Soitec 1MW Concentrated Photovoltaic (CPV) Demonstration Project for On-Site Distributed Power Generation
Patrick Rowe | Soitec Solar
Objectives of the Demonstration
Soitec constructed a (1) MWAC power plant (“Project”) at the U.S. Army’s installation at Fort Irwin, California, to demonstrate the Concentrix® (CX) concentrating photovoltaic (CPV) technology and address the Environmental Security Technology Certification Program’s (ESTCP’s) objective of cost effective on-site distributed energy generation. The Project employed 40 Soitec CX-S530 CPV systems and included third party performance validation by the National Renewable Energy Laboratory (NREL) and solar forecasting development expertise by the University of California at San Diego (UCSD). The data collection and observation period ran from 28 July 2015 to 28 July 2017 (24 months).
The Project’s objectives were to demonstrate to the Department of Defense (DoD) the reliability and cost-effectiveness of the CPV technology in a harsh desert climate with high Direct Normal Irradiance (DNI, which means direct sunlight) a majority of the year. Additionally, the solar forecasting system, a component of the Project, was intended to produce a direct, measurable benefit to the DoD by providing cost-effective ways to manage and distribute on-site solar generation, resulting in increased energy quality and security.
CPV technology converts sunlight into electricity with state-of-the-art Fresnel silicone on glass lenses concentrating sunlight onto high performance multi-junction solar cells. The modules are mounted on dual axis trackers that follow the sun’s trajectory throughout the day. Fresnel lenses concentrate the sun by a factor of approximately 500 onto a small solar cell, thereby reducing the size and amount of costly cell material required.
Soitec has found most end-user concerns with CPV revolved around the financeability of the CPV technology. These concerns are categorized as:
- Dual-axis drive. The drive unit, though composed of a standard housing, slewing rings, worm gearing, reduction gearboxes and alternating current (AC) motors, was a source of end-user concern. Major worries were how the drive would handle the large tracker loads (especially during wind or seismic events), if the drive’s precision would support the exact pointing requirements of the CPV tracker (especially over time as the gear teeth experienced wear), and the general lifecycle of the drive.
- Soitec’s Long-Term Viability. End users, developers and investors were concerned about what would happen if Soitec went bankrupt or abandoned its solar business.
- Equipment and Implementation Costs. Equipment costs for this Project were over $1.20/watt. During the same time period, conventional PV module efficiency rose moderately and prices fell precipitously. Support technologies, such as 3rd party single-axis trackers and inverters have seen a shakeout in the industry, with quality rising and prices falling.
- Operations and Maintenance (O&M) Costs. End-users were concerned at the lack of real O&M cost data, realizing that the CPV technology was unproven and could require intensive preventive and reactive maintenance over the life of the plant.
- Lack of Commercialization of CPV System Components. At the time of construction of the DoD Fort Irwin project, the Soitec Bill of Materials were a combination of standard commercial off-the-shelf items, custom-built parts, or newly commercialized parts.
In 2015, Soitec announced its exit of the solar business and began the divestiture process. In late 2016, Soitec sold its CPV technology to Saint-Augustin Canada Electric Inc. (STACE), a worldclass supplier of large electrical equipment in the power generation industry. With this acquisition, STACE became the technological leader of the CPV industry and stated it would continue to improve the technology and maintain the collaboration with the recognized Fraunhofer Institute for Solar Energy Systems ISE, based in Freiburg, Germany.