The 11 plus acres, located north of Taylor Street, was determined through independent studies to be the best location for the new Caltrans office complex facility. The project entailed construction of a District Office complex, and storage facility of approximately 30,000 square feet. In addition, there is an automotive shop and surface parking for approximately 815 vehicles. The new facility houses 956 employees.

One of the most prominent features of the new district office is Caltrans’ solar electric (photovoltaic) grand trellis. The trellis appears to reach out to drivers on Interstate 8, providing a powerful reminder that there are alternative solutions to the existing energy crisis.

Challenges

Caltrans was charged with providing the following project goals:

• Provide a safe and efficient office facility for the District’s employees
• Reduce the District’s operating expenses

Several studies were performed to determine the feasibility of these goals. Caltrans became interested in renewable energy as a means to provide efficient operations and reduce operating expenses.

Christopher Gerber of Carrier Johnson, the project architect, states that he thought of several materials to use for the trellis structure. His thoughts were, why pay millions of dollars for materials that did not produce anything. He realized utilizing solar photovoltaic modules to provide the shade would also be cost effective. The modules would pay for themselves and offset other material costs. This would be the only part of the project that would provide such a benefit.

Solution

Borrego Solar was charged with the task of designing and installing a solar electric system that would reduce electricity bills for the new district offices. In addition the system would be constructed on 70’ high tubular steel purlins forming a Grand Trellis.

Borrego Solar provided the mechanical and electrical installation of the photovoltaic array. Installation consisted of 336 Unisolar 64-watt solar modules and one 20 kW Xantrex inverter. The Unisolar modules use multi-junction amorphous silicon cells to produce direct current (DC) electricity. The DC electricity is converted to alternating current (AC) at the inverter. The inverter feeds the electrical loads onsite. Once all loads are satisfied, the electricity spins the meter backwards, accruing a credit from SDG&E.

The solar electric Grand Trellis serves a dual role. While the sun is shining, it both produces clean electricity and provides approximately 10,000 square feet of shade for Caltrans employees and visitors.

Financial Benefits

Caltrans took advantage of a $59,000 rebate from the California Energy Commission. Commercial entities investing in solar also qualify for state and federal tax credits and short-term accelerated depreciation.

Caltrans is helping to reduce the state’s energy traffic. California’s energy consumption, particularly during peak daytime hours, is increasing at an exorbitant rate. This solar electric system helps to alleviate stress on the grid during the most congested periods.

With the installation of their solar electric system, Caltrans is paving the road to California’s energy security and environmental sustainability.