China to Build Solar Mirror Farm Using Oakland Company’s Technology by Katie Fehrenbacher @FortuneMagazine September 27, 2016, 1:02 PM EDT E-mail Tweet Facebook Linkedin Share icons China is turning to alternative solar technologies to fill its insatiable appetite for energy from the sun. Solar company BrightSource Energy, based in Oakland, Calif., said this week that it has signed a deal to sell its solar farm technology to a Chinese project owned by a state-run energy company. The technology, the same used at a big solar farm outside of Las Vegas, uses thousands of mirrors to concentrate sunlight on a boiler filled with water that is perched on top of a tower. The process heats the boiler’s water to high temperatures to turn a steam turbine that then generates electricity. In comparison, more commonly-used solar panels that use semiconductor material convert sunlight directly into electricity. Typically called solar thermal or solar concentrating farms, the mirror-based technology was once seen as a major way that solar energy could compete with large coal plants. Solar thermal farms can be very large in size and produce hundreds of megawatts of energy. For more on how solar energy works watch our video. However, as the price of solar panels and natural gas has plummeted, many utilities in the U.S. and Europe have chosen to instead buy energy from large solar panel farms or natural gas plants. In recent years plans for solar thermal farms have become much less common. But in some regions, where land is abundant, and where large amounts of energy are needed, solar thermal farms are still being built. For example, a huge 580 megawatt solar thermal farm is under construction in the Moroccan desert that could power the equivalent of nearly 100,000 average American homes. Many solar thermal companies, in a bid to be more competitive with solar panels and natural gas, also started selling energy storage technology that enables power company customers to store solar energy during the day so that it can be used later at night. BrightSource Energy’s solar farms can use steam to heat up large tanks of molten salt, a particularly good medium for retaining heat. Get Data Sheet, Fortune’s technology newsletter. China has decided to aggressively build solar thermal farms along with a massive number of solar panel farms. The country plans to deploy 10 gigawatts of solar thermal farms by 2020. Another American company called SolarReserve is also building solar thermal plants in China. BrightSource Energy’s technology will be used in a 135 megawatt pilot project in the Qinghai province in northwest China that will be owned by a subsidiary of China’s State Power Investment Corporation. The farm, called the Huanghe Qinghai Delingha Solar Thermal Power Generation Project, is supposed to have multiple towers and storage. It will be built by a joint venture between BrightSource Energy and Chinese power company Shanghai Electric Group. BrightSource’s technology is the same one used to build the $2.2 billion solar thermal farm called Ivanpah, which was partly built by Bechtel and was funded by Google GOOG and a $1.6 billion loan from the Department of Energy. That plant, which sells power to PG&E and Southern California Edison, has faced accusations that it hasn’t been generating enough power, and has killed too many birds with its concentrated sun beams. Solar panels stand at the Ivanpah Solar Electric Generating System in the Mojave Desert near Primm, Nev. Photographer: Jacob Kepler/Bloomberg via Getty Images Other U.S. solar thermal plants have also faced problems. A solar thermal farm built in Gila Bend, Arizona, was fined for emissions violations. Abengoa, the Spanish company that built the Arizona solar thermal farm, is now restructuring and recently sold off its biofuel plants. Meanwhile, French power company Areva decide to ditch its solar thermal business, which it acquired by buying a startup called Ausra about two years ago. BrightSource, founded in 2004, was funded by Silicon Valley investors VantagePoint Capital Partners, DBL Investors, and Draper Fisher Jurvetson as well as Morgan Stanley, BP, Chevron, and Alstom. The company flirted with going public in 2011 but later cancelled its IPO plans.