Concrete Services Goes Solar

May 2011

The Kaiser Hospital campus in Vallejo received a major facelift with almost 4,400 solar modules installed in three locations on the site. This site offered its own set of challenges from drilling through an existing post-tensioned (PT) 4-story parking garage deck (occupied no less) to challenges with underground utilities, ground water and soil conditions for the drilled concrete piers in the parking lot.

The ground mounted system involved concrete piers 8’-12’ deep and 2.5’-3’ in diameter to hold the steel structure above the parking lot, directly across from the main entrance to the hospital.

To erect the steel structure on top of a parking garage 120 holes needed to be drilled through the existing PT deck in the parking structure so the base plates could be through bolted on. The locations for these holes were painstakingly selected to avoid reinforcing and PT cable using Ferro Scanning and Ground Penetrating Radar (GPR). Each base plate was unique with a different layout. The steel structure provided the framework for the solar array to sit on above the cars.

The total size of the system just barely exceeds 1 megawatt.