BrightSource said the funding announcements close financing for the Ivanpah project, which was already set to receive up to $300 million in financing from power company NRG Energy.
The $168 million from Google is the company's largest investment in the clean energy sector to date, Google said in a statement.
"We're excited about Ivanpah because our investment will help deploy a compelling solar energy technology that provides reliable clean energy, with the potential to significantly reduce costs on future projects," the company said.
The Ivanpah project will consist of three related utility-scale solar thermal power plants located on federal land in the Mojave Desert in southeastern California.
The majority of solar power projects developed to date have been photovoltaic systems, in which sunlight is turned into electricity using semiconductor materials in panels.
But Brightsource will use thermal, or concentrated solar power stations where mirrors concentrate sunlight on a fixed point to heat a liquid that produces steam to power a turbine.
When construction is completed in 2013, the 392-megawatt project will provide enough power for more than 85,000 homes, the Energy Department said.