Analytical modelling of high concentrator photovoltaic modules based on atmospheric parameters

PublishedJournal Article© 2015 Eduardo F. Fernández et al. The goal of this paper is to introduce a model to predict the maximum power of a high concentrator photovoltaic module. The model is based on simple mathematical expressions and atmospheric parameters. The maximum power of a HCPV module is estimated as a function of direct normal irradiance, cell temperature, and two spectral corrections based on air mass and aerosol optical depth. In order to check the quality of the model, a HCPV module was measured during one year at a wide range of operating conditions. The new proposed model shows an adequate match between actual and estimated data with a root mean square error (RMSE) of 2.67%, a mean absolute error (MAE) of 4.23 W, a mean bias error (MBE) of around 0%, and a determination coefficient (R 2) of 0.99.Partial funding for this study was provided through EPSRC funded BioCPV (EP/J000345/1) project. Also, this work is part of the project “Desenvolvemento de novos conceptos baseados en tecnoloxía de concentración fotovoltaica para a produción de enerxía eléctrica adaptados a distintas zonas climáticas,” through the program “Formación Posdoutoral do Plan Galego de Investigación, Innovación e Crecemento 2011–2015 (Plan I2C)” funded by the Xunta de Galicia and by the European Social Fund

Optical modeling of four Fresnel-based high-CPV units

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordHigh Concentrator Photovoltaic (HCPV) units are typically based on the use of Fresnel lenses, refractive secondary optical elements (SOE), and triple-junction (TJ) solar cells. In this work, a detailed optical modeling is applied to analyze the performance of four Fresnel-based HCPV units equipped with different refractive SOEs while considering the subcells current density generation. Wavelength-dependent material properties are utilized while simulating the optical performance. The spectral response of a typical TJ solar cell is also included. This modeling allows to establish the subcell current limitation and the spectral matching ratio, SMR, values in each case. The following SOEs have been used for simulating the HCPV units: (i) Dielectric-cross compound-parabolic-concentrator (DCCPC), (ii) (SIngle-Lens-Optical element) SILO-Pyramid, (iii) Refractive truncated pyramid (RTP) and, (iv) Trumpet. Results show that the HCPV units with SOEs RTP and Trumpet, exhibit bottom subcell current limitation and lowest optical polychromatic efficiency, this is partly due to the irradiance absorption in the bottom cell spectral region and longer optical path length of the concentrated rays within the SOE material. In the case of the HCPV unit with the DCCPC SOE, top and bottom subcells limit the current generation alternatively depending on the misalignment angle of the HCPV unit respect to the simulated sunrays. None of the SMR parameters are equal to 1 under normal alignment of the HCPV units. The short-circuit current density distributions for each subcell in each case are studied under normal alignment and under 1° of misalignment angle.European Regional Development Fund (ERDF) and Spanish Economy Ministry (ENE2013-45242-R and ENE2016-78251-R); Universidad de Jaén (UJA) and Caja Rural de Jaén (UJA2015/07/01). Financial support provided by the Universidad de Jaén Doctoral School

Analysis of high concentrator photovoltaic modules in outdoor conditions: Influence of direct normal irradiance, air temperature, and air mass

The study of high concentrator photovoltaic (HCPV) technology under real conditions is essential to understand its real behavior. The influence of direct normal irradiance (DNI), air temperature (Tair), and air mass (AM) on the maximum power of two HCPV modules was studied for more than three years. Results found are presented in this paper. As expected, the main influence on the maximum power is DNI. Also, Tair has been found to have small influence on the maximum power. Regarding AM, two different behaviors have been found. The maximum power could be considered independent of AM for AM 2, while it decreases with an approximate linear behavior for AM > 2. Also, the maximum power of a HCPV module could be estimated with a linear mathematical fitting based on DNI, Tair, and AMThis work is a part of the project “SIGMPLANTAS: La innovacion en las plantas y modelos de sistemas de Concentracion Fotovoltaica en España,” IPT-2011-1468-920000 supported by the Spanish Science and Innovation Ministry and by the European Regional Development Fund/Fondo Europeo de Desarrollo Regional (ERDF/FEDER)S

Design and characterization of refractive secondary optical elements for a point-focus Fresnel lens-based high CPV system

This is the final version of the article. Available from AIP Publishing via the DOI in this record.Point-focus Fresnel lens-based High Concentrator Photovoltaic (HCPV) systems are usually equipped with refractive secondary optical elements (SOE) in order to improve their performance. Two basic SOE designs are optically modeled and simulated in this work: Domed-Kaleidoscope (D-K) with breaking-symmetry top and SILO (SIngle-Lens-Optical element). Wavelength-dependent optical material properties like refractive index and absorption coefficient, as well as the spectral response of a typical triple-junction (TJ) solar cell, are included in the ray tracing simulations. Moreover, using a CPV Solar Simulator "Helios 3198", both HCPV units are experimentally characterized. The acceptance angle characteristics of both HCPV units, obtained through optical simulations and through indoor characterization, are compared. The acceptance angle characteristic is better for the HCPV unit with the D-K SOE both in simulations and in experimental measurements, showing concordance between simulation and experiment. However, simulation results underestimate the experimental ones concerning the acceptance angle, which will be investigated in future works.European Regional Development Fund (ERDF) and Spanish Economy Ministry (ENE2013-45242-R and ENE2016-78251-R); Universidad de Jaén (UJA) and Caja Rural de Jaén (UJA2015/07/01). Financial support provided by the Universidad de Jaén Doctoral School. The authors also thank Lambda Research Corporation for its donation of TracePro optical software

A >3000 suns high concentrator photovoltaic design based on multiple Fresnel lens primaries focusing to one central solar cell

A high concentrator photovoltaic design is proposed of 5800x geometrical concentration ratio based on multiple primary Fresnel lenses focusing to one central solar cell. The final stage optic is of a novel design, made of a high refractive index (n = ∼1.76), to accept light from four different directions but very easily manufactured. The high geometrical concentration of 5800x was chosen in anticipation of the losses accompanied due to alignment difficulties. Two scenarios are however simulated, one with state of the art optics (achromatic Fresnel lenses and 98% reflective mirrors) and one of standard, relatively cheap optics. An optical efficiency of ∼75% is achieved in simulations if high quality optics are utilised, which gives an optical concentration ratio of just over 4300x. Simulating standard optical constraints with less accurate optics results in an optical efficiency of ∼55% which translates to an optical concentration ratio of ∼3000x. In this way the quality of the optics can be chosen depending on the trade of between cost and efficiency with room for future advanced optics to be incorporated at a later date. The optical efficiency of each component is simulated as well as experimentally measured to ensure the accuracy of the simulations. A theoretical acceptance angle of 0.4° was achieved in ray trace simulations for this design which is considered good for such a high concentration level. The need for achromatic Fresnel lenses is apparent from this study to reach optimum performance and concentration but even 55% optical efficiency results in a >3000x concentration not yet experimentally tested. The solar cells irradiance distribution of the design is also presented along with performance and rough cost comparisons to other systems in the literature. The cost of the optics compared to more complex shaped optics is also given

Scutoids are a geometrical solution to three-dimensional packing of epithelia

As animals develop, tissue bending contributes to shape the organs into complex three-dimensional structures. However, the architecture and packing of curved epithelia remains largely unknown. Here we show by means of mathematical modelling that cells in bent epithelia can undergo intercalations along the apico-basal axis. This phenomenon forces cells to have different neighbours in their basal and apical surfaces. As a consequence, epithelial cells adopt a novel shape that we term “scutoid”. The detailed analysis of diverse tissues confirms that generation of apico-basal intercalations between cells is a common feature during morphogenesis. Using biophysical arguments, we propose that scutoids make possible the minimization of the tissue energy and stabilize three-dimensional packing. Hence, we conclude that scutoids are one of nature's solutions to achieve epithelial bending. Our findings pave the way to understand the three-dimensional organization of epithelial organs

Author Correction: Scutoids are a geometrical solution to three-dimensional packing of epithelia.

The original version of this Article contained an error in ref. 39, which incorrectly cited 'Fristrom, D. & Fristrom, J. W. in The Development of Drosophila melanogaster (eds. Bate, M. & Martinez-Arias, A.) II, (Cold spring harbor laboratory press, 1993)'. The correct reference is 'Condic, M.L, Fristrom, D. & Fristrom, J.W. Apical cell shape changes during Drosophila imaginal leg disc elongation: a novel morphogenetic mechanism. Development 111: 23-33 (1991)'. Furthermore, the last sentence of the fourth paragraph of the introduction incorrectly omitted citation of work by Rupprecht et al. The correct citation is given below. These errors have now been corrected in both the PDF and HTML versions of the Article. Rupprecht, J.F., Ong, K.H., Yin, J., Huang, A., Dinh, H.H., Singh, A.P., Zhang, S., Yu, W. & Saunders, T.E. Geometric constraints alter cell arrangements within curved epithelial tissues. Mol. Biol. Cell 28, 3582-3594 (2017)

Proposal for a combined methodology for renewable energy planning. Application to a Spanish region

The article here presented aims to contribute to renewable energies development at regional level, proposing a methodology for the establishment of strategies needed to reach, in the long term, an energy system more sustainable and mainly based upon autochthonous resources. Current energy planning models are investigated, analysing its convenience to design a sustainable energy system, and a new methodology, that combines three different approaches, is proposed. Such new "hybrid" methodology resumes advantages of territorial strategic planning methods, based upon SWOT analysis, along with characteristics extracted both from Multicriteria decision analysis techniques and expert opinion "Delphi" methods. Nowadays, decisions concerning energy system cannot be consider under one specific criterion. Different implications, energetic, environmental or socioeconomic, derived from changes on energy development make it unavoidable to use tools and techniques that could take into account such multiplicity. It has been also intended to take advantage of the know-how acquired along the territorial strategic planning process carried out in the region to analyse, from year 1997 to 2000. This approach has allowed to integrate, under a unique methodology, tools from energy planning with those one used, and successfully tested, for the elaboration of the strategic plan for Jaén Province. The proposed methodology has been applied to Jaén Province in order to design a renewable energy plan for the region, setting strategic action lines and fixing strategic goals to be met on year 2010 by the provincial energy system. The objective regarding electricity production from renewable resources, on year 2010, is fixed above 1630 GWh, which represents a 43% of the total foreseeable electricity consumption. Overall contribution of renewable sources in provincial energy system is finally set to 28.3%, in terms of final energy.Renewable energy planning MCDA Expert opinion SWOT analysis

High Concentrator PhotoVoltaics efficiencies: Present status and forecast

Photovoltaic devices are in a mature technological stage with a long and wide field experience; but if this source of energy wants to compete against other renewable energy sources or even to get into the traditional energy generation system, it is necessary a novel scientific progress in the behavior of these photovoltaic systems. In this challenge is where High Concentrator Photovoltaic technology can have a main role, as it has proved, in the last researches published, to have the potential to achieve high levels of energy conversion performance. In this paper, it is described a brief summary of the CPV state of the art, as well as it is forecast some efficiencies values up to 2015, where a CPV module could reach 40% of efficiency, while the global CPV system could achieve approximately a 32%.Concentrator Photovoltaics Efficiency Performance