California enjoys a reputation as one of the most environmentally responsible states in the nation. The passage of Senate Bill 2X (SB 2X) last April, which requires California public and private utilities to obtain 33% of their electricity from renewable resources by the year 2020, further cements the state’s role as a leader in the green movement. In an effort to expedite delivery of cleaner energy to its 5.1 million electrical customers, San Francisco-headquartered Pacific Gas & Electric (PG&E), one of the largest combination natural gas and electric utilities in the United States, recently marked the completion of several solar photovoltaic (PV) stations.
“Our Energy Alternatives Division engineered and built two ground-mount solar farms totaling 35MW as part of the first phase of PG&E’s multi-year 250MW solar initiative,” says Tim Jensen, project executive for San Jose, Calif.-based electrical contractor Cupertino Electric Inc. (CEI). “The farms are located at separate sites in western Fresno County approximately 12 miles apart.”
Situated on 100 acres, the 15MW Westside solar station features 66,240 fixed-tilt polycrystalline 275W and 280W solar modules while the 20MW Stroud location encompasses 123 acres and includes 88,000 fixed-tilt polycrystalline 280W solar modules. Both generation plants employ 500kW inverters and are interconnected to the electric grid — with the approval of California’s Independent System Operator (CAL-ISO) — at local PG&E distribution stations.
“Because PG&E is a utility, we are talking 35MW of AC output, which is roughly 20% less than DC output,” notes Jensen. “In addition, the farms are 1,000VDC, which is a voltage class that is not yet used on a regular basis in the United States.
According to Jensen, obstacles faced by Cupertino Electric included the scale of the projects as well as an extremely tight deadline.
“These are the two largest projects that we have served as an engineering, procurement and construction (EPC) contractor as far as solar goes, and we had just a six month time span in which to complete them,” he says.
To help finish the solar farm installations on time, Cupertino Electric assembled the project team at its San Jose office to streamline engineering and pre-construction processes before mobilizing on site and beginning actual construction.
Perhaps the biggest challenge to overcome, however, was the extreme weather. During peak construction in June, July, and August, temperatures regularly reached more than 100°F.
“We crunched the numbers and figured out that we used more than 12,000 gallons of drinking water during that time to keep our employees hydrated,” says Jensen. “We brought ice machines to the sites to chill the water and made sure we provided workers with plenty of shade. A dedicated team of safety and medical personnel helped protect our workers’ health.”
During the course of construction, Cupertino Electric employed 200 local workers, many of whom were provided by IBEW Local 1245. Furthermore, the contractor made a concerted effort to use diverse suppliers.
The Westside and Stroud solar station projects were finished on schedule on Sept. 1, 2011, and Sept. 26, 2011, respectively.