Topaz Solar Farm, California, US

At its full operational capacity, the plant produces enough electricity to power more than 181,000 homes.

According to BHE Renewables’ estimates, this is sufficient to remove about 407,000 metric tonnes of carbon dioxide per year. This is equal to removing 77,000 cars from the road.

Topaz Solar Farm entailed an investment of around $2.5bn. It created 400 jobs during the construction phase.

Site and location details

Covering an area of around 4,700 acres, the Topaz Solar Farm is situated in unincorporated eastern San Luis Obispo County, California, near the community of California Valley. The site, which primarily includes previously disturbed agricultural land, is around 6 miles from the Carrizo Plain National Monument.

Santa Margarita and Highway 101 lie nearly 40 miles to the west, while Interstate 5 is approximately 50 miles to the east.

The project can be accessed through the California State Highway 58 and Bitterwater Road.

The location in California was selected due to its proximity to existing electric transmission lines and environmental factors.

Project details

The Topaz Solar Farm consists of around nine million thin-film cadmium telluride ground-mounted PV solar modules across an area of 9.5 square miles (24.6km²) as well as other ancillary electrical production and transmission infrastructure.

Each solar photovoltaic module has a dimension of 4ft by 2ft and weighs 27.5 pounds.

The modules are mounted together on panels supported by steel columns.

These advanced thin-film PV modules are capable of generating electricity without emissions, waste or water use.

The modules were installed within approximately 437 arrays.

The project includes an electrical collection system to convert the power generated from Direct Current (DC) to Alternating Current (AC). Subsequently, this power is delivered to the substation which collects and converts it from 34.5kV to 230kV.

A new on-site Pacific Gas and Electric Company (PG&E) switching station then delivers the electricity PG&E’s existing Morro Bay to Midway 230-kV transmission line.

Other project infrastructure includes associated electrical equipment, overhead collector lines, monitoring and maintenance facility, Solar Energy Learning Center, up to 22 miles of on-site access roads, leach field and septic systems adjacent to the monitoring and maintenance facility among others.

Contractors and agreements

Aspen Environmental Group won the contract to manage the preparation of Environmental Impact Report (EIR) for the Topaz Solar Farm. The company also supported a wildlife corridor study, a fiscal impact study, SB 610 water assessment and construction traffic assessment.

Environmental Management and Planning Solutions Inc. (EMPSi) prepared a Draft and Final EIS for the solar farm in 11 months.

First Solar manufactured the thin-film photovoltaic modules for the Topaz Solar Farm. The company was also the engineering, procurement and construction (EPC) contractor of the solar project.

The contracts of civil and transportation engineering, mechanical engineering, and surveying or GIS solutions for Topaz were secured by Wallace Group.

TRC secured the EPC contract of EPC for the Topaz Solar Farm Collection System. As solar panels are located on both the north and south side of State Highway 58, a crossing was developed to connect the collection system and energize the panels. Under a contract from First Solar, TRC installed steel encasement pipes under the highway to house conduits for the collection system power conductors and fibre optic cables.

Under a 25-year power purchase agreement, the power generated by the solar farm is sold to California-based Pacific Gas and Electric Company (PG&E).