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Novel Scanning Lens Instrument for Evaluating Fresnel Lens Performance: Equipment Development and Initial Results (Presentation)

Description: A system dedicated to the optical transmittance characterization of Fresnel lenses has been developed at NREL, in collaboration with the UPM. The system quantifies the optical efficiency of the lens by generating a performance map. The shape of the focused spot may also be analyzed to understand change in the lens performance. The primary instrument components (lasers and CCD detector) have been characterized to confirm their capability for performing optical transmittance measurements. Measurements performed on SoG and PMMA lenses subject to a variety of indoor conditions (e.g., UV and damp heat) identified differences in the optical efficiency of the evaluated lenses, demonstrating the ability of the Scanning Lens Instrument (SLI) to distinguish between the aged lenses.
Date: July 1, 2013
Creator: Herrero, R.; Miller, D. C.; Kurtz, S. R.; Anton, I. & Sala, G.
Partner: UNT Libraries Government Documents Department

Advanced reflector materials for solar concentrators

Description: This paper describes the research and development program at the U.S. National Renewable Energy Laboratory (NREL) in advanced reflector materials for solar concentrators. NREL's research thrust is to develop solar reflector materials that maintain high specular reflectance for extended lifetimes under outdoor service conditions and whose cost is significantly lower than existing products. Much of this work has been in collaboration with private-sector companies that have extensive expertise in vacuum-coating and polymer-film technologies. Significant progress and other promising developments will be discussed. These are expected to lead to additional improvements needed to commercialize solar thermal concentration systems and make them economically attractive to the solar manufacturing industry. To explicitly demonstrate the optical durability of candidate reflector materials in real-world service conditions, a network of instrumented outdoor exposure sites has been activated.
Date: October 1, 1994
Creator: Jorgensen, G.; Williams, T. & Wendelin, T.
Partner: UNT Libraries Government Documents Department

Optimal Heat Collection Element Shapes for Parabolic Trough Concentrators

Description: For nearly 150 years, the cross section of the heat collection tubes used at the focus of parabolic trough solar concentrators has been circular. This type of tube is obviously simple and easily fabricated, but it is not optimal. It is shown in this article that the optimal shape, assuming a perfect parabolic figure for the concentrating mirror, is instead oblong, and is approximately given by a pair of facing parabolic segments.
Date: November 15, 2007
Creator: Bennett, C
Partner: UNT Libraries Government Documents Department

Method and apparatus for aligning a solar concentrator using two lasers

Description: A method and apparatus are provided for aligning the facets of a solar concentrator. A first laser directs a first laser beam onto a selected facet of the concentrator such that a target board positioned adjacent to the first laser at approximately one focal length behind the focal point of the concentrator is illuminated by the beam after reflection thereof off of the selected facet. A second laser, located adjacent to the vertex of the optical axis of the concentrator, is used to direct a second laser beam onto the target board at a target point thereon. By adjusting the selected facet to cause the first beam to illuminate the target point on the target board produced by the second beam, the selected facet can be brought into alignment with the target point. These steps are repeated for other selected facets of the concentrator, as necessary, to provide overall alignment of the concentrator.
Date: October 5, 2000
Creator: Diver, Richard Boyer Jr.
Partner: UNT Libraries Government Documents Department

Markets for concentrating solar power

Description: The report describes the markets for concentrating solar power. As concentrating solar power technologies advance into the early stages of commercialization, their economic potential becomes more sharply defined and increasingly tangible.
Date: April 1, 1998
Partner: UNT Libraries Government Documents Department

Side-by-Side Comparisons of Evacuated Compound Parabolic Concentrator and Flat Plate Solar Collector Systems

Description: Three liquid-based solar heating systems employing different types of solar collectors were tested side by side near Chicago, Illinois for one year. The three different types of collectors were: (1) a flat plate collector with a black-chrome coated absorber plate and one low-iron glass cover; (2) an evacuated-tube compound parabolic concentrator (CPC) with a concentration ratio of 1.1, oriented with tubes and troughs along a north-south axis; and (3) an evacuated-tube CPC collector with a concentration ratio of 1.3 and one low-iron glass cover, with tubes and troughs oriented along an east-west axis. Results indicate that the flat plate collector system was the most efficient during warm weather, but the CPC systems were more efficient during cold weather, but the CPC systems were more efficient during cold weather, and the CPC systems operated under conditions too adverse for the flat plate collector. The computer simulation model ANSIM was validated by means of the side-by-side tests. The model uses analytical solutions to the storage energy balance. ANSIM is compared with the general simulation TRNSYS.
Date: October 1983
Creator: McGarity, Arthur E.; Allen, John W. & Schertz, William W.
Partner: UNT Libraries Government Documents Department

Luminescent solar concentrator development: Final subcontract report, 1 June 1982-31 December 1984

Description: An investigation of luminescent solar concentrators (LSCs) was begun by the US Department of Energy (DOE) at Owens-Illinois, Inc., in 1978. Experimental and theoretical results of that investigation are summarized in this report. An assessment of the LSC technology was compiled to provide a concise description to guide future research in this field. Since 1978, tremendous progress was made in the development of this device as a practical nonimaging concentrator for achieving solar concentration ratios on the order of 10X. The two most important technical achievements appear to be first, the understanding that dye self-absorption of radiated energy is not as serious a problem as originally thought; and second, the demonstration that organic dyes in polymeric hosts are capable of surviving outdoors in bright sunlight for years without serious degradation. System efficiencies approaching 4% have been achieved for photovoltaic conversion and theoretical efficiencies on the order of 9% appear feasible for large-area devices.
Date: April 1, 1987
Creator: Friedman, P.S. & Parent, C.R.
Partner: UNT Libraries Government Documents Department

Software and codes for analysis of concentrating solar power technologies.

Description: This report presents a review and evaluation of software and codes that have been used to support Sandia National Laboratories concentrating solar power (CSP) program. Additional software packages developed by other institutions and companies that can potentially improve Sandia's analysis capabilities in the CSP program are also evaluated. The software and codes are grouped according to specific CSP technologies: power tower systems, linear concentrator systems, and dish/engine systems. A description of each code is presented with regard to each specific CSP technology, along with details regarding availability, maintenance, and references. A summary of all the codes is then presented with recommendations regarding the use and retention of the codes. A description of probabilistic methods for uncertainty and sensitivity analyses of concentrating solar power technologies is also provided.
Date: December 1, 2008
Creator: Ho, Clifford Kuofei
Partner: UNT Libraries Government Documents Department

Advanced process development for high reflector coatings on solar concentrator panels. Final letter report

Description: Objectives were to develop and demonstrate the manufacturing process for vacuum deposition of low-cost thin-film high reflectance coatings onto large solar concentrator panels; demonstrate thin-film deposition processes for commercialization of this technology by United Solar Technologies (UST); apply reflective coatings to solar concentrator panels for prototype application by UST.
Date: October 1, 1996
Creator: Martin, P.M.; Stewart, C.D.; Bennett, W.D. & Johnston, J.W.
Partner: UNT Libraries Government Documents Department

Lithographic antennas for enhancement of solar cell efficiency

Description: This report documents proof-of-concept demonstration of the use of lithographic antennas for enhancement of solar-cell efficiency. A micro-sized lithographic antenna array was theoretically modeled, designed and fabricated. Experimental research was performed to validate the ability of the antenna array to concentrate infrared and visible energy onto photovoltaic (PV) materials. The research will serve as the basis for the design of a miniature power source for remote sensors.
Date: April 1, 1998
Creator: Kotter, D.K. & Boreman, G.
Partner: UNT Libraries Government Documents Department

Development of the SEA Corporation Powergrid{trademark} photovoltaic concentrator

Description: This report covers the three phase effort to bring the SEA Corporation`s Powergrid{trademark} from the concept stage to pilot production. The three phases of this contract covered component development, prototype module development, and pilot line production. The Powergrid is a photovoltaic concentrator that generates direct current electricity directly from sunlight using a linear Fresnel lens. Analysis has shown that the Powergrid has the potential to be very low cost in volume production. Before the start of the project, only proof of concept demonstrations of the components had been completed. During the project, SEA Corporation developed a low cost extruded Fresnel lens, a low cost receiver assembly using one sun type cells, a low cost plastic module housing, a single axis tracking system and frame structure, and pilot production equipment and techniques. In addition, an 800 kW/yr pilot production rate was demonstrated and two 40 kW systems were manufactured and installed.
Date: March 1998
Creator: Kaminar, N.; Curchod, D.; Daroczi, S.; Walpert, M.; Sahagian, J. & Pepper, J.
Partner: UNT Libraries Government Documents Department

Final project report - CRADA with United Solar Technologies and Pacific Northwest Laboratory (PNL-021): Thin film materials for low-cost high performance solar concentrators

Description: The objectives of this project were as follows: To develop and evaluate promising low-cost dielectric and polymer-protected thin-film reflective metal coatings to be applied to preformed continuously-curved solar reflector panels to enhance their solar reflectance, and to demonstrate protected solar reflective coatings on preformed solar concentrator panels. The opportunity for this project arose from a search by United Solar Technologies (UST) for organizations and facilities capable of applying reflective coatings to large preformed panels. PNL was identified as being uniquely qualified to participate in this collaborative project.
Date: March 1, 1995
Creator: Martin, P.M.; Affinito, J.D.; Gross, M.E. & Bennett, W.D.
Partner: UNT Libraries Government Documents Department

Sandwich Construction Solar Structural Facets

Description: Silver/glass mirrors have excellent optical properties but need a method of support in order to be used in concentrating solar thermal systems. In collaboration with the Cummins dish/Stirling development program, they started investigating sandwich construction as a way to integrate silver/glass mirrors into solar optical elements. In sandwich construction, membranes such as sheet metal or plastic are bonded to the front and back of a core (like a sandwich). For solar optical elements, a glass mirror is bonded to one of the membranes. This type of construction has the advantages of a high strength-to-weight ratio, and reasonable material and manufacturing cost. The inherent stiffness of sandwich construction mirror panels also facilitates large panels. This can have cost advantages for both the amount of hardware required as well as reduced installation and alignment costs. In addition, by incorporating the panels into the support structure reductions in the amount of structural support required are potentially possible.
Date: December 22, 1998
Creator: Diver, R. B. & Grossman, J.W.
Partner: UNT Libraries Government Documents Department

Solartrak{trademark} controller developments for today`s applications

Description: The SolarTrak{trademark} array tracking controller, originally developed and licensed by Sandia National Laboratories as a low-cost, high-accuracy, reliable controller for photovoltaic (PV) concentrator arrays, has undergone significant development to make tracking accessible to a much broader segment of the PV market. Hardware and software improvements (1) reduce power consumption for PV/battery- powered applications, (2) enable the controller to connect directly with low-cost, off-the-shelf, television satellite dish actuators, (3) enable on-site setup without an additional input board, (4) increase clock accuracy by providing daily and weekly adjustments to the on board clock, and (5) include a low-cost wind stow sensor. The result is a stand-alone tracking system sufficiently low cost and reliable to make 1-kW tracking systems practical for flat plate and concentrating arrays. Results of a year of testing are presented showing clock accuracy better than a minute per year can be maintained.
Date: December 31, 1995
Creator: Maish, A.B.; O`Neill, M.; West, R. & Shugar, D.S.
Partner: UNT Libraries Government Documents Department

Solar kinetics` photovoltaic concentrator module and tracker development

Description: Solar Kinetics, Inc., has been developing a point-focus concentrating photovoltaic module and tracker system under contract to Sandia National Laboratories. The primary focus of the contract was to achieve a module design that was manufacturable and passed Sandia`s environmental testing. Nine modules of two variations were assembled, tested, and characterized in Phase 1, and results of these tests were promising, with module efficiency approaching the theoretical limit achievable with the components used. The module efficiency was 11.9% at a solar irradiance of 850 W/m{sup 2} and an extrapolated cell temperature of 25{degrees}C. Improvements in module performance are anticipated as cell efficiencies meet their expectations. A 2-kW tracker and controller accommodating 20 modules was designed, built, installed, and operated at Solar Kinetics` test site. The drive used many commercially available components in an innovative arrangement to reduce cost and increase reliability. Backlash and bearing play were controlled by use of preloaded, low slip-stick, synthetic slide bearings. The controller design used a standard industrial programmable logic controller to perform ephemeris calculations, operate the actuators, and monitor encoders.
Date: November 1, 1995
Creator: White, D.L. & Howell, B.
Partner: UNT Libraries Government Documents Department

Development and Demonstration of Compound Parabolic Concentrators for Solar Thermal Power Generation and Heating and Cooling Applications, Progress Report: July-December 1975

Description: Progress report describing the development of Compound Parabolic Concentrators (CPC). A tenfold concentrator with a cavity receiver was constructed and tested. The optical efficiency was very good (65 percent), but the thermal performance was degraded by heat losses of the cavity receiver. A summary of the results of subcontracts described in the previous progress report are presented, and the influence of these results on ANL programs is noted.
Date: 1977
Creator: Allen, John W.; Levitz, Norman M.; Rabl, Ari; Reed, Kent A.; Schertz, William W.; Thodos, George et al.
Partner: UNT Libraries Government Documents Department

A Solar District-Heating System Using Seasonal Storage for the Charlestown, Boston Navy Yard Redevelopment Project

Description: A preliminary analysis is presented for a seasonal storage solar heating system for the Charlestown Navy Yard in Boston, Massachusetts. The area occupies a prominent location in the Boston Harbor and is being redeveloped for residential and commercial use. The system makes use of two large, buried concrete storage tanks totaling 5700 cubic meters as a water heat store. Other storage facilities, including a dry dock, offer additional solar opportunities for the navy Yard as the redevelopment progresses. The analysis makes extensive use of MINSUN, a computer performance and economic simulation routine written specifically for solar seasonal storage systems. The system performance and economics are analyzed for different collector types and areas, component costs, exogenous economic conditions, and optional inclusion of a heat pump. System cost-effectiveness is defined in relation to an economic break-even situation with respect to a conventional system, and is presented in terms of a solar premium, which is the incremental cost for the solar system per MWH of conventional fuel displaced. The additional analysis and design considerations necessary before an implementation phase are outlined. System implementation is discussed in terms of the roles of the various parties involved and funding/financing possibilities.
Date: September 1982
Creator: Breger, Dwayne
Partner: UNT Libraries Government Documents Department

Development of a 2f optical performance measurement system

Description: Commercialization of faceted stretched-membrane concentrators has created the need for quality control measurements for facet optical performance. High-volume production scenarios require a test method that is quick, can be performed on the production floor, and does not require laboratory-grade equipment. At Sandia, we are developing an optical test method that can be done in a relatively short period of time, requires little space, uses ``off the shelf`` test equipment, and provides a quantitative measure adequate to address quality control requirements. The test method is based on common ray trace calculations for targets and images at the radius of curvature for spherical and parabolic (f/D > 3) concentrators. The initial development work was done using a monochrome television camera and the beam characterization system. Twenty-four 3-meter facets built for a faceted stretched-membrane dish were characterized using this system. Other smaller facets have also been tested with the system to help establish a correlation with this method and other optical characterization tests. Current work involves adapting a color camera to the system and developing custom software to reduce analysis time and make the system viable for the production floor. This paper discusses the development of the monochrome system, reviews the results of testing, and presents plans for the development of a color system.
Date: December 1, 1993
Creator: Grossman, J. W.
Partner: UNT Libraries Government Documents Department

Mirror alignment and focus of point-focus solar concentrators

Description: Distributed point-focusing solar concentrators are being developed for dish-Stirling systems and other applications. Many of these concentrators make use of faceted mirrors that have to be accurately aligned. Some of the solar concentrator designs use stretched-membrane facets that also require focusing. Accurate mirror alignment and focus of faceted solar concentrators have two benefits. First, the concentration ratio of the concentrator/receiver (collector) system is improved with accurate alignment and focus. The receiver aperture diameter can therefore be smaller, thereby reducing thermal losses from the receiver and improving the overall efficiency of the collector. Second, and perhaps more importantly, flux intensities on the receiver can be sensitive to facet alignment and focus. In this paper, the theory and practical application of an alignment and focusing technique are presented. In the technique, light from an artificial source is reflected from the concentrator`s facets to a target. From basic geometric principles, the shape and location of the reflected light on the target can be predicted. Alignment is accomplished by adjusting the facets aim so that the reflected image falls on the predetermined location. To focus a stretched-membrane facet, the reflected image size is adjusted to match that of the target. The governing equations used to draw the alignment targets are developed and the practical application of the technique to the alignment and focus of the Cummins Power Generation, Inc. CPG-460 are presented. Alignment uncertainty associated with this technique on the CPG-460 is also discussed.
Date: November 1, 1994
Creator: Diver, R. B.
Partner: UNT Libraries Government Documents Department

Vacuum deposited polymer/silver reflector material

Description: Weatherable, low cost, front surface, solar reflectors on flexible substrates would be highly desirable for lamination to solar concentrator panels. The method to be described in this paper may permit such reflector material to be fabricated for less than 50 cents per square foot. Vacuum deposited Polymer/Silver/Polymer reflectors and Fabry-Perot interference filters were fabricated in a vacuum web coating operation on polyester substrates. Reflectivities were measured in the wavelength range from .4 {mu}m to .8 {mu}m. It is hoped that a low cost substrate can be used with the substrate laminated to the concentrator and the weatherable acrylic polymer coating facing the sun. This technique should be capable of deposition line speeds approaching 1500 linear feet/minute. Central to this technique is a new vacuum deposition process for the high rate deposition of polymer films. This polymer process involves the flash evaporation of an acrylic monomer onto a moving substrate. The monomer is subsequently cured by an electron beam or ultraviolet light. This high speed polymer film deposition process has been named the PML process - for Polymer Multi-Layer.
Date: July 1, 1994
Creator: Affinito, J.; Martin, P.; Gross, M. & Bennett, W.
Partner: UNT Libraries Government Documents Department

Investigation into Spectral Parameters as they Impact CPV Module Performance

Description: The CPV industry is well aware that performance of triple junction cells depends on spectral conditions but there is a lack of data quantifying this spectral dependence at the module level. This paper explores the impact of precipitable water vapor, aerosol optical depth (AOD), and optical air mass on multiple CPV module technologies on-sun in Golden, CO.
Date: March 1, 2011
Creator: Muller, M.; Marion, B.; Kurtz, S. & Rodriguez, J.
Partner: UNT Libraries Government Documents Department


Description: The development of microsatellites requires the development of engines to modify their orbit. It is natural to use solar energy to drive such engines. For an unlimited energy source the optimal thruster must use a minimal amount of expendable material to minimize launch costs. This requires the ejected material to have the maximal velocity and, hence, the ejected atoms must be as light as possible and be ejected by as high an energy density source as possible. Such a propulsion can be induced by pulses from an ultra-short laser. The ultra-short laser provides the high-energy concentration and high-ejected velocity. We suggest a microthruster system comprised of an inflatable solar concentrator, a solar panel, and a diode-pumped fiber laser. We will describe the system design and give weight estimates.
Date: February 5, 2010
Creator: Rubenchik, A M; Beach, R; Dawson, J & Siders, C W
Partner: UNT Libraries Government Documents Department

Fourth-generation photovoltaic concentrator system development

Description: In 1991, under a contract with Sandia for the Concentrator Initiative, the ENTECH team initiated the design and development of a fourth-generation concentrator module. In 1992, Sandia also contracted with ENTECH to develop a new control and drive system for the ENTECH array. This report documents the design and development work performed under both contracts. Manufacturing processes for the new module were developed at the same time under a complementary PVMaT contract with the National Renewable Energy Laboratory. Two 100-kW power plants were deployed in 1995 in Texas using the newly developed fourth-generation concentrator technology, one at the CSW Solar Park near Ft. Davis and one at TUE Energy Park in Dallas. Technology developed under the Sandia contracts has made a successful transition from the laboratory to the production line to the field.
Date: October 1, 1995
Creator: O`Neill, M. J. & McDanal, A. J.
Partner: UNT Libraries Government Documents Department