September 2011 - I-Micronews

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S E P T E M B E R 2 0 1 1 I S S U E N ° 1 3 “Compared to the more established flat plate PV technology, HCPV likely has much more headroom for improving efficiency and cost,” says Milan Rosina, Yole Développement. throw at the work. Garboushian ticks off potential ways to gain a few percentage points improvement across almost all the various components in the systems - from better multijunction cell efficiency, to better pitch angles and more accurate facets in the Fresnel lenses, up through more accurate alignment in the balance of systems, which could together perhaps add up to as much as 50% improvement overall. Key to much of this improvement is the growth and increasing maturity of the supply chain. “While the solar supply chain continues to mature, there has been no shortage of innovation,” he says, noting that the optics and components are constantly improving. On the cell side, Garboushian notes that the best cells are already 5% to 10% better than those from some other suppliers, and spectral tuning for particular locations can add up to another 5% to 10% improvement in energy generation. But going beyond three junction cells won’t be an easy step for the optics and the rest of the system. Garboushian and Amonix have been making concentrating solar for some 20 years, and were among the pioneers of the big move from silicon to compound semiconductor triple junction cells for the boost in efficiency that did much to help create a viable HCPV market not so very long ago. The company’s early 7.8 MW-scale HCPV project with Guascor Foton in Spain in 2006-2008 used silicon cells, and depended on European government subsidies to be economic. Working with Emcore and Spectrolab to stabilize the process, prove the cell reliability, and redesign the rest of the system took a year, but it cut costs roughly in half and enabled output to jump from 25kW to 37kW. SolFocus permitting 30MW project, plans to double production capacity to 100MW SolFocus is stepping up to tens-of-megawatt projects as well, with a 30MW power supply agreement from San Diego Gas & Electric now in the permitting process, which may be ready to start installation later this year. Nancy Hartsoch, VP of marketing, says the company also plans to increase its production capacity from the current 50MW to 100MW this year, by adding a second $10 million robotic assembly cell at its assembly facilities in China. The San Jose, California, company has installed projects in a dozen countries, most so far relatively small, essentially to test the HCPV performance under various conditions at different sites around the world. Recent larger US installations include the 1MW Victor Valley College project, the 1MW Nichols Farm pistachio processing plant, and the ~0.5MW Coachilla water reclamation plant, the latter two particularly significant because they were put together by heavy weight project managers Bechtel and Johnson Controls, suggesting these big companies think it worthwhile to learn the HCPV business on these relatively small installations for its future potential. Another big step: the first performance warranty insurance for HCPV from Munich Re. Though the utility market will be the bigger one, Hartsoch also sees a strong market for HCPV in this type of distributed generation, for the educational, agricultural processing, and water treatment markets, all users that tend to have big electrical bills, extra land already, and renewable energy goals. Like most of the other companies in this young technology, SolFocus designed and originally made not only its own components, but even much of its custom production equipment, but as volume has increased, it has outsourced all production. The company’s founders decided from the beginning to focus on proven glass, aluminum and steel materials, and on designing for manufacturability as the best way to create a low cost product. Major parabolic dish glass supplier Flabeg makes the mirrors, using SolFocus-designed equipment to slump a square mirror. One of the big electronics assembly houses assembles the receiver units and optical cones, and an assembly company in China puts together the final systems, using a monster press to stamp out the backpan in one piece, and a three-robot cell designed to SolFocus specifications by a company from the automotive assembly industry. Hartsoch argues that the company’s unique optics design may add complexity, with its third non-imaging optic that focuses the light down through a prism to more evenly illuminate the cell, the unusually wide 1.6° acceptance angle allows more margin for some misalignment in assembly, installation and tracking. “You can lose a lot of energy for every 0.25° smaller acceptance angle,” she argues. The new generation systems just introduced swap out the cells for the next generation of more efficient ones, to boost panel efficiency to 29%, and redesign the modules for easier field assembly to reportedly reduce installation costs by cutting field installation time by half. The new modules add more panels per tracker, for fewer total trackers, and pre-assemble more panels into units, for fewer units per tracker to install, and no need for alignment in the field. The electronics are also now premounted on the tracker head, so no electronics assembly is required in the field. Hartsoch says that cut field assembly time in half. “And that’s with engineers,” she quips. “In the field with construction people it should be more than a 50% reduction in assembly time.” The relatively light dish units can be installed with cranes or scaffold forklifts, and can go on spread foundations or steel piers instead of concrete and in problematic soils like sand or landfills. 6 P V M a n u f a c t u r i n g
I S S U E N ° 1 3 S E P T E M B E R 2 0 1 1 ZenithSolar expects to ship 1MW this year, two 10MW projects in pipeline Also now starting to ship systems for multiple new projects is Israel’s ZenithSolar, whose unique watercooled HCPV systems also supply significant amounts of hot water at 75°-80°C or more, hot enough for industrial as well as household uses. Now that the three-year-old company’s 250kW demonstration system at Kibbutz Yavne in Israel has been up and running for about 18 months, a half dozen other customers are stepping up to try the systems— perhaps a sign of the growing maturity of the HCPV sector. Zenith started shipping its first products to projects outside of Israel in March. It now has projects in the pipeline in Australia, Gulf states, Asia and Italy, for various applications that need a lot of hot water, ranging from hospitals to utility central heating plants to water desalinization projects. CEO Roy Segev says the company expects to ship a total of 1.2MW by the end of the year. These wattage figures totals include roughly one third direct production of electricity, roughly two-thirds the thermal energy of the hot water. The ZenithSolar system was designed for cogeneration, giving up some electrical efficiency in the interests of operating at higher temperature to create the extremely hot water needed for industrial applications. The dish mirror optics focus 850x-900x suns on a dense array of cells developed with Azur Space. The cell array is attached to a microchannel heat exchanger, similar to those used in the automotive industry, which heats the pressurized cooling water to close to 100°C so it can be piped away for other uses. That means the cell itself has to operate at a dauntingly high ~120°C, but Segev argues that the cells are rated to survive under these high temperatures, albeit with some loss of efficiency. Company materials also note that the cell array can be swapped out to upgrade the system later. Key to the technology, says Segev, is the company’s high temperature transparent encapsulation paste, which seals the glass directly to the cells to protect them from degradation from air or humidity. The trackers can be placed close together because they can tolerate some shading, as the optics consist of multiple rectangular facets, each about the size of the receiver array, and each independently continues to focus its light on the array, so any shading only reduces the concentration by that of the shaded facets. Like other companies in this young sector, as volumes have increased ZenithSolar has outsourced production of more of its initially internally designed and produced components. “A lot of customers were waiting to see the Yanev data base,” says Segev, referring to the demonstration project at the Israeli town of ~1000 that gets almost all its household hot water from the HCPV system, as well as all the hot water needed for its agricultural ZenithSolar parabolic dish system (Courtesy of ZenithSolar) P V M a n u f a c t u r i n g 7
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September 2011 - I-Micronews

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