Maxwell and Soitec Partner to Demonstrate Benefits of Integrating Energy Storage with CPV

June 11, 2013 by Jeff Shepard

Maxwell Technologies, Inc. and Soitec will collaborate on a California Energy Commission-funded, two-phase program to demonstrate the cost and efficiency benefits of combining an energy storage system with Soitec's Concentrix™ concentrator photovoltaic (CPV) technology. Maxwell has been awarded a $1.39 million contract by the California Energy Commission's Research and Development program to fund design and integration of an ultracapacitor-based energy storage system with Soitec's CPV system located on the campus of University of California, San Diego—one of the nation's greenest universities— and a second commercial scale system at Soitec's solar power plant in Southern California.

The integrated systems will also take advantage of other technology advances, including solar forecasting and predictive energy control, to maximize the benefit of incorporating ultracapacitor energy storage. The project starts in June 2013 and will run through November 2015. Independent evaluation of the performance of the integrated systems will be performed by DNV KEMA under a sub-contract with Maxwell.

"This innovative energy storage system combining ultracapacitors and Soitec's CPV technology, which is already installed on campus, is a welcome addition to UCSD's existing microgrid and provides a unique diversification of our existing energy storage capacity," said Byron Washom, director of strategic initiatives, University of California, San Diego.

"Investing in solar energy research is vital to California reaching its goal of 33 percent renewable generation by 2020," said California Energy Commission Chair Robert B. Weisenmiller. "This innovative project combining energy storage with concentrated photovoltaic technology has the potential to increase the state's renewable energy portfolio, decrease greenhouse gas emissions, and create a more reliable electricity grid."

Soitec's new fifth-generation Concentrix CPV systems incorporate modules with a 30 percent market-leading module efficiency (or two to three times the efficiency of conventional PV technology). CPV technology converts sunlight directly into clean electricity via concentrator optics and high-efficiency solar cells, offering the best design for use in sunny regions as it delivers environmentally friendly, low-cost, reliable solar-generated electricity. Additionally, the CPV system's two-axis tracker allows a high and constant power production throughout daylight hours.

Ultracapacitors are energy storage devices that charge rapidly from any electrical energy source and discharge their stored energy on demand. In combination with a photovoltaic system, their function will be to act as a standby reservoir of electrical energy to mitigate the variability of solar energy generation.

This firming of the output of a utility-scale commercial CPV system is intended to reduce demand on the electric grid to fill in short-term solar valleys in order to maintain a facility's electricity output. In addition to reducing the variability of a solar power plant, integrated ultracapacitor-CPV systems will benefit public utility customers by reducing investment in utility generation capacity to meet transient peak power demand.

"We are pleased by this new project with Maxwell Technologies," commented Clark Crawford, vice president of U.S. sales and business development, Soitec Solar division. "Soitec's durable CPV systems are specifically designed to deliver higher efficiency and lower cost of electricity. By working together, we are confident that we can improve the integration of solar power plants into the grid and ultimately increase the penetration of solar in the electricity grid helping California to meet its 33 percent renewable portfolio standard (RPS) goals."

Unlike batteries, which produce and store energy by means of a chemical reaction, Maxwell's ultracapacitor products store energy in an electric field. This electrostatic energy storage mechanism enables ultracapacitors to charge and discharge in as little as fractions of a second, perform consistently over a broad temperature range (-40 to +65C), and operate reliably for up to one million or more charge/discharge cycles.

"Electric utility grid applications represent an exciting new frontier for Maxwell," said David Schramm, Maxwell's president and chief executive officer. "This program is providing an opportunity to demonstrate how ultracapacitor technology can be applied to provide more efficient and cost-effective solutions for a variety of short-term power requirements."