One of the largest distributed commercial solar retrofit projects in California required creative planning, design and logistics. In April, Sacramento-based HMH Builders completed the first of 15 1 MW photovoltaic additions to health provider Kaiser Permanente buildings up and down the state as part of an Engineering, Procurement and Construction agreement with San Francisco-based solar developer Recurrent Energy.
Because the first application was on the 400,000-sq-ft rooftop of a regional distribution center in windy Livermore where gusts can reach 115 mph, HMH switched from a planned ballasted design that used weights to anchor photovoltaic trays to a connected system. Steel frames were attached directly to the roof support without interrupting operations in the working facility. HMH removed 1-ft by 2-ft by 10-in. sections of Cellcrete roofing to attach 670 individually-mitered block-and-post assemblies. “Each block had to be individually cut to match the compound slope of the roof so the frame fit flush to the roof and maintained a 20% tilt for optimum solar radiation collection performance,” said HMH Solar Project Manager Kevin Kaaneh.