Search

In this paper we present a comprehensive outdoor experimental characterization of the first modules assembled using the Achromatic Doublet on Glass (ADG) Fresnel lens technology. First, only the elementary units comprising one lens and one cell are investigated: the electrical performance is measured varying the cell-lens distance in order to identify the optimal focal distance. Second, a mono-module (module composed of one lens and one solar cell) has been assembled and installed on a two-axis tracker where it has been continuously measured between June and October 2018. Also, a mono-module including conventional Silicone on Glass (SoG) Fresnel lenses has been assembled and used as benchmark. Results demonstrated that the achromatic design of the ADG lenses used as Primary Optical Elements (POE) provides a significantly reduced temperature dependency of the module performance. The performance is maintained constant throughout the whole measurement period enhancing the energy output over time. [ABSTRACT FROM AUTHOR]

A key aspect in the performance of a concentrator photovoltaic (CPV) module is a proper alignment between the optics and the photovoltaic solar cell. This work proposes a novel method for measuring misalignments in CPV at different levels, considering misalignments between units at module level or misalignments between modules at tracker level. The method is based on images acquisition (using a CCD camera) and its processing. To validate the method, a CPV module has been measured and results have been compared with a proven method given by the Module Optical Analyzer (MOA). [ABSTRACT FROM AUTHOR]

Concentrator photovoltaic usually embeds multi-junction solar cells, which exhibit high spectral sensitivity due to the internal series connection of the sub-cells. The use of so-called isotype or component cells with the same spectral response as the corresponding sub-cell, is widely applied for characterizing the spectral content of the impinging irradiance. These isotype sensors can be substituted by the multi-junction cells themselves, which are inherently spectrally tuned to any evolution of the multi-junction technology. To convert a multi-junction cell in a spectral sensor, it is necessary to add bias light within the spectral response of all but one of the sub-cells to saturate the corresponding junctions, so the nonsaturated limits the current under any specified impinging spectrum. This paper shows indoor and outdoor side-by-side comparison of the so-called pseudo isotypes, based on a triple-junction solar cell, and genuine isotypes. The conditions to ensure an accurate spectral response, particularly for the bottom pseudo-isotype, are presented and discussed. [ABSTRACT FROM AUTHOR]

The manufacturing method developed to obtain Achromatic Doublet on Glass (ADG) Fresnel lenses results in an optical system with high concentration while maintains a reduced cost. Recent improvements in the manufacturing process are presented in this paper. First, an adhesion promoter has been used in order to enhance adhesion between plastic and elastomer interface. This avoids the efficiency drop caused by delamination due to changes in temperature through the day. . Second, the whole lamination process has been almost completely automatized, requiring the intervention of a human operator only to place the lens inside the laminator. Finally, a new injection mold based on nickel stamper technology has been manufactured improving the geometrical characteristics of the plastic element of the lens (lower draft angle and tip rounding). [ABSTRACT FROM AUTHOR]

A model to evaluate the performance of high concentrator photovoltaics (HCPV) modules (that generates current-voltage curves) has been applied together with a Monte Carlo approach to obtain a distribution of modules with a given set of characteristics (e.g., receivers electrical properties and misalignments within elementary units in modules) related to a manufacturing scenario. In this paper, the performance of CPV systems (tracker and inverter) that contain the set of simulated modules is evaluated depending on different system characteristics: inverter configuration, sorting of modules and bending of the tracker frame. Thus, the study of the HCPV technology regarding its angular constrains is fully covered by analyzing all the possible elements affecting the generated electrical power. [ABSTRACT FROM AUTHOR]

The experimental method to determine the spectrally-resolved optical efficiency of concentrating optics is described in this paper. The measurement uses a multi-junction solar cell as light sensor and a series of band-pass filters to isolate the optical performance of different narrow spectral bands throughout the spectrum of interest. Additional bias light is provided to saturate the subcells whose spectral response is out of the transmittance of every band-pass filter. The method allows the characterization of the combined transmittance, reflectance and absorbance of every material composing the optics including optical couplers and thin layers such as antireflective coatings. The two application cases included illustrate the potential of this novel characterization technique. Firstly, a novel refractive concentrator, the Achromatic Doublet on Glass (ADG) Fresnel lens is measured. Secondly, the method is applied to analyze the degradation of outdoor exposed glass molded Secondary Optical Elements (SOE). [ABSTRACT FROM AUTHOR]

In this paper we present a comprehensive experimental characterization of Achromatic Doublet on Glass (ADG) Fresnel lenses. When compared to a Silicone on Glass (SoG) Fresnel lens, the ADG Fresnel lens shows higher tolerance to displacements of the lens with respect to the optimal lens-to-cell distance. Furthermore, lower sensitivity of the ADG Fresnel lens to temperature variations has been experimentally proven. [ABSTRACT FROM AUTHOR]

This article describes the procedure proposed by IES-UPM to measure the optical efficiency and the irradiance of the focused spot of a primary optic for concentrator PV (CPV). The method using a broadband source (solar simulator) with a solar cell as the sensor and analysis of the focused spot recorded by a camera is described in detail here to convey the details of the optical characterization in the emerging IEC 62989 technical specification. Special emphasis is placed in noting the main sources of error and the accuracy of the measurement method. As an example, the main outcomes attained in the characterization of a set of Fresnel lenses are reported. [ABSTRACT FROM AUTHOR]

The tuning of the assembly line of concentrated photovoltaic (CPV) modules is an important task to ensure that the efficiency of modules made at the production line is as high as those fabricated in the development phase. A solar simulator for CPV and a module optical analyzer (MOA) are proposed to be used in production to improve the quality of the assembling process (both during the tuning of the production line and once it is completed). Moreover, the usefulness of performing a quality control based on maximum power and optical pointing of modules is discussed by performing a deep analysis of some modules manufactured in the production line and characterized both indoors and outdoors. [ABSTRACT FROM AUTHOR]

Synthetic and empirical data have been used to explore the influence of spectral mismatch between MJ cell technologies on outdoor CPV module rating uncertainty. Calibration biases are attenuated by tightly filtering spectral conditions to a spectral matching ratio (SMR) of 1 ± 2.5%. The sensitivity of calibrated current to spectral deviations greatly depends on the direction and distribution of the deviations on the SMR space. [ABSTRACT FROM AUTHOR]

Spectral variation of solar irradiance can be analyzed by the means of component cells, being useful for multi junction (MJ) and concentrator photovoltaics (CPV) characterization by the use of component cells derived spectral indexes, namely, spectral matching ratios (SMRs). When enough spectral data is available, a location can be also characterized and a MJ solar cell can be locally tuned. The AERONET network of ground-based sun photometers is employed to obtain the atmosphere parameters for 34 sites worldwide. To conclude, the SMR indexes are obtained for every location, and a comparative analysis is completed for four architectures of MJ solar cells technologies (two lattice match and two metamorphic). Based on this information, some cluster of locations that share similar spectral features arise. [ABSTRACT FROM AUTHOR]

This paper presents the project Concentrating Photovoltaic modules using advanced technologies and cells for highest efficiencies (CPVMatch), which is funded from the European Union's Horizon 2020 research and innovation programme. V multi-junction solar cells and CPV modules. Concerning cells, novel wafer bonded four-junction solar cells made of GaInP/GaAs//GaInAs/Ge are optimized with the target of reaching 48% efficiency under concentration at the end of the project. Moreover, multi-junction solar cell technologies with advanced materials - like ternary IV element mixtures (i.e. SiGeSn) and nanostructured anti-reflective coatings - are investigated. Concerning CPV modules the project focuses on both Fresnel-based and mirror-based technologies with a target efficiency of 40% under high concentrations beyond 800x. Achromatic Fresnel lenses for improved light management without secondary optics are investigated. In addition, smart, mirror-based HCPV modules are developed, which include a new mirror-based design, the integration of high efficiency, low cost DC/DC converters and an intelligent tracking sensor (PSD sensor) at module level. A profound life-cycle and environmental assessment and the development of adapted characterization methods of new multi-junction cells and HCPV modules complete the work plan of CPVMatch. [ABSTRACT FROM AUTHOR]

In this paper we present a novel manufacturing method to produce achromatic Fresnel lenses for photovoltaic application. These achromatic lenses are capable of reaching a concentration factor three times higher than that attained by a conventional Silicone-on-Glass (SOG) Fresnel lens. The manufacturing method presented to fabricate the achromatic lens, which we refer to as Achromatic Doublet on Glass (ADG) Fresnel lens, is simple, cost-effective and highly scalable. A comprehensive ray-tracing analysis and its comparison with experimental results is presented in this work. [ABSTRACT FROM AUTHOR]

Secondary optical elements (SOEs) are used in Concentrator Photovoltaic (CPV) modules to allow the concentration ratio to exceed those typically achievable by Fresnel lenses, reducing cell costs, without sacrificing tolerance to tracking errors. One option is a "dome" SOE: a simple, single surface refractive optic that images the primary lens onto the cell while immersing it. In this article, we explore the limits of this type of SOE and propose an evolved version, which we dub the Hybrid Dome Reflector (HDR), which offers advantages especially for high concentration modules with large cells, where reflective secondaries do not offer sufficient acceptance angle, but other dielectric secondaries, such as the Dielectric Totally Internally Reflecting Concentrator DTIRC, may be too large for economical manufacture. We discuss aspects of HDR design and share selected ray-tracing simulations and experimental results. We show that the new HDR design improves acceptance angle and tolerances to manufacturing error and lens temperature as compared to a reflective SOE built while offering similar efficiencies. [ABSTRACT FROM AUTHOR]

At any moment, organizations may face a range of crises, from global pandemics and economic depressions to business catastrophes -- all of which can strain operational processes and performance (Wright et al., 2020; Williams et al., 2017). Research suggests that crises can also engender positive organizational growth, learning, and identity (Fink et al., 1971), which may trickle down to the group and individual levels. However, the dynamics underpinning the interplay of organizational-, group-, and individual-level shifts in meaning of work amidst "a backdrop of change and 'outside' elements" (Cheney & Thompkins, 1987: 5) remain largely underexplored. Research that addresses meaning of work in times of crisis and change not only helps to close this gap, but also enables scholars to understand when and why thriving (vs. decline) amidst crisis occurs. This symposium brings together five field-based investigations to focus on the interplay of individual, group, and organizational dynamics around the meaning of work in the context of crisis. First, Jiang and Cho quantitatively examine the macro effects of a societal level crisis and how a societal crisis can trigger a personal one in terms of individuals' meaning of work; in particular, they uncover that one's meaning of work can be temporarily unsettled by an external, societal-level crisis. Second, Gorges explores people's experiences of downshifting--defined as a voluntary long-term change to spend less time on work and more time on leisure--following a large global crisis, namely, the COVID-19 pandemic. Third, Eun examines how callings are expressed in crises, such as the COVID-19 crisis, illuminating not only the prevailing prosocial nature of callings, but also revealing work orientations as an important input to crisis behaviors. Fourth, Sala considers the effects of occupational level threats and how they affect individuals' sense of self and meaning. Finally, Rocheville and colleagues unpack the effects of individual-level crises in illuminating how workers in chronic pain create and/or sustain a positive meaning of work. Sally Maitlis, a distinguished scholar of how people make sense of challenges and trauma at work in meaningful ways, will serve as the discussant to highlight both theoretical and practical implications as well as future research directions. Crisis within a Crisis: The Destabilizing Effect of Societal Crises on Individual Work Orientation Author: Winnie Jiang; INSEAD Author: Yuna Cho; HKU Business School, The U. of Hong Kong Downshifting: A Voluntary Career Shift to Reduce Work Hours Author: Megan Gorges; Harvard Business School Putting Callings to the Test: Prosocial Behaviors in a Crisis Associated with Calling Orientations Author: Eunice Eun; Yale School of Management Out of Service? Individual Experiences of an Occupational Identity Existential Threat Author: Gabriel Robert Sala; Northeastern U. Chronic Pain as a Crisis: The Role of Work-Body Ideologies in Sustaining Positive Meaning of Work Author: Kimberly Rocheville; Creighton U. Author: Elana Feldman; UMass Lowell Author: Beth Schinoff; Boston College Author: Njoke Thomas; Boston College [ABSTRACT FROM AUTHOR]

This paper presents the mechanisms of efficiency losses that have to do with the non-uniformity of the irradiance over the multi-junction solar cells and different measurement techniques used to investigate them. To show the capabilities of the presented techniques, three different concentrators (that consist of an acrylic Fresnel lens, different SOEs and a lattice matched multi-junction cell) are evaluated. By employing these techniques is possible to answer some critical questions when designing concentrators as for example which degree of non-uniformity the cell can withstand, how critical the influence of series resistance is, or what kind of non-uniformity (spatial or spectral) causes more losses. [ABSTRACT FROM AUTHOR]

In the frame of the European project SOPHIA, a spectral network based on component (also called isotypes) cells has been created. Among the members of this project, several spectral sensors based on component cells and collimating tubes, so-called spectroheliometers, were installed in the last years, allowing the collection of minuteresolution spectral data useful for CPV systems characterization across Europe. The use of spectroheliometers has been proved useful to establish the necessary spectral conditions to perform power rating of CPV modules and systems. If enough data in a given period of time is collected, ideally a year, it is possible to characterize spectrally the place where measurements are taken, in the same way that hours of annual irradiation can be estimated using a pyrheliometer. [ABSTRACT FROM AUTHOR]

Air Mass and atmosphere components (basically aerosol (AOD) and precipitable water (PW)) define the absorption of the sunlight that arrive to Earth. Radiative models such as SMARTS or MODTRAN use these parameters to generate an equivalent spectrum. However, complex and expensive instruments (as AERONET network devices) are needed to obtain AOD and PW. On the other hand, the use of isotype cells is a convenient way to characterize spectrally a place for CPV considering that they provide the photocurrent of the different internal subcells individually. Crossing data from AERONET station and a Tri-band Spectroheliometer, a model that correlates Spectral Mismatch Ratios and atmospheric parameters is proposed. Considering the amount of stations of AERONET network, this model may be used to estimate the spectral influence on energy performance of CPV systems close to all the stations worldwide. [ABSTRACT FROM AUTHOR]

CPV receivers are made of materials with very different lineal expansion coefficients. Strong variations in DNI due to the passage of clouds can cause sudden temperature changes that creates mechanical stress. For common solder and metal filled polymers the plastic limit could be reached causing substantial fatigue. The best forecast of receiver reliability is therefore achieved by applying an intermittent light source with nominal irradiance level and a number of cycles equal to the expected cloud passages for a given site. The UPM has developed specialized equipment, dubbed the LYSS (Light cYcling Stressing Source), for carrying out such experiments. The small thermal capacity of receivers allows simulating more than 25000 cycles per week. The number of deep transients expected for Madrid in 30 years operation, based on available data, is about 45000. We are currently using the system to cycle a "Ge/Ag Epoxy/ aluminum" receiver, which shows no degradation after 20000 cycles. The equipment can cast up to 200 and 70 W/cm2 on 0.1 and 1 cm² cells, respectively. [ABSTRACT FROM AUTHOR]

A full Hybrid lighting-CPV prototype has been assembled. This new concept mixes a classical CPV module with the production of light for illumination without a double conversion (solar energy to electricity and electricity to light) allowing a higher efficiency to the whole system. The present prototype is based on a commercial CPV module that has been adapted in order to be hybrid, adjusting the receivers to pass the fibers into the module, inserting a holder to adjust x, y and z position of the fibers and changing the original parquet of lenses by a bifocal one composed most of the original lenses and the inclusion of other lenses in the position of the corners. Results show that with a minimal loss in the CPV part, a luminous flux is obtained that can be used to illuminate. Adding an additional electrical lamp and a light sensor that enables this lamp when no light from the sun is received, a 38% saving on lighting electricity is expected in Madrid during a year. [ABSTRACT FROM AUTHOR]

Thermal characterization of Concentrating Photovoltaics (CPV) modules and arrays is needed to determine their performance and modelling of energy forecast. Module-ambient thermal resistance is easily obtained from its definition but the cell-module thermal resistant needs to be estimated from indirect procedures, two of them are presented in this paper. In addition, an equivalent parameter is defined, the Concentrator Nominal Operating Module/Cell Temperature (CNOMT/CNOCT), the temperature at Concentrator Standard Operating Conditions (CSOC). Definitions and expression to relate (CNOMT/CNOCT) to thermal resistances are presented, plus several examples of estimations from real operating arrays. [ABSTRACT FROM AUTHOR]

The usefulness of the module optical analyzer when identifying module defects on production line is presented in this paper. Two different case studies performed with two different kind of CPV modules are presented to show the use of MOA both in IES-UPM and Daido Steel facilities. [ABSTRACT FROM AUTHOR]

This paper presents the experimental characterization of the efficiency thermal sensitivity of a system whose optics is composed of a silicone on glass Fresnel lens and a secondary element also made of silicone. In addition, some indications are provided on the adequate chemical formulation of the silicone that withstands longtime outdoor exposure under concentrated light without showing appreciable degradation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In order to complement ISFOC's characterization capabilities, a Helios 3198 CPV Solar Simulator was installed in summer 2010. This Solar Simulator, based on a parabolic mirror and a high-intensity, small area Xenon flash lamp was developed by the Instituto de Energía Solar in Madrid [1] and is manufactured and distributed by Soldaduras Avanzadas [2]. This simulator is used not only for R&D purposes, but as a quality control tool for incoming modules that are to be installed in ISFOC's CPV plants. In this paper we will discuss the results of recent measurements of close to 5000 modules, the entire production of modules corresponding to a small CPV power plant (200 kWp). We scrutinize the resultant data for signs of drift in the measurements, and analyze the light quality before and after, to check for changes in spectrum or spatial uniformity. [ABSTRACT FROM AUTHOR]

A method is presented for estimating the photocurrent of the subcells of a multijunction cell within a concentrator, through the measurement of the cell's short-circuit current under a large sweep of different spectral conditions. The spectrum is monitored by means of a set of component cells matched to the subcells of the concentrator cell. The method allows the calculation of the current-matching or J-ratio of the concentrator cell under any spectrum, and also the identification of losses due to the non-uniformity of the spectrum throughout the solar cell area. For illustration purposes, the method is applied to a concentrator composed of a Fresnel lens that concentrates light over a triple-junction cell 300 times smaller. [ABSTRACT FROM AUTHOR]

Modules are an important part of the CPV system. By pursing, in our objective of a 35% efficiency module, we need to look forward a significant improvement in the state of the art of CPV modules since no commercial module is capable of achieving that efficiency. Achieving this efficiency will require high efficiency cells, progress in the optics lenses that are implemented in these modules, and also integration into module. Basic design of 35 % CPV module is presented considering for practical and rapid industry application. The output is 385 W while its weight is only 18 kg. In spite of its high concentration ratio reaching 1,000 X, it acceptance angle is as high as 1.1 degree. [ABSTRACT FROM PUBLISHER]

Manufactures of Concentration Photovoltaic (CPV) modules share a need for indoor testing, implying an appropriate artificial light source. This source must be highly spatially uniform and have a collimation angle similar to that of the sun. In this work, we report the results of a detailed sensitivity study of these two parameters, in order to provide a quantitative basis for setting the requirements for future simulators and in international standards. [ABSTRACT FROM AUTHOR]

In hybrid Silicone-on-glass Fresnel lenses, an optical silicone is molded onto a glass substrate and forms the Fresnel structure. These lenses offer a cost effective solution as a primary optical element in point-focus concentrator photovoltaic modules, as well as performance advantages. However, these lenses have a high performance variation with temperature due both to the change in index of refraction of silicone as well as to deformations in the facets caused by coefficient of thermal expansion (CTE) mismatch. In this study we perform measurements of the light flux at the focal plane of a family of SOG lenses, varying temperature and lens-to-receiver distances. The effect of varying silicone cure temperature and the depth of the silicone between the lens and the glass substrate on temperature dependence was investigated. A preliminary computer model of this behavior is presented. [ABSTRACT FROM AUTHOR]

The photocurrent produced by a multijunction III-V cell is limited by the component cell of the union which yields the lowest photocurrent. The induced energy losses are quantified by the Spectral Radiation Matching Factor (SRMF), defined as the ratio between the energy produced by a III-V multijunction cell and the energy that could be produced if the subcells were current matched at any moment. Accurate SRMF estimations generally require accurate measurement of solar spectrum. Another method is to measure the spectrum using three 'isotype' cells, or single-junction cells that have the same spectral response as each of the three component cells in the multi-junction stack. That method is validated against photocurrents calculated from spectral measurements (by spectroradiometer) and broadband direct beam measurements (by pyrheliometer). Those comparisons show agreement in the results above 98% under clear-sky conditions. The difference between the two independent SRMF calculations is within 1% margin. The application of this method to the spectral measurements realized in Madrid in 2009 leads to estimate an annual current spectral mismatching of around 7%. [ABSTRACT FROM AUTHOR]

At the core of "creating a better world together" is being able to work side by side, acknowledging our differences and embracing the strengths and challenges of a diverse and inclusive workplace. Recent events have shown how important diversity and inclusion is to societies and organizations: one can still hear the voices echoing in the growing social movements related to #BlackLivesMatter, #TimesUp, #MeToo, and others reminding us that the work of diversity and inclusion is only beginning. Events in the last several years alone have forced organizations to rethink diversity, equity and inclusion efforts, leading in some cases to radical policy and practice changes. Our symposium has two goals: investigate differences in sources of diversity through a set of theoretical and empirical papers; and discussing the possible connections and overlaps between findings to push the boundaries of the diversity and inclusion literature. * Ideal workers and ideal bodies: How workers in pain navigate stigma in an able-bodied workplace * Presenter: Kimberly Rocheville; Creighton U. * Presenter: Elana Feldman; UMass Lowell * Understanding the experiences of formerly incarcerated jobseekers with employment reentry programs * Presenter: Audrey Holm; Boston U. * 'Talking about my Generation': Generational labels and Meaningful work * Presenter: Gabriel Robert Sala; Boston College * Presenter: Greg Fetzer; U. of Liverpool * A Proud Struggle? Alternative Pathways to Professional Dignity Amidst Occupational Inequality * Presenter: Tomi Koljonen; U. of Liverpool * Presenter: Joona Koistinen; Aalto U. School of Business [ABSTRACT FROM AUTHOR]