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Various types of solar concentrators were used to increase solar cell performance and reduce the cost of the photovoltaic systems. This work aims to study the effect of optical concentrators on the solar cell performance, where two types of lenses which are linear and point focus Fresnel lenses have been used. The experimental procedure makes a Comparison between the effect of concentrated solar radiation in the ranges of (0.55-12.7 kW/m2) of these types on the solar cell parameters (output power and efficiency) for monocrystalline and polycrystalline solar cells. This procedure is done without cooling, with cooling by using heat dissipation, and with cooling by using heat dissipation with a fan. The results indicated that the output power increases about (5.3) times by using Fresnel lens concentrator without using a cooling system and (14.6) times with cooling system. Where the output power various with the range of (0.01428 - 0.3024 W) and the efficiency with the range of (2.5%.-12.1%.).

In this work,we have reported the results of our experiments,related to using the poly(vinyl alcohol) (PVA) as a matrix martial with embedding CdSe/CdS Quantumdots. The solar luminescent concentrator (LSC) is used to increase solar cell photo responsivity. The Quantum dot luminescent solar concentrator(QDLSC) are replaced on the cell’s top surface. This technique improves the efficiency of bare silicon solar cell conversion. Results showed the solar cell’s conversion efficiency has risen from 7.21% to 9.45%. This enhancement refers to the widening of the a-Si response the energy gap for CdS nanoparticles is 1.9 eV (at 622 nm).

Glass molded optics have a wide range of applications in commercial industry such as for secondary optical elements in concentrator photovoltaics (CPV), optics for light emitting diodes (LEDs), etc… In micro-CPV the reduction in size of all the components demands a very good optical quality of the primary lenses to achieve high concentrations and high efficiencies without the need of secondary optics. Glass for molding is a good candidate due to benefits such as a high abbe number, great mechanical properties, low coefficient of thermal expansion (CTE), low thermal coefficient of the refractive index (dn/dT), proven reliability, and manufacturing by a straight forward compression molding process. In collaboration with the company Holophane S.A.S. in France, several arrays of plano-convex concentrator lenses were manufactured using a manual compression mold. These first prototypes have shown absolute optical efficiency over 80% at 178X using a 1mm2 multi-junction (MJ) solar cell. Further results and potential improvements are discussed.

A cost-effective, lightweight and compact polymer solar concentrator for a CPV system based on an acylindrical lens array and a freeform waveguide was demonstrated. The optical silicone material and cyclic olefin copolymer were compared as the solar concentrator and both materials achieved ∼160x optical concentration ratio as well as ∼90% system optical efficiency. High optical efficiency and good tracking tolerance show the future viability of replacing a typical glass concentrator with a polymeric solar concentrator.

High-efficiency multijunction photoelectric converters of high-power optical emission, based on III-V materials, are presently the most promising for application in concentrator photovoltaics and radio-photonics. With increasing power of the optical emission to be converted, the influence exerted by connecting tunnel diodes on the efficiency of multijunction photoelectric converters becomes more pronounced. To provide the maximum efficiency of multijunction photoelectric converters, the connecting tunnel diodes must have a high density of the peak tunneling current, low differential resistance, and maximum optical transparency to minimize the optical loss. Efforts were made in the study to develop high-efficiency connecting p++–i–n++ tunnel diodes on the basis of GaAs/AlGaAs structures grown by molecular-beam epitaxy, with peak tunneling current of up to 200 A/cm2. These types of tunnel diodes are to be used as connecting elements in multijunction concentrator solar cells and high-power multijunction photoelectric converters based on III-V materials.

We report on six-junction inverted metamorphic (6J IMM) solar cells developed for concentrator applications. Monolithic III-V structures are grown by metal organic vapor phase epitaxy with junction bandgaps of 2.06, 1.70, 1.40, 1.16, 0.94, and 0.70 eV. The top three junctions are lattice-matched to the GaAs substrate, but the bottom three junctions use three consecutive metamorphic compositionally graded buffers to transition the lattice constant to GaxIn1-xAs compositions with the previously listed bandgaps. Performance of 6J IMM devices at one-sun AM1.5 Direct conditions gives VOC = 5.301 V, JSC = 8.05 mA/cm2, fill factor=83.9%, and efficiency=35.8%. Promising operation at high concentration is achieved but the spectrum was not controlled to AM1.5D. Tunnel junctions do not limit until at least several hundred suns. High concentration performance appears to be limited by internal heterojunction barriers created by zinc diffusion that decreases the fill factor. The properties of each junction within the 6J IMM have been separately characterized through electroluminescence and luminescent coupling measurements.

A beam down solar system is adjusted to maximize the power collected through a final optical element concentrator. The power reaching the outlet of the final optical element is studied as a function of the reflectivity of its facets, and the height of the central ray convergence point of the beam down central reflector. A configuration that maximizes the energy fed to the solar receiver during the experimental campaign of the CSPonD Demo project is chosen and implemented at the beam down installation at the Masdar Institute Solar Platform.

The numerical evaluation of a multi-channeled solar reactor coated with ZnFe2O4 film is performed by using a pore-level simulation. A ray-tracing in the concentrator allow to obtain the solar flux distribution at the aperture of the channels. Then a MC-ray tracing enable to analyze the radiative heat transfer in the porous media in order to optimize the pore-level geometry for maximum absorptance. The model considers the optical properties of ZnFe2O4 films deposited on zirconia substrate surrounded by argon, which were obtained with the characteristic matrix method. This approach allows to account for important reactor design parameters, such as ZnFe2O4 layer thickness, incoming radiation profile, diameter and length of pore.

A complete set of innovations are combined to a new heliostat of minimum cost. The main improvements are a monolithic sandwich-cantilever-arm concentrator of low material and fabrication cost, a lay down of the panels during storms to reduce the maximum wind loading of the structure, and a closed loop control to reduce the accuracy requirements on the mechanical components of the tracker. The design of the main heliostat components is described. The dimensioning of the heliostat is based on wind loads determined by wind tunnel tests. The resulting cost reduction and an outlook on possible modifications for further cost reduction is given.

In a previous work the warranty time of commercial lattice-matched GaInP/Ga(In)As/Ge triple junction concentrator solar cells was evaluated under real climatic conditions. The solar cells had a size of 7x7 mm operating with an efficiency of 35% at 820×. For these particular solar cells the warranty time for three locations, Golden (CO-USA), Madrid (Spain), and Tucson AZUSA), exhibits a 4 to 1 ratio, which affects the LCOE (Levelized Cost of Electricity) in an important way. In this work, we go a step further evaluating the influence of concentration and solar cell size on the warranty for a specific thermal design.

Demand for electrical current is very high, especially for urban areas. To meet this condition, it is considered necessary to build a system that can function effectively. Micro-scale wind turbines would be a suitable choice to provide electricity particularly in residential areas. However, the wind velocity in Indonesia that only average less than 5 m/s may prove to be an obstacle that needs to be dealt with. One concept to solve problems in areas that have low wind speed is the use of Diffuser Augmented Wind Turbine (DAWT). DAWT is the development of horizontal wind turbines that use shroud as a concentrator that can boost a low wind speed. In this study, flanges and a curved interior were added to an existing DWAT design. A CFD simulation is used to obtain the suitable shape or design of the micro-scale wind turbines. Geometry obtained by using a diffuser with curved interior diameter of 115 mm, length 230 mm, the tilt angle of 9° and flange height is 0.6 h / D. Using this geometry specification, wind velocity is increased up to 2.15 times than free stream velocity.

Off-grid solar chargers are one of the ways forward to achieve universal access to affordable, reliable, sustainable and modern electricity. To achieve this goal, the sustainability aspect of the solar chargers must be further improved. Nonimaging, static solar photovoltaic (PV) concentrators reduce the amount of PV material and thus the embodied energy and greenhouse gas emissions of the solar PV panel, improve its recyclability and reduce the use of hazardous chemicals during its manufacturing, recycling and disposal stages. A novel nonimaging solar PV concentrator named circular rotational square hyperboloid (CRSH) was recently proposed for portable solar systems for developing countries. To further reduce the material usage and production time of the concentrator while achieving an optical concentration ratio above 3× within the angles of incidence of ± 40°, the parameters of the design were optimised using genetic algorithms. The optimisation parameters are discussed and the influence of the objective function on the optimised design is presented. The genetically optimised circular rotational square hyperboloid (GOCRSH) concentrator shows an improved gain-to-volume ratio compared to the CRSH and to several nonimaging solar photovoltaic concentrators proposed for building integrated concentrated PV.

This paper summarizes the current status of the ALCHEMI project, a European collaborative undertaking under the Solar-Era.Net co-fund scheme. The project’s aim is to develop novel, low cost, HCPV modules that operate at ∼1000 suns, and demonstrate a DC module efficiency of >37% under Concentrator Standard Test Conditions (CSTC), and a manufacturing process that will achieve costs

Concentrator Photovoltaic-Thermoelectric (CPV-TE) hybrid devices have the potential to address areas of limitation within concentrator photovoltaic devices, using the inherent flexibility and controllability of thermoelectrics. In this work, a full CPV-TE module was designed and fabricated using commercial Primary and Secondary Optical Elements (POEs and SOEs respectively). The SOE-CPV-TE hybrid receivers were characterized prior to integration within the module, and connected into a string of three receivers. The acceptance angle of the POE-SOE-CPV-TE hybrid module was experimentally characterized, and outdoor on-tracker data was obtained at the University of Jaen. For the first time, the performance of CPV-TE hybrid devices was evaluated within a 3-receiver string, and the efficiency of on-sun TE cooling was investigated.A preliminary break-even point was found at 0.3A, for active cooling verses non- cooling for the CPV-TE hybrid receivers. This highlights the future on-sun performance increases possible with further optimised CPV-TE module designs, including a low-power regime for optimised TE operation.

This paper investigates the outdoor performance of a new kind of hybrid concentrator photovoltaic module. The concept which we name, EyeCon, uses an array of Fresnel lenses to concentrate direct irradiance onto III-V four-junction solar cells while a large-area silicon cell absorbs diffuse sunlight and also acts as a heat distributing substrate. The preliminary results show that under a high ratio of direct to global irradiance (> 0.9) the concept is capable to convert up to 36.8 % of the global solar resource rather than just the direct beam. Moreover at a low ratio of direct to global irradiance (0.57) the hybrid module generates 30 % additional power with respect to the array of concentrator four-junction solar cells alone. The Eyecon module is applicable to all regions of the world and allows reaching the highest energy yield per module area of any PV technology.This paper investigates the outdoor performance of a new kind of hybrid concentrator photovoltaic module. The concept which we name, EyeCon, uses an array of Fresnel lenses to concentrate direct irradiance onto III-V four-junction solar cells while a large-area silicon cell absorbs diffuse sunlight and also acts as a heat distributing substrate. The preliminary results show that under a high ratio of direct to global irradiance (> 0.9) the concept is capable to convert up to 36.8 % of the global solar resource rather than just the direct beam. Moreover at a low ratio of direct to global irradiance (0.57) the hybrid module generates 30 % additional power with respect to the array of concentrator four-junction solar cells alone. The Eyecon module is applicable to all regions of the world and allows reaching the highest energy yield per module area of any PV technology.

The competitive landscape for solar power has changed dramatically over the last few years with 100’s of GW’s deployed and system costs dropping rapidly to approximately US$1.20-1.50/W for PV and US$2-4/W for CSP. While concentrator PV systems have demonstrated an efficiency of double that of PV and shown excellent reliability, to date the relatively high installed cost per m2 has limited deployment of these systems. The authors have unpacked the cost stack, to determine the underlying cost drivers and consequently have devised a product architecture and business model which address the key issues necessary to provide a pathway to effective low cost solar energy. This strategy is currently being demonstrated through the sale, manufacture and deployment of the ”PV Ultra” product according to the new paradigm. A “central receiver-PV” architecture called PV Ultra has been devised by RayGen, with 1MW built and validated. These features define a competitive solar energy product which has an attractive ROI even at 1MW.

Three dimensional secondary concentrators are exposed to high radiation fluxes, part of which is absorbed by the reflecting material, leading to elevated wall temperatures which may cause reflectance degradation and mechanical distortion. Temperature monitoring and thermal management is required. Existing 3D secondary concentrators used in beam-up or beam-down tower plants use water-based convective cooling for which failures and leaks have been reported. The present work tested two alternative non-liquid-based cooling strategies: enhanced radiative cooling using a high-emissivity paint and forced-air convective cooling. The concentrator under no cooling enhancement reached temperatures above the acceptable limit, indicating the need for better cooling. Forced-convective cooling had the most noticeable effect and proved sufficient for the considered testing conditions. The impact of radiative cooling enhancement was lower in the considered incident flux conditions, as the initial temperature without enhan...

Single junction concentrator solar cells operate at efficiencies that are surprisingly close to their one-sun equivalents cells; for the case of GaAs the 1-sun efficiency record stands at 28.8% while under concentration it stands at 29.3%. This arises due to three effects: Firstly the AM1.5G spectrum has a stronger blue component than the AM1.5D low-AOD concentrator spectrum and hence yields higher efficiency from higher band-gap cells. Secondly the 1-sun GaAs device achieves an approximate 2% absolute efficiency increase due to the removal of the substrate; a feature that is absent from the concentrator cell. Thirdly, the difficulty of achieving front metal grid structures that are sufficiently conductive to enable peak efficiencies at several hundred suns frustrates the achievable efficiency of a GaAs solar cell.Single junction concentrator solar cells operate at efficiencies that are surprisingly close to their one-sun equivalents cells; for the case of GaAs the 1-sun efficiency record stands at 28.8% while under concentration it stands at 29.3%. This arises due to three effects: Firstly the AM1.5G spectrum has a stronger blue component than the AM1.5D low-AOD concentrator spectrum and hence yields higher efficiency from higher band-gap cells. Secondly the 1-sun GaAs device achieves an approximate 2% absolute efficiency increase due to the removal of the substrate; a feature that is absent from the concentrator cell. Thirdly, the difficulty of achieving front metal grid structures that are sufficiently conductive to enable peak efficiencies at several hundred suns frustrates the achievable efficiency of a GaAs solar cell.

Obtaining low front contact resistances in inverted metamorphic multijunction (IMM) solar cell is essential for reducing resistance losses at high concentration. However, these devices present some particularities which make this issue specially challenging. On one hand, the solar cell fabrication requires a flip-chip process in order to transfer the semiconductor structure to a handling substrate. This implies that the front contact deposition must not compromise the integrity of the bonding material, which is usually temperature sensitive. On the other hand, the heavily doped front contact layer is grown firstly, therefore is subjected to an important thermal load caused by the epitaxy growth, which is suspected to damage its electronic properties. In this work, the specific front contact of several solar cells, grown in inverted and non- inverted configurations and deposited by electroplating and evaporation, is studied. In addition, we present a low temperature annealing for an evaporated Pd/Ge/Ti metal system on n-GaAs which achieves very low resistance values ρc ≈ 10-7 Ω·cm2 in all inverted solar cells tested regardless of the thermal load applied to the front contact layer.

A photovoltaic (PV) and thermoelectric (TE) hybrid module was developed for application to high concentration solar systems. The waste heat from the solar cells under concentrated light illumination was utilized to generate additional electricity by assembling TE devices below the multi-junction solar cells (MJSCs). Considering the high operating temperature of the PV and TE hybrid module compared with conventional concentrator PV modules, the TE device could compensate a part of the MJSC efficiency degradation at high temperature. The performance investigation clarified the feasibility of the hybrid PV and TE module under highly concentrated sunlight illumination.

Series-connected five (5J) and six junction (6J) concentrator solar cell strategies have the realistic potential to exceed 50% efficiency to enable low-cost CPV systems. We propose three strategies for developing a practical 6J device. We have overcome many of the challenges required to build such concentrator solar cell devices: We have developed 2.1 eV AlGaInP, 1.7 eV AlGaAs, and 1.7 eV GaInAsP junctions with external radiative efficiency greater than 0.1%. We have developed a transparent tunnel junction that absorbs minimal light intended for the second junction yet resists degradation under thermal load. We have developed metamorphic grades from the GaAs to the InP lattice constant that are transparent to sub-GaAs bandgap light. We have grown and compared low bandgap junctions (0.7eV – 1.2 eV) using metamorphic GaInAs, metamorphic GaInAsP, and GaInAsP lattice-matched to InP. And finally, we have demonstrated excellent performance in a high voltage, low current 4 junction inverted metamorphic device us...

HCPV uses trackers, but their cost and reliability have raised problems. These problems may be solved by substantially increasing acceptance angle and mechanical tolerance. For a demonstration of the possibility of such substantial improvement, a 30 minutes intermittent tracking in high concentration applications was examined. To allow for 30 minutes intermittent tracking, both advanced optics and an advanced tracking control were investigated. For advanced optics, a 100 x refractive and dielectric concentrator was designed. It had about plus or minus 5° of acceptance angle. For advanced tracking control, a feed-forward control with a linear error correction was investigated. With combining both optimizations, it was shown that 30 minutes intermittent tracking was validated in outdoor experiments even for an as high as 100 x concentration.

We estimated the annual mean conversion efficiency of partially static concentrator (PSC) module. The PSC module consistes of static concentrator, small III-V top solar cell and large Si bottom solar cell. The large Si bottom solar cell absorbes the solar power that is not collected by the III-V top soler cell. The mean optical efficiency decreased with the increase of concentration ratio. The decreasing ratio of mean optical efficiency between 1X to 4X was 49.9%. By using PSC module structure, it was possible to boost the annually mean conversion efficiency. The decreasing ratio of annually mean conversion efficiency between 1X to 4X was 21.5%. The acceptance angle of conversion efficiency was larger than that of optical efficiency. The PSC module structure also improved acceptance angle of the conversion efficiency.

Concentrating sunlight and focusing on smaller solar cells increases the power output per unit solar cell area. In the present study, we highlight the design of a low concentrating photovoltaic (LCPV) system and its performance in different test conditions. The system essentially consists of a reflective type 3.6× cross compound parabolic concentrator (CCPC) designed for an acceptance angle of ± 30°, coupled with square shaped laser grooved buried contact (LGBC) silicon solar cells. A heat exchanger is also integrated with the PV system which extracts the thermal energy rejected by the solar cells whilst maintaining its temperature. Indoor characterization is carried out to evaluate the system performance under standard conditions. Results showed a power ratio of 3.12 and an optical efficiency of 73%. The system is placed under outdoor environment on a south facing roof at Penryn, UK with a fixed angular tilt of 50°. The high angular acceptance of the system allows collection of sunlight over a wider range. Results under different climatic conditions are presented and compared with a non-concentrating system under similar conditions. On an average, the LCPV system was found to collect an average of 2.54 times more solar energy than a system without the concentrator.

In this work, the possibility of solar tiles structures development on the basis of stationary cylindrical parabolic concentrators and planar-type or multi-junction silicon solar cell has been studied. The designed structure has been analyzed and the characteristics of samples have been investigated for various application conditions. The outer dimensions, shape and weight correspond to those of conventional tiles. The calculated value of concentration ratio is 4.96 while its factually achieved value is 4. The effective aperture angle is in the range of 26.1° to 36°. The voltage in the maximum output power mode is 1V to 1.2V, for planar-type solar cells, and 2V to 3.2V, for multi-junction ones. The output power for experimental samples in standard test conditions (STC) is 8W, 10W, 16W, 20W and 24W depending on actual parameters of solar radiation receiver and optical deflector.

The solar tower concentrator is mainly composed of the central receiver on the tower top and the heliostat field around the tower. The optical efficiencies of a solar tower concentrator are important to the whole thermal performance of the solar tower collector, and the aperture plane of a cavity receiver or the (inner or external) absorbing surface of any central receiver is a key interface of energy flux. So it is necessary to simulate and analyze the concentrated time-changing solar flux density distributions on the flat or curved receiving surface of the collector, with main optical errors considered. The transient concentrated solar flux on the receiving surface is the superimposition of the flux density distributions of all the normal working heliostats in the field. In this paper, we will mainly introduce a new backward ray tracing (BRT) method combined with the lumped effective solar cone, to simulate the flux density map on the receiving-surface. For BRT, bundles of rays are launched at the recei...

The optical and thermal efficiency of parabolic trough collector solar fields is dependent on the performance and assembly accuracy of its components such as the concentrator and absorber. For the purpose of optical inspection/approval, yield analysis, localization of low performing areas, and optimization of the solar field, it is essential to create a complete view of the optical properties of the field. Existing optical measurement tools are based on ground based cameras, facing restriction concerning speed, volume and automation. QFly is an airborne qualification system which provides holistic and accurate information on geometrical, optical, and thermal properties of the entire solar field. It consists of an unmanned aerial vehicle, cameras and related software for flight path planning, data acquisition and evaluation. This article presents recent advances of the QFly measurement system and proposes a methodology on holistic qualification of the complete solar field with minimum impact on plant Operation.

A stochastic multi-objective optimisation method is used to determine receiver geometries with maximum second law efficiency, minimal average temperature and minimal surface area. The method is able to identify a set of Pareto optimal candidates that show advantageous geometrical features, mainly in being able to maximise the intercepted flux within the geometrical boundaries set. Receivers with first law thermal efficiencies ranging from 87% to 91% are also evaluated using the second law of thermodynamics and found to have similar efficiencies of over 60%, highlighting the influence that the geometry can play in the maximisation of the work output of receivers by influencing the distribution of the flux from the concentrator.

We propose a theoretical framework for analyzing the energy yields of partial concentrators. A partial concentrator uses a concentrator cell to absorb the principal defracted or reflected light rays from its concentrator optics and a backplane cell to absorbs the diffused or defocused light. This concept can be applied to the concentrator system when accurate sun-tracking is not available, such as on a vehicle. This analysis framework provides a simplified way to describe the uncertainties of solar incidences dealt by partial concentrator. This help identified a clearer design criteria of partial concentrator in order to outperform the flat-panel PV or conventional CPV.

III-V on Si cell is one of the most promising candidates of the low-cost and high-efficiency solar cell beyond the limit of Si cells. However, it is likely that the cost of III-V cell will keep greater than that of Si cells. The partial concentrator technology was invented to concentrate the sunlight onto smaller III-V cells on the Si cell with the increased acceptance angle for static concentrator operation. The partial concentrator allows on-axis optical loss but expands the apparent acceptance angle often beyond the thermodynamic limit. The spilled light will be saved and collected by the bottom Si cell. It is not just placing the Si cell around the concentrated III-V cell, but its design philosophy is “partially” collecting the sunlight to the III-V cell to expand the acceptance. Depending on the values of cost parameters, the cost of the partial CPV module becomes minimum at 4 x – 10 x of concentration onto the top III-V cell, meaning that the area of expensive III-V cell can be saved to 1/4 – 1/10. ...

The sun provides the earth with huge amounts of energy that can be exploited in various forms. Its exploitation can be done by using a parabolic through solar concentrator integrated with thermal storage tank, that we already made, and it is our main study. This study obviously requires special attention to the effect of the parameters of the fluids, in addition to thermal performances of this system. To do this, we studied the thermal behavior of this concentrator, and by choosing the summer period because of its stable illumination (clear sky). Before starting the test, it is necessary to check the flow circuit and the storage tank which completely filled with fluid, started the measures on the morning, the concentrator directed towards the sun until the sunset, we recorded the variation of different temperatures such as Tin, Tout, Tsur, Tfluid and Tamb.We have compared the evaluation of temperatures between water and thermal oil in order to determine the best thermal behavior and the importance of the ...

The work presents an experimental techniques aimed at investigating the subcells photocurrent nonlinear behavior in MJ SC with irradiance increase and the revealing of a possible shift in the current matching between the subcells of the MJ SC at sunlight concentration ratio rise and determining the causes of possible current mismatch.

We present an all-laser micro-machined superhydrophobic/hydrophilic structure for a targeted pre- concentration of analyte molecules from an deposited water drop. The design of the evaporating concentrator combines the superhydrophylic Au-coated central pillar surrounded by the high-aspect-ratio microstructures having hierarchical micro/nano roughness both fabricated in a bulk polytetrafluoroethylene substrate using by a direct micro-machining with a femtosecond-pulse filament. The surrounding high-aspect-ratio textures posseses a high contact angle exceeding 170° and hysteresis less than 1.5° for the deposited 3-μl. water drop providing controllable pre-concentration of the analyte from the evaporating drop within a small superhydrophylic area of about 80×80 µm2 and resulting in the increase of the initial analyte concentration by 104 times.

On the example of the HelioTrough® collector development the full accompanying and supporting qualification program for large-scale parabolic trough collectors for solar thermal power plants is described from prototype to demonstration loop scale. In the evaluation process the actual state and the optimization potential are assessed. This includes the optical and geometrical performance determined by concentrator shape, deformation, assembly quality and local intercept factor values. Furthermore, its mechanical performance in terms of tracking accuracy and torsional stiffness and its thermal system performance on the basis of the overall thermal output and heat loss are evaluated. Demonstration loop tests deliver results of collector modules statistical slope deviation of 1.9 to 2.6 mrad, intercept factor above 98%, peak optical performance of 81.6% and heat loss coefficients from field tests. The benefit of such a closely monitored development lies in prompt feedback on strengths, weaknesses and potentia...

An optimized and low cost linear Fresnel collector, adapted to the West Africa context, is being designed using local mankind and locally available materials. There is an already built collector. The concentrator has 7.5 m2 of mirrors segmented in equal width of 0.1 m. The receiver has a trapezoidal cavity with seven copper absorber tubes. The sun tracking system operates in open loop and the sun position is calculated using an algorithm. The components of the collector were selected purposely to reduce production cost while optimizing its performances. The cost of collector is €275 / m2 of mirrors and €255 / kWth for solar field and receiver respectively. The material and method for the collector characterization are outlined. An organic Rankine cycle will be coupled with the collector for electricity generation. Dynamic modelling, of an organic Rankine cycle, is being investigated using Gibbs equivalents systems method.

Linear Fresnel Reflector concentrators (LFR) are a potential solution for low-cost electricity production. Nevertheless in order to become more competitive with other CSP (Concentrated Solar Power) technologies, in particular with the Parabolic Trough concentrator, their overall solar to electricity efficiencies must increase. A possible path to achieve this goal is to increase the concentration factor, hence increasing the working temperatures for higher thermodynamic efficiency (more energy collection) and decrease the total number of rows of the solar field (less parasitic losses and corresponding cost reduction). This paper presents a dual asymmetric CEC-type (Compound Elliptical Concentrator) LFR (Linear Fresnel Concentrator) for evacuated tubular receivers. The concentrator is designed for a high concentration factor, presenting an asymmetric configuration enabling a very compact solution. The CEC-type secondary mirror is introduced to accommodate very high concentration values with a wide enough acceptance-angle (augmenting optical tolerances) for simple mechanical tracking solutions, achieving a higher CAP (Concentration Acceptance Product) in comparison with conventional LFR solutions. The paper presents an optical and thermal analysis of the concentrator using two different locations, Faro (Portugal) and Hurghada (Egypt).

Low tracking accuracy of tracker, wind induced vibration of structure and lens deformation by temperature lead to non-vertical incident irradiation to the Fresnel lens, which necessitates a secondary concentrator in actual engineering application of concentrating photovoltaic module. This paper adds a secondary focusable microprism between Fresnel lens and solar cells in order to improve optical efficiency. The 3D model of microprism is established by SOLIDWORDS and main parameters are optimized using ZEMAX. Results show that combination of Fresnel lens and focusable microprism achieves a higher energy when the secondary microprism upper spherical diameter is 18mm, the opposite side face included angle is 116°, and the side length of the bottom is 2.15mm. The highest energy of solar cell surface can reach 2.4998W, improving 33.2%, and the module height with the secondary microprism is 88mm, which reduces by 5.5mm without secondary microprism. Experimental results show that the optical efficiency of 400X c...

In this work, we investigated the impact of intensive heat loads on concentrator solar cells assemblies. As test samples, we employed lattice-matched and lattice-mismatched triple-junction solar cells made of GaInP/GaInAs/Ge. The thermal loads were induced by different manners. We used drying cabinets, external power supplies, and a combination of both to achieve maximum test temperatures of 180 °C. For the performance analysis, we utilized flash light solar simulators and an electroluminescence (EL) imaging tool. Our experiments revealed a significant difference depending on the applied manner of heating. The highest impact was observed for the pure heat treatment in drying cabinets. This was particularly visible in the spatial EL images, but also in the IV curves. In contrast, running the concentrator solar cells as forward-biased diodes using an external current supply of 2000 mA, which corresponds to 2000 suns, did not lead to any significant changes in EL and IV curves. However, deformation of the fr...

This paper presents the design, manufacture and electrical characterization of novel hybrid III:V Concentrator Photovoltaic-Thermoelectric receivers. Addition of an encapsulating and spectral homogenizing single active surface secondary optic lens increased the solar cell electrical power output from 7.66mW (ALPHA no cooling) to 18.20mW (KAPPA with TE cooling). The effective optical concentration of the optics, based on short circuit current, was x2.4. A linear irradiance vs maximum power receiver output relationship was observed (R2=0.9978), confirming good optical alignment during manufacture and likewise internal current matching of the series-connected triple-junction cell. An in-depth COMSOL model for simulated evaluation of the synergistic thermally-dependent parameters inherent to hybrid devices was built and experimentally validated.

Ultrahigh concentrator photovoltaics hold a great potential in both reducing the cost of photovoltaic energy and to higher conversion efficiencies. The challenges in their design and manufacturing however have not yet permitted a reliable ultrahigh (>2000X) system. Here we propose an ultrahigh concentrator photovoltaic design 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 to accept light from four different directions and focus the light towards the solar cell. The extremely high geometrical concentration of 5800X was chosen in anticipation of the losses accompanied with ultrahigh concentration due to alignment difficulties. The system was designed with manufacturability as one of the priorities and resulted in easily achieving >2000X concentration for a first prototype with non-achromatic Fresnel lenses and in house secondarys. Higher concentrations are anticipated for future prototypes but i...