It is hard to tell how big this building is, but it is the headquarters of a prominent bank in San Angelo built long before modern green building and energy efficiency technologies. Their usage is very high, which is often the case with commercial buildings. The bank is very conscious about their energy footprint. Prior to installing solar, the HVAC system was upgraded, as is referenced in the article, and that also helped quite a bit.

The important thing to remember for all solar projects is that after the system is installed, 100% of whatever the actual offset is, is now powered by free fuel from the sun. It is about doing what you can with the space and budget you have, and something is always better than nothing!