Innovations in solar technology

Nancy Hartsoch tells Power & Energy why concentrator PV has the power to revolutionize our energy system.

Despite the fact that solar power has been around for several decades, it still hasn’t made a major impact as a renewable energy source. Is this changing?

Over the past two decades progress has been made in solar technology, moving it forward as a large-scale energy source. However, the historical low efficiency of solar panels combined with the relatively high cost of solar material has made it difficult for the economics to work on a large scale without incentives. Currently, the industry standard is crystalline silicon-based technology, which uses the semiconductor materials of the microchip industry to convert sunlight into electricity. Though proven and reliable, traditional PV technology suffers from the cost of systems compared with the amount of energy generated. As a result, solar technologies that reduce the amount of expensive PV material are quickly coming to market. Thin films have been a major step forward, bringing new milestones to the solar landscape. The latest advancement has been concentrator PV (CPV) technology, which uses optical concentrators to boost the output of small, highly efficient PV cells. All of these approaches have inherent advantages and disadvantages in terms of cost, performance and scalability; however, CPV has begun to prove its ability to achieve high conversion efficiencies, and thus drive down the cost of solar energy.

Historically, new technologies have taken as much as a decade for the innovation to reach a reasonable market presence. Will this be the case for CPV?

We believe that CPV will be able to move from initial test deployments, which took place over the past two years, into large scale deployment much faster than other technologies such as silicon PV and thin film technologies. There are two primary reasons for this. First, CPV has its roots in existing technologies. It is a photovoltaic technology, so implementation of CPV technology in the field is similar to traditional flat plate PV. It is also a concentrating technology, similar to reflective mirror-based concentrating solar plants, which have been producing utility scale energy at scale for many years. Also worth noting is that the ability to ramp manufacturing is much faster with CPV than other technologies. With our technology, the cost of capital for building a factory is just $0.15 per watt, and the time to stand up each additional 50 MW line is less than six months. At SolFocus, we have already ramped our manufacturing capability for CPV systems to a 50 MW run rate, just 18 months after deployment of our first large-scale test project.

Does concentrator PV provide a better solution than traditional PV or CSP for utility scale solar plants?

The right solar technology depends on where it is being deployed and the objectives of the project. Compared to other PV technologies, in regions where the direct solar resource is high, CPV brings a number of advantages not available from traditional PV technologies. CPV solutions have the highest conversion efficiency of any PV technology - at SolFocus, we are converting sunlight to electricity at over 25 percent efficiency with headroom to advance these levels rapidly. CPV systems also integrate the panels onto dual-axis trackers, which allow CPV technology to provide a broad energy production profile throughout the day, providing energy production late in the day to provide a better match to utility demand curves than other PV technologies. Also, since CPV systems don't suffer performance degradation at high temperatures as do other PV technologies, panel performance remains high. In combination, the high panel efficiency, broad energy curve and performance at temperature provide the highest energy yield in high sun regions.

CSP systems, sometimes called solar thermal solutions, also are targeted to the high solar resource regions. If there is a limited supply of water in the region (CSP consumes up to 1000 gallons of water per megawatt hour), environmental constraints around land use or protection of existing ecosystems, or the desire to deploy smaller plants from 1-50+ MW, then CPV provides significant advantages compared with CSP.

Nancy Hartsoch is Vice President of Marketing and Sales for SolFocus, with responsibility for global marketing and sales activities in North America and the Rest of World territories. Prior to joining SolFocus, she was CEO of Pacific Technology Group, which she co-founded in partnership with Taiwan-based Acer Labs Inc. (ALi). She has an MBA and a BA from San Jose State University.