Concentrator Photovoltaic Module Research Articles

Influence of Heat Dissipation Conditions on the Characteristics of Concentrator Photoelectric Modules

The results of studying the effect of various conditions of heat dissipation on heating and temperature distribution in components of concentrator photovoltaic modules are reported. The modules based on Fresnel lenses and triple-junction solar cells InGaP/GaAs/Ge mounted on copper and steel heat sinks are studied. In order to determine the thermal characteristics, we use a method, which makes it possible to measure the temperature of the p–n junctions in the solar cells under laboratory conditions upon the simulation of thermal processes arising in the course of operation of the module under typical conditions. Further, the above temperature is used to calculate the value of the thermal resistance for a system consisting of a solar cell and the surrounding medium. The thermal processes in the module are simulated by transferring current through the solar cells in the forward-bias direction. The value of heating of the solar cells is determined by comparing the forward-voltage drops measured at the time of its rapid application or switching-off under various conditions of heat removal. The conditions of heat removal are varied using the generator’s air flow.

Влияние условий теплоотвода на характеристики концентраторных фотоэлектрических модулей

AbstractThe results of studying the effect of various conditions of heat dissipation on heating and temperature distribution in components of concentrator photovoltaic modules are reported. The modules based on Fresnel lenses and triple-junction solar cells InGaP/GaAs/Ge mounted on copper and steel heat sinks are studied. In order to determine the thermal characteristics, we use a method, which makes it possible to measure the temperature of the p–n junctions in the solar cells under laboratory conditions upon the simulation of thermal processes arising in the course of operation of the module under typical conditions. Further, the above temperature is used to calculate the value of the thermal resistance for a system consisting of a solar cell and the surrounding medium. The thermal processes in the module are simulated by transferring current through the solar cells in the forward-bias direction. The value of heating of the solar cells is determined by comparing the forward-voltage drops measured at the time of its rapid application or switching-off under various conditions of heat removal. The conditions of heat removal are varied using the generator’s air flow.

Comparative analysis of parameter extraction techniques for the electrical characterization of multi-junction CPV and m-Si technologies

Modelling the current-voltage (I-V) characteristics of photovoltaic (PV) modules under real operating conditions is crucial for the better understanding of each technology. The most commonly used model for the electrical characterization of PV is the single-diode model where the five parameters are extracted through a variety of techniques. Although numerous extraction methods were developed for conventional PV technologies, the studies concerning the concentrating photovoltaic (CPV) technology are still limited. In this work, three analytical parameter extraction methods (Phang et al., Blas et al. and Khan et al.) are applied and compared for a multi-junction (MJ) CPV and a monocrystalline (m-Si) module based on long-term outdoor measurements in Jaén, Spain. The sensitivity of the models against the dominant parameters that influence the behaviour of PV and CPV (i.e. irradiance, module temperature and air mass) is also investigated. Furthermore, the effect of irradiance on the extracted parameters is discussed including the derivation of the corresponding fitting equations and errors. The results indicate that the most robust method is the one proposed by Phang et al. for the CPV module (normalised root mean square error, NRMSE, of 1.55%) and the one proposed by Blas et al. for the m-Si module (NRMSE of 0.58%). The method of Khan et al. resulted the highest error values for every case (NRMSE of 4.5% and 1.74% for CPV and m-Si respectively) while the Phang et al. method exhibited a similar error for both technologies. The main outcome of this work contributes to the optimum selection of parameter extraction techniques depending on the technology and the desired associated errors while the analysis of the dependence of the parameters on irradiance provides a better understanding of each technology’s behaviour in the field.

Measured Efficiency of a Luminescent Solar Concentrator PV Module Called Leaf Roof

A functional prototype of a luminescent solar concentrator photovoltaic (LSC PV) module, called Leaf Roof, aims at demonstrating the design features of LSC PV technologies such as coloring, transparency, and flexibility in physical shape. In this paper, the prototype is presented and the first measurements of its performance are shown. The geometrical gain of this new type of PV module is 3.6. For two types of Leaf Roof modules, I – V curves have been measured resulting in efficiencies of 5.8% for a red-colored PV module, and 5.5% for a green-colored PV module under similar conditions. These results demonstrate colorful, robust solar energy collectors which can be produced in a wide variety of shapes are viable, attractive devices for use in building integrated systems. Additionally, thanks to the use of poly(methyl methacrylate) (PMMA) as a cell encapsulant, the Leaf Roof modules are less susceptible to energy losses at elevated temperatures due to high irradiance and high ambient temperature conditions.

Thermal management approaches of Cu(Inx,Ga1−x)Se2 micro-solar cells

Concentrator photovoltaics (CPV) is a cost-effective method for generating electricity in regions that have a large fraction of direct solar radiation. With the help of lenses, sunlight is concentrated onto miniature, highly efficient multi-junction solar cells with a photovoltaic performance above 40%. To ensure illumination with direct radiation, CPV modules must be installed on trackers to follow the sun’s path. However, the costs of huge concentration optics and the photovoltaic technology used, narrow the market possibilities for CPV technology. Efforts to reduce these costs are being undertaken by the promotion of Cu(Inx,Ga1−x)Se2 solar cells to take over the high cost multi-junction solar cells and implementing more compact devices by minimization of solar cell area. Micrometer-sized absorbers have the potential of low cost, high efficiencies and good thermal dissipation under concentrated illumination. Heat dissipation at low (<10×) to medium (10 × to 100×) flux density distributions is the key point of high concentration studies for macro- and micro-sized solar cells (from 1 µm2 to 1 mm2). To study this thermal process and to optimize it, critical parameters must be taken in account: absorber area, substrate area and thickness, structure design, heat transfer mechanism, concentration factor and illumination profile. A close study on them will be carried out to determine the best structure to enhance and reach the highest possible thermal management pointing to an efficiency improvement.

Experimental analysis and simulation of a production line for CPV modules: impact of defects, misalignments, and binning of receivers

AbstractAn inherent characteristic of high concentrator photovoltaics (HCPV) modules is a tight mechanical tolerance caused by the narrow angular transmission of the optical system, typically below or close to 1°. Misalignments in the modules caused during the assembly process in the production line will degrade not only the electrical but also the angular performance of the module. Moreover, dispersion in the electrical characteristics of the elementary units comprising a module would lead also to power loss. Quality control and data analysis on the production line is of great significance for adjusting the production line and preserving the angular tolerance and the electrical performance. This is particularly critical during the set‐up and tuning of an automated production line. This paper presents the results of a pilot production line for HCPV modules carried out within the European funded ECOSOLE project. Several quality controls were established, which are the binning of the photovoltaic receivers, the measurement of misalignments among the elementary units within every module, and the indoor electrical characterization of the modules. Collected experimental data during the tuning phase of the pilot line were used to validate a module performance model based on production parameters. Monte Carlo method is lately applied to the model to assess the influence of production defects of diverse nature and the adequacy of quality controls, in several manufacturing scenarios beyond the specific constrains of the ECOSOLE experience.

Optimising thermal photovoltaic energy system for green and sustainable energy generation

Electricity generated from a concentrated thermal photovoltaic system can be improved upon for optimum output. This investigation considered the various options of optimising system operation via effective control of the operating conditions. It examined various options of varying the system configurations for optimised system efficiency and power output and at minimum operating costs. The number of mirrors and photovoltaic cells for use in the concentrated thermal photovoltaic system were set at eight as standard for the system operation. This number was varied down and up (from eight to six and then from eight to ten) to study the effects of these variations on the concentrated thermal photovoltaic system efficiency and generated power output. A novel thermal model was built in two dimensions and was used to simulate the thermal performance of the concentrated thermal photovoltaic modules. The parameters used for the materials involved were defined and the appropriate physics applied in the study of various operating conditions that affected the system performance for the two-dimensional system were stated. The results showed that temperature rise was least in the ten mirrors configuration and highest in the six mirrors configuration. The six PV cells-mirrors configuration, however, generated the highest power output of the three different configurations considered. The six PV cells/mirrors configuration utilised the least numbers of mirrors and PV cells out of the three configurations, ultimately translating to reduced-materials cost for the operation. Based on these findings, the choice of the lower number of six mirrors and six PV cells was considered the most economical and, therefore, most desirable.

Optical Design and Validation of an Infrared Transmissive Spectrum Splitting Concentrator Photovoltaic Module

A new modular, hybrid solar power system is designed to generate both electrical and thermal energy by utilizing the full solar spectrum. The key element, an infrared-transparent concentrator photovoltaic (CPV) module, acts as a spectrum splitter, dividing solar radiation into two parts. The ultraviolet and visible light (“in-band”) are converted to electricity with high efficiency in CPV cells, while the infrared light (“out-of-band”) is transmitted directly to a thermal receiver, where thermal power may be converted to electricity by a suitable heat engine or used directly for industrial process heat applications whenever needed. Here, we describe the optical design, modeling, fabrication, and performance validation of this novel spectrum splitting CPV module. A transfer matrix style approach, cumulative transmission model, is built to study the reflection, absorption, and transmission in each layer of the CPV module. To optimize the optical performance, different materials for module superstrate/substrate, encapsulant, cell substrate, and cooling fluids are compared in order to enhance the transmission of out-of-band light through the CPV module by minimizing absorption. Six antireflection coatings along with front and backside electrical contact grids are designed to maximize transmittance of in-band light to the cell and out-of-band light to the thermal receiver. The final design, currently being prototyped, predicts out-of-band light transmission to the thermal receiver of 74.1% (for the passively cooled version) and 65.3% (for the actively cooled version). When epitaxial liftoff technology is applied, the transmission will change to 80.8% (passively cooled) and 71.9% (actively cooled). Experimental prototypes show good agreement with modeled optical performance.

111 sun concentrator photovoltaic module with wide acceptance angle that can efficiently operate using 30-min intermittent tracking system

In this study, we propose a new concentrator photovoltaic (CPV) system design with a large-acceptance-angle lens, which tracks the sun on the basis of a new 30-min intermittent tracking method that does not require a special high-precision CPV tracking system. This will reduce costs, because a large percentage of the cost of a typical CPV system comes from the expensive accurate tracking system. The present system had a concentration ratio of 111 and an acceptance angle of 4.5°. We conducted an experiment to evaluate the thermal and electrical performances of the system in an outdoor test site in Miyazaki, Japan. The experimental results were compared with optical, thermal, and electrical simulation results. The simulated results showed good agreement with the experimental ones.

Proof-of-concept of a building-integrated hybrid concentrator photovoltaics-lighting system

A hybrid concentrator photovoltaics (CPV) module that combines the production of electricity and transports sunlight is proposed as a means to reduce the energy needs of buildings by two complementary solar energy approaches. Both concepts share the need for a solar tracker and an infrastructure to concentrate the sunlight which allows a reduction in costs of the proposed system. The CPV part is a well-known technology to produce electricity that serves as a host for the light subpart that transports sunlight through optical fibres. Measurements of a proof-of-concept show that in nominal conditions the lighting subpart is more efficient in the task of transporting sunlight than converting sunlight to electricity and then to light again. The efficiency threshold is a direct function of the fibre material and distance transported and the generated light is very similar to the solar light in terms of spectral content. Based on PMMA optical fibres and conventional CPV technology, the hybrid module converts 28.7% of the sunlight into electricity. Regarding the light transported by the optical fibres they slightly shift sunlight to bluish white but the quality of light is still comparable to a typical fluorescent lamp used in offices.

Reconfiguration of 25 kW Solar PV Power Plant

Power is one of the most critical components of infrastructure resolvent for the economic growth and welfare of nations. The development of sufficient infrastructure is essential for sustained growth of the Indian economy. . Electricity demand in the country has increased rapidly due to the fast growing industries and population growth. Solar play major role to meet the increasing demand. A 25 kW grid-connected photovoltaic (PV) power generation system was installed and monitored at the Kamaraj College of Engineering and Technology in Virudhunagar since March 2014. In this project work the various factors that affect the performance of the solar PV are analyzed. The solar PV panels installed here are mono crystalline, poly crystalline and low concentrated PV modules. Each PV panels are connected in series or parallel. In this PV plant several modules are get damaged due to the abnormal weather condition and some panels are in good working condition. The only solution of this problem is the rearrangement of solar PV panels. By doing reconfiguration, the performance of the solar plant should be improved and also it improves the reliability and reduces the vulnerability to power loss by damage.

Current-voltage dynamics of multi-junction CPV modules under different irradiance levels

Abstract The current-voltage output of concentrator photovoltaic (CPV) modules shows a complex behaviour under irradiance variations due to the use of multi-junction solar cells and optical elements. The single exponential model (SEM) relates the I-V curve of a PV device and its five characteristic parameters. Hence, it is fundamental to understand the dependence of the SEM model and I-V parameters of CPV modules with irradiance. In this paper, two samples of concentrator modules were characterized under fully controlled conditions by using a CPV solar simulator for light intensities within 700–1000 W/m 2 . Results show that the photo-generated current increases linearly with irradiance, the diode ideality factor and saturation current present a stable behaviour under irradiance variations while the parasitic resistances, i.e. series and shunt, trend to decrease as the intensity increases. In addition, different approximations are carried out in the SEM model equation to explain the dependence of the performance of the concentrators with light intensity. Finally, the prediction of the I-V curves and key electrical parameters from reference values is discussed. Results show a good fitting of the I-V curves until 750 W/m 2 and a high accuracy in the estimations of the electrical parameters with a MAPE lower than 1.2%, a MRE within 1% and a R 2 equal of higher than 0.9.

The optical design and performance of a concentrator photovoltaic module

Concentration photovoltaic (CPV) modules promise a more efficient, higher power output than traditional photovoltaic modules. This is achieved by concentrating sunlight onto a small 1 cm2 concentrator triple-junction (CTJ) InGaP/InGaAs/Ge cell by using high quality precision optics. In order to achieve high energy performance and reliability, well thought-out design decisions must be made in the development of a CPV module. This paper investigates the design of two CPV modules (Module I and II), which are based on the Sandia III Baseline Fresnel module. The investigation concentrated on the effect of the optimization of the optical design on the electrical performance characteristics of CTJ cells with good thermal dissipation. The best performance achieved by Module I was at 336 times operational concentration (Xo), which produced a Pmax of 10.29 W per cell, with cell and module efficiencies of 39% and 24%, respectively. In the development of the second module (Module II) pre-deployment criteria such as the CTJ cell and system components characteristics was used to eliminate faulty components from the system what was observed in Module I. Cell units that were optimized in Module II showed no form of degradation in their Current-Voltage (I-V) characteristics. The cell unit operating under optical misalignment showed a progressive degradation with long term operation in the field.

Rectifying structural deflection effect of large solar concentrator via correction of sun-tracking angle in the concentrator photovoltaic system

The influence of self-weight structural deflection of large solar concentrator has caused significant impact to the quality of concentrated solar flux. The resulted negative outcomes from structural deflection, including image distortion and pointing error, can deteriorate the electrical power generated by dense-array concentrator photovoltaic (CPV) module located at the target of large solar concentrator. In this article, a novel corrective measure for sun-tracking angle is proposed to rectify the structural deflection effect on the large solar concentrator and hence to optimize the electrical output power of dense-array CPV module. The methodology of the proposed corrective measure has been formulated and discussed in details using numerical simulation via ray-tracing technique. The simulated result has shown that the proposed method is proficient to recover the deviated and distorted solar flux distribution in the receiver without affecting the maximum solar concentration ratio and hence to reduce the electrical power loss. For the overall gain, the maximum output power has been increased from 3562W to 4030W and the electrical power loss has been reduced from 12.4% to 0.8% at elevation angle of 60° in the dense-array CPV system.

An end of service life assessment of PMMA lenses from veteran concentrator photovoltaic systems

The optical performance of poly(methyl methacrylate) lenses from veteran concentrator photovoltaic modules was examined after the end of their service life. Lenses from the Martin-Marietta and Intersol module designs were examined from the “Solar Village” site near Riyadh, Saudi Arabia, as well as the Phoenix Sky Harbor airport, followed by the Arizona Public Service Solar Test and Research (APS-STaR) center in Tempe, Arizona. The various lens specimens were deployed for 20, 27, and 22 years, respectively. Optical characterizations included lens efficiency (Solar Simulator instrument), material transmittance and haze (of coupons cut from veteran lenses, then measured again after their faceted back surface was polished, and then measured again after the incident front surface was polished), and direct transmittance (as a function of detector's acceptance angle, using the Very Low Angular Beam Spread (“VLABS”) instrument). Lens efficiency measurements compared the central region to the entire lens, also using hot and cold mirror measurements to diagnose differences in performance. A series of subsequent characterizations was performed because a decrease in performance of greater than 10% was observed for some of the veteran lenses. The optimal focal distance of the lenses was quantified using the Solar Simulator, and then correlated to lens curvature using a recently developed measurement technique. Surface roughness was examined using atomic force microscopy and scanning electron microscopy. Facet geometry (tip and valley radius) was quantified on cross-sectioned specimens. Molecular weight was compared between the incident and faceted surfaces of the lenses.

1-D and 2-D Monte Carlo simulations for analysis of CPV module characteristics including the acceptance angle impacted by assembly errors

CPV (Concentrator photovoltaic) requires accuracy in optical alignment. Optical misalignment in the module was measured and analyzed. Such information was useful to identify assembly problems and improved module performance.1-D and 2-D Monte Carlo simulations were developed to analyze the impact of alignment errors by assembly errors. The 1-D simulation was useful to anticipate the power output of the module, whereas 2-D was for acceptance angle.The 2-D model showed that the gap from Pmp-based acceptance angle (Pmp: Power at the maximum power point) from that of Isc-based (Isc: Short-circuit current) was a function of deviation of assembles misalignment in the module.The rough rule for the acceptable assembles misalignment is that the standard deviation of the assemble misalignment will be less than 10% of acceptance angle of the optics, whereas that of power output of the single module is 20%. This fact implies that the inspection of the acceptance angle is highly recommended in the CPV module production.

Static concentrator photovoltaics for automotive applications

This research investigated the benefits of utilizing solar power as an energy source for future passenger vehicles and an innovative static concentrator photovoltaic module for practical automotive applications. Due to strict emissions standards, alternative energy sources must be found for vehicles in the future. It was estimated that replacing all passenger vehicles with hybrid vehicles (HVs) equipped with an 800W rated-power solar module that generates an average output of 1.8kWh/day would reduce CO2 emissions by 63% in Japan. To confirm the validity of this estimation, a test vehicle was created by installing a 6.8m2 solar module onto a commercially available plug-in HV. An average power generation of 2.1kWh/day was obtained by this solar module over 100days under real-world conditions, which was larger than the power required to achieve the estimated CO2 emissions reduction. In addition, an innovative static low-concentrator with III–V cells was studied to help reduce the installation area of the solar module on the vehicles, which is essential for practical passenger vehicles. A new concentrator design method was proposed that can be easily integrated into a standard vehicle design procedure by utilizing numerical optimization in a CAD-friendly environment. Both design equations and a design example are discussed in this paper. The proposed lens design (asymmetric-aspheric type) can expand the acceptance incident angle of solar light and increase the annual energy yield of a solar panel, while maintaining the essential thin structure for automotive applications. In spite of the wide range of sun positions, this asymmetric-aspherical lens can maintaining stable illumination on the cell while suppressing the maximum spot intensity to 20×.

Design concepts for spillage recovery in a molten salt central receiver

This work evaluates concepts of hybridizing the molten salt central receiver design to recover spilled energy in an effort to reduce the electricity cost. The hybridization is done using existing technologies requiring marginal improvements. A simplified assessment is done to arrive at a target cost of two spillage recovery system without changing the prevailing levelized cost of electricity (LCoE) from the reference solar power plant. The target cost of the spillage recovery system using feedwater heater panels is $49M, whereas for concentrated photovoltaic modules, it is $40M. Integrating such systems with the tower type receiver below the target price is expected to reduce the LCoE of the plant. However, project specific conditions and requirements may also play an important role and should be taken into consideration with a more detailed overall plant level study to determine the feasibility of the hybridization concepts in a specific project.

Multiphysics modelling and experimental validation of high concentration photovoltaic modules

High concentration photovoltaics, equipped with high efficiency multijunction solar cells, have great potential in achieving cost-effective and clean electricity generation at utility scale. Such systems are more complex compared to conventional photovoltaics because of the multiphysics effect that is present. Modelling the power output of such systems is therefore crucial for their further market penetration. Following this line, a multiphysics modelling procedure for high concentration photovoltaics is presented in this work. It combines an open source spectral model, a single diode electrical model and a three-dimensional finite element thermal model. In order to validate the models and the multiphysics modelling procedure against actual data, an outdoor experimental campaign was conducted in Albuquerque, New Mexico using a high concentration photovoltaic monomodule that is thoroughly described in terms of its geometry and materials. The experimental results were in good agreement (within 2.7%) with the predicted maximum power point. This multiphysics approach is relatively more complex when compared to empirical models, but besides the overall performance prediction it can also provide better understanding of the physics involved in the conversion of solar irradiance into electricity. It can therefore be used for the design and optimisation of high concentration photovoltaic modules.

Dynamic Interferometry Lithography on a TiO2Photoresist Sol-Gel for Diffracting Deflector Module

Solar electricity is one of the most promising renewable energy resources. However, the ratio module’s cost/energy produced remains a major issue for classical photovoltaic energy. Many technologies have been developed to solve this problem, by using micro- or nanostructuring on the solar cell or on the module. These kinds of structuring are often used as antireflection and light-trapping tools. In the meantime, other solar technologies are considered, such as concentration photovoltaic modules. This article presents a module combining both approaches, that is, nanostructures and concentration, in order to increase the module’s profitability. Sol-gel derived TiO2diffraction gratings, made by dynamic interferometric lithography, are added on the top of the glass cover to deflect unused light onto the solar cell, increasing the module efficiency.