development, but aren't quite as cost-effective as other solar panels yet.