Sierra Sun Tower is a 5 MW commercial concentrating solar power (CSP) plant built and operated by eSolar. The plant is located in Lancaster, California and is the only CSP tower facility operating in North America.

The Sierra SunTower facility is based on power tower CSP technology. The plant features an array of heliostats which reflect solar radiation to a tower-mounted thermal receiver. The concentrated solar energy boils water in the receiver to produce steam. The steam is piped to a steam turbine generator which converts the energy to electricity. The steam out of the turbine is condensed and pressurized back into the receiver.

eSolar unveiled the 5 MW Sierra Sun Tower plant, a commercial facility in Lancaster, California that demonstrates the company's technology. Sierra SunTower is interconnected to the Southern California Edison (SCE) grid and, as of spring 2010, is the only commercial CSP tower facility in North America.

The project site occupies approximately 8 hectares (20 acres) in an arid valley in the western corner of the Mojave Desert at 35° north latitude.

Sierra Sun Tower includes two eSolar modules. 24,000 heliostats, divided between four sub-fields, track the sun and focus its energy onto two tower-mounted receivers. The focused heat converts feedwater piped to the receivers into superheated steam that drives a reconditioned 1947 GE turbine generator to produce electricity. The steam passes through a steam condenser, reverts back to water through cooling, and the process repeats.

During the 12 months of construction, Sierra SunTower created over 300 temporary jobs. In operation, the site employs 21 permanent employees.

Concurrent with the plant’s official unveiling, California Governor Arnold Schwarzenegger praised the eSolar solution, “…proving that California’s energy and environmental leadership are advancing carbon-free, cost-effective energy that can be used around the world.”

Sierra Suntower has been certified by the California Energy Commission as a renewable energy facility. Power from the facility is sold under a Power Purchase Agreement (PPA) with SCE, providing clean, renewable energy for up to 4,000 homes.

The 5 MW output from Sierra SunTower reduces CO2 emissions by 7,000 tons per year, an amount equivalent to planting 5,265 acres of trees, removing 1,368 automobiles from the road, or saving 650,000 gallons of gasoline.

Sierra Sun Tower was designed to validate eSolar's technology at full scale, effectively eliminating scaleup risks. The solar thermal equipment operating at Sierra SunTower forms a blueprint from which future plants will be built.

Sierra Sun Tower Awards

In December 2009, editors of Power Engineering magazine selected Sierra SunTower as the winner of the “Best Renewable Project”. Each year, Power Engineering magazine recognizes the world's best energy projects. The award distinguishes Sierra as an exceptional power generation project toward meeting growing global demand.

In February 2010, Sierra SunTower won Renewable Energy World’s “Renewable Project of the Year” award. The award recognizes eSolar's achievements in the clean energy industry by naming Sierra SunTower an exceptional breakthrough in the commercialization of solar thermal technology.