ESolar
| Company type | Private |
|---|---|
| Industry | Concentrating solar power technology |
| Founded | 2007 |
| Founder | Bill Gross |
| Defunct | 2016 |
| Headquarters | Burbank, California , United States |
Key people | John Van Scoter (President and CEO) |
| Products | Concentrating solar power plant solutions, heliostats, sun-tracking software |
Number of employees | 21 (at Sierra SunTower operations) |
eSolar was a privately owned enterprise focused on concentrating solar power (CSP) technologies. Established in 2007 by Idealab, an incubator based in Pasadena, eSolar engineered CSP plant solutions intended to offer an economical alternative to fossil fuels through the use of modular heliostat arrays combined with precise solar tracking mechanisms. The company operated out of Burbank, California, with John Van Scoter as President and CEO and Bill Gross as its founder. Available information suggests that eSolar discontinued its operations approximately in late 2016.
Heliostat design
eSolar’s heliostats were designed smaller than conventional industry models, allowing for mass manufacturing, prefabrication, and easier installation processes that lowered overall expenses. In 2013, the firm unveiled the SCS5 heliostat at the SolarPACES Conference, featuring a simplified frame that enhanced durability while reducing installed system costs by more than one-third.
Sun-tracking software
The company created sophisticated sun-tracking control software capable of calibrating and supervising each heliostat individually, resulting in superior pointing precision and improved thermal concentration effectiveness.
Power tower and electricity generation
The eSolar system employed heliostat arrays to concentrate sunlight onto a thermal receiver positioned atop a tower. In the direct-steam configuration, the focused solar energy produced steam to power turbines for electricity generation. Alternatively, a molten salt arrangement stored thermal energy for later use, providing greater operational versatility.
Module
At the core of eSolar's field design were scalable modules. The direct-steam model incorporated over 20,000 square meters of heliostats per module, divided into two subfields—north and south—that tracked the sun and directed energy to a tower-mounted receiver. This straightforward and uniform design eliminated the need for precision surveying or extensive ground disturbance. For the molten salt variant, a hexagonal solar field spanned more than 100,000 square meters of reflector surface.
A 46 MW eSolar power unit consisted of sixteen heliostat fields with corresponding towers, one steam turbine generator, and a steam condenser, typically covering around 100 hectares (250 acres). These 46 MW units were engineered to be scalable according to power requirements. When configured with molten salt storage, ten such modules could be combined to form a 100 MW solar power plant operating at a 50% capacity factor. Adjusting the number of modules enabled various plant sizes and capacity factors.
Sierra SunTower
In 2009, eSolar commissioned the 5 MW Sierra SunTower facility located in Lancaster, California, demonstrating its technology in practice. Connected to the Southern California Edison (SCE) grid, it was North America’s sole commercial CSP tower plant by early 2010. By mid-2018, the two main towers had been dismantled; however, the site remains intact.
The Sierra SunTower comprised two eSolar modules with a total of 24,000 heliostats arranged across four subfields focusing sunlight onto two tower receivers. The generated heat superheated feedwater used to operate a refurbished 1947 GE turbine generator producing electricity. The steam was then condensed back into water for reuse within the cycle.
Construction efforts provided over 300 temporary jobs while ongoing operations employed 21 full-time personnel. Recognized by the California Energy Commission as a renewable energy source, Sierra SunTower sold electricity under a Power Purchase Agreement (PPA) with SCE, supplying clean energy sufficient for approximately 4,000 homes.
The plant’s 5 MW capacity helped reduce emissions by about 7,000 tons annually—comparable to planting over 5,200 acres of trees or removing more than 1,300 vehicles from circulation.
Nevertheless, Sierra SunTower stopped commercial production in 2015 due to elevated operating expenses except during periods of intense sunlight. This underscored practical challenges and variability inherent in concentrated solar power systems.
Performance Data from US Treasury Department - Performance Report and Certification Form
Between August 1, 2010, and July 31, 2011, the eSolar Sierra SunTower produced 539 MWh of electricity, which amounted to just 12.6% of the originally forecasted 4,270 MWh. This substantial shortfall underscores the difficulties encountered in the early deployment of the company's concentrating solar power technology.
Production
| Year | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Total |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2010 | 1 | 13 | 31 | 47 | 66 | 75 | 73 | 65 | 53 | 24 | 20 | 8 | 476 |
| 2011 | 0 | 12 | 17 | 27 | 34 | 43 | 37 | 38 | 26 | 21 | 7 | 7 | 270 |
| 2012 | 2 | 23 | 57 | 82 | 113 | 122 | 105 | 83 | 78 | 61 | 31 | 23 | 780 |
| 2013 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 94 | 94 |
| Aggregate Total | 1,620 | ||||||||||||
Molten Salt-Based Solar Facility
Beginning in 2010, eSolar collaborated with Babcock & Wilcox Power Generation Group to create a modular concentrating solar power plant design utilizing molten salt technology, aiming for scalable capacities between 50 and 200 MW. Funded by the U.S. Department of Energy, this concept employs hexagonally arranged heliostat arrays that focus sunlight onto salt-in-tube thermal receivers situated atop central towers. The system heats cold molten salt from approximately 285 °C to about 565 °C, storing it centrally for subsequent electricity production. This design builds upon lessons from eSolar’s Sierra SunTower project and Babcock & Wilcox's water-based receiver expertise, as well as experiences from the Solar Two initiative, with the goal of improving operational adaptability and dependability for utility-scale solar power generation.
NRG
In February 2009, NRG Energy, Inc. entered into a partnership with eSolar to develop solar power facilities totaling up to 500 MW across California and the Southwestern United States. NRG contributed around $10 million in equity and secured development rights for three projects along with a portfolio of power purchase agreements (PPAs) to build, own, and operate up to eleven modular solar units based on eSolar’s concentrating solar power (CSP) technology. These installations were designed to deliver renewable energy under contracts with regional utilities seeking competitively priced, carbon-free electricity.
Penglai Electric
eSolar formed a partnership with Penglai Electric, a Chinese manufacturer of electrical power equipment, in January 2010 to construct solar thermal plants amounting to a capacity of up to 2,000 MW in China by the year 2021. At that time, this represented China’s largest concentrated solar power initiative with potential investments exceeding $5 billion. According to the master licensing agreement, Penglai was set to deploy eSolar’s technology beginning with a planned 92 MW facility in 2010. These solar plants were intended to be integrated with biomass operations to achieve an annual reduction of approximately fifteen million tons of carbon emissions. However, this collaboration appears to have since been discontinued.
Ferrostaal
In February of the same year, Ferrostaal, an international developer specializing in power and industrial plants, teamed up with eSolar to deliver turnkey solar projects in Spain, the United Arab Emirates, and South Africa. eSolar provided its solar field and receiver technologies while Ferrostaal supplied the power block equipment, served as the general contractor, and handled project financing.
General Electric
In August 2011, General Electric (GE) committed up to $40 million in a strategic investment in eSolar, enhancing their collaboration and facilitating the company's growth initiatives.
Aalborg CSP A/S
In December 2014, eSolar finalized a commercial agreement with Aalborg CSP to deliver a solar collector system (SCS) for the expansion of Sundrop Farms in Port Augusta. This development increased greenhouse capacity by 20 hectares and supported a decade-long tomato supply contract with Coles.
Recognition and awards
In August 2009, California Governor Arnold Schwarzenegger commended eSolar's Sierra SunTower for its role in promoting affordable, carbon-free energy solutions.
By December 2009, eSolar earned the title of 2010 Technology Pioneer from the World Economic Forum, acknowledging its innovative contributions and dedication to clean energy alternatives. Founder Bill Gross was featured in an interview with the World Economic Forum, emphasizing the company's visionary leadership.
During the same month, Power Engineering magazine honored Sierra SunTower as "Best Renewable Project" for its outstanding impact on global power generation.
In February 2010, Renewable Energy World recognized Sierra SunTower as "Renewable Project of the Year," highlighting eSolar's success in bringing solar thermal technology to commercial viability.
Additionally, eSolar was included in MIT Technology Review's 2010 TR50 list, identifying it as one of the world's most inventive companies alongside notable firms such as Google, Apple, and IBM.
In March 2010, The Wall Street Journal placed eSolar among the Top 10 venture-backed cleantech enterprises, citing its robust funding, experienced management team, and solid investor backing as significant competitive strengths within the clean technology sector.
Investors
eSolar has attracted over $182 million in funding from prominent investors including Google.org, Oak Investment Partners, NRG Energy, ACME Group, Idealab, and Quercus Trust.
Management
- President & CEO – John Van Scoter
- Founder – Bill Gross