The investment in the California-based firm was made through Google.org, the company's non-profit philanthropic venture.
The BrightSource deal is the second such investment Google has made in solar power, after taking a stake in eSolar last month.
BrightSource is raising cash in the hope of constructing a series of huge solar power plants in California's Mojave Desert capable of supplying up to 900MW of electricity.
"Solar thermal energy generation is one of the key emerging industries addressing the changing global climate and we are excited about our current investments in solar thermal technology," Google investment strategy manager Chris Busselle and green energy strategy team member Kevin Chen said in a blog posting.
"We believe that by supporting researchers and entrepreneurs taking different, ambitious approaches and risks to generate clean energy, we can help to accelerate, progress and increase the collective economic value of these new clean energy industries."
The investments are part of Google's 'Renewable Energy Cheaper than Coal' initiative.
The company is assembling a team of researchers and engineers in the hope of creating a Gigawatt of energy for less than it costs to generate the same amount at a coal-burning power plant.
In addition to solar power, the project is also looking at geothermal and wind sources.
Google is looking to hire a head of renewable energy research to oversee all of the firm's renewable energy research and development programmes.
Google beams cash into solar power
By Shaun Nichols on May 16, 2008 7:30AM