A cooling system for a hybrid PV/thermal linear concentrator

This paper presents the thermal evaluation of an evacuated PVT collector designed to operate under concentrated radiation (15 suns). Finite volume 3D numerical computations have been carried out in order to study the thermal characteristics of different rectangular cross section aluminium pipes and to test the performance of the PVT collector with several laminar flow rates. Experiments with the same laminar flows show the same behavior than in the numerical results

A two-dimensional finite element model of front surface current flow in cells under non-uniform, concentrated illumination

A two-dimensional finite element model of current flow in the front surface of a PV cell is presented. In order to validate this model we perform an experimental test. Later, particular attention is paid to the effects of non-uniform illumination in the finger direction which is typical in a linear concentrator system. Fill factor, open circuit voltage and efficiency are shown to decrease with increasing degree of non-uniform illumination. It is shown that these detrimental effects can be mitigated significantly by reoptimization of the number of front surface metallization fingers to suit the degree of non-uniformity. The behavior of current flow in the front surface of a cell operating at open circuit voltage under non-uniform illumination is discussed in detail

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

Building-Integrated Photovoltaic/Thermal (BIPVT): LCA of a façade-integrated prototype and issues about human health, ecosystems, resources

Building-Integrated Photovoltaic/Thermal (BIPVT) technology offers multiple advantages; however, these types of installations include materials such as Photovoltaic (PV) cells and metals which considerably influence BIPVT environmental impact. Therefore, there is a need to evaluate BIPVT environmental profile, for instance by means of Life Cycle Assessment (LCA). In light of the issues mentioned above, the present article is an LCA study that assesses the environmental performance of a BIPVT prototype that has been developed and patented at the Ulster University (Belfast, UK). The investigation places emphasis on material manufacturing, based on Cumulative Energy Demand (CED), Global Warming Potential (GWP), ReCiPe, Ecological footprint and USEtox. The results show that according to all the adopted methods/environmental indicators and based on primary materials, the PV cells and the two vessels (steel) are the components with the three highest impacts. Scenarios which include recycling of steel, plastics and brass (landfill for the other materials has been assumed), based on CED, GWP 100a and ReCiPe endpoint, have been examined. It was found that steel recycling offers a considerable impact reduction, ranging from 47% to 85%. Furthermore, the impact of the proposed BIPVT module per m2 of thermal absorber has been calculated. The results, based on primary materials, show 4.92 GJprim/m2 and 0.34 t CO2.eq/m2 (GWP 100a). In addition, according to USEtox/ecotoxicity, USEtox/human toxicity-non-cancer (scenario based on primary materials), the PV cells present the highest contributions to the total impact of the module: 55% in terms of ecotoxicity and 86% concerning human toxicity/non-cancer. A comparison with literature is provided. Moreover, a separate section of the article is about factors which influence BIPVT environmental profile, discussing parameters such as the storage materials and the end-of-life management.The authors would like to thank “Ministerio de Economía y Competitividad” of Spain for the funding (grant reference ENE2016-81040-R)

An outdoor Test Reference Environment for double skin applications of Building Integrated PhotoVoltaic Systems

This article presents and discusses an outdoor Test Reference Environment (TRE) for double skin applications of Building Integrated PhotoVoltaic (BIPV) Systems. From the experience gained during the past 20 years in several EC research projects, an experimental tested design for a common Test Reference Environment is proposed. This outdoor test set-up allows the assessment of experimental data for electrical and thermal performance evaluation of photovoltaic systems integrated as double skin applications in the building envelope. The specific design of the Test Reference Environment makes it possible to study in a harmonised way through electrical and thermal energy flow analysis, the impact of different materials for PV modules and construction design of building envelopes. The energy balance for BIPV double skin applications is presented as well. The experimental data has been used for validation of modelling work by several academic groups which has resulted in an improved knowledge on the heat transfer, in particular the convective heat exchange coefficient for the specific double-skin boundary conditions.JRC.F.7-Renewable Energ

Solar Power Generation

Open Access journalNo abstrac

Spectral nature of soiling and its impact on multi-junction based concentrator systems

Soiling, which consists of dust, dirt and particles accumulated on the surface of conventional or concentrator photovoltaic modules, absorbs, scatters, and reflects part of the incoming sunlight. Therefore, it reduces the amount of energy converted by the semiconductor solar cells. This work focuses on the effect of soiling on the spectral performance of multi-junction (MJ) cells, widely used in concentrator photovoltaic (CPV) applications. Novel indexes, useful to quantify the spectral impact of soiling are introduced, and their meanings are discussed. The results of a one-year experimental investigation conducted in Spain are presented and are used to discuss how soiling impacts each of the subcells of a MJ cell, as well as the cell current-matching. Results show that soiling affects the current balance among the junctions, i.e. the transmittance losses have found to be around 4% higher in the top than in the middle subcell. The spectral nature of soiling has demonstrated to increase the annual spectral losses of around 2%. Ideal conditions for the mitigation of soiling are also discussed and found to be in blue-rich environments, where the higher light intensity at the shorter wavelengths can limit the impact of soiling on the overall production of the CPV system

An outdoor Test Reference Environment for double skin applications of Building Integrated PhotoVoltaic Systems

This article presents and discusses an outdoor Test Reference Environment (TRE) for double skin applications of Building Integrated PhotoVoltaic (BIPV) Systems. From the experience gained during the past 20 years in several EC research projects, an experimental tested design for a common Test Reference Environment is proposed. This outdoor test set-up allows the assessment of experimental data for electrical and thermal performance evaluation of photovoltaic systems integrated as double skin applications in the building envelope. The specific design of the Test Reference Environment makes it possible to study in a harmonised way through electrical and thermal energy flow analysis, the impact of different materials for PV modules and construction design of building envelopes. The energy balance for BIPV double skin applications is presented as well. The experimental data has been used for validation of modelling work by several academic groups which has resulted in an improved knowledge on the heat transfer, in particular the convective heat exchange coefficient for the specific double skin boundary conditions