Concentrator Photovoltaic Module Research Articles

Multi-junction solar cell measurements at ultra-high irradiances for different temperatures and spectra

This paper reports experimental results on the impact of the temperature and spectral conditions on the behaviour of III-V multi-junction solar cells, employed in concentrator photovoltaic modules, operating under ultra-high concentration (UHC) conditions. The electrical parameters of the I–V curves of a 3-junction solar cell were measured using an experimental set-up based on a multi-flash indoor solar simulator, which allows adjustment of the cell operating temperature up to 85°C and reaching irradiance concentration levels up to 2200 suns under controlled spectral conditions. The measurements presented are unprecedented, as there are no previous publications that combine different spectral and temperature-controlled experimental conditions in the UHC range, thus extending the range of studies reported in works carried out at lower concentrations.

Tracking-Integrated CPV Technology: State-of-the-Art and Classification

Concentrator photovoltaic (CPV) technology offers an alternative to conventional photovoltaic systems, focusing on the concentration of solar radiation through the optics of the system onto smaller and more efficient solar cells. CPV technology captures direct radiation and requires precise module orientation. Traditional CPV systems use robust and heavy solar trackers to achieve the necessary alignment, but these trackers add to the installation and operating costs. To address this challenge, tracking-integrated CPV systems have been developed, eliminating the need for conventional trackers. These systems incorporate tracking mechanisms into the CPV module itself. This review presents a detailed classification of existing designs in the literature and provides an overview of this type of system with different approaches to integrated tracking including tracking concentrator elements, using external trackers, or employing internal trackers (the most researched). These approaches enable the automatic adjustment of the CPV system components to follow the movement of the Sun. The various tracking-integrated systems have different designs and performance characteristics. Significant progress has been made in developing tracking-integrated CPV systems with the aim to make CPV technology more competitive and expand its applications in markets where traditional CPV has been excluded.

Translation of outdoor tandem PV module I–V measurements to a STC power rating

AbstractThe procedures for the power rating of tandem‐cell‐based concentrator photovoltaic (CPV) modules defined in the international standard IEC 62670‐3 are adapted to the requirements of tandem‐cell‐based flat plate PV modules. The adjusted procedure describes how to translate outdoor measured PV current–voltage characteristics to standard test conditions (STC): 1000 W/m, 25°C cell temperature, AM1.5g spectral conditions. In this work, we describe how to obtain all required input parameters: thermal transient measurements to determine the module temperature coefficients, categorizing and filtering the prevailing spectral irradiance conditions using spectral matching ratios, and determining the 25°C module open‐circuit voltage from dark current–voltage curves. Three specimen PV modules (triple‐junction, III‐V on Silicon and III‐V on Germanium) have been measured for several months outdoors on a dual axis tracking unit at Fraunhofer ISE in Freiburg. In this work, we demonstrate that the CPV module power rating procedures in IEC 62670‐3 are also—in a modified form—to be recommended for the outdoor rating of tandem‐cell‐based flat plate PV modules.

Technological advancements and research prospects of innovative concentrating agrivoltaics

Agrivoltaic is a strategic and innovative approach that combines photovoltaic (PV) energy conversion with agricultural production, enabling synergies in the production of food, energy, and water, as well as the preservation of the ecological landscape. Shading management, intensity adjustment, and spectral distribution allow innovative PV systems to generate significant amounts of electricity without affecting agricultural production. Demonstration projects have already been developed around the world and there is a wealth of experience with various design solutions for commercial use. One of these new technologies is concentrator photovoltaics (CPV). The CPV has excellent spectral processing capabilities and highly concentrated power generation efficiency, which makes it a perfect solution for integrating with photosynthesis. This study aims to present the working principle of CPV modules considering agricultural applications and discuss the recent advancements in concentrating agrivoltaics. In this method, the problem of shading is mitigated by two main strategies: (i) parabolic glasses covered with a multilayer dichroic polymer film that reflects near-infrared (NIR) radiation onto the solar cells installed at the focal area and transmits photons in the range of photosynthetically active radiation (PAR), and (ii) highly transparent sun-tracking louvers or Fresnel lenses that concentrate direct sunlight onto the solar cells to generate electricity. In the latter solution, the remaining diffuse sunlight is directed to the ground for use by growing plants. Although the CPV development trend has been slow due to the lower cost of crystalline silicon, the development of CPV for agriculture with accurate spectral separation could revitalize this industry. In this regard, more research and development are needed to evaluate the suitability of materials that split solar radiation and their impacts on the electrical performance of CPV modules, taking into account the physiology of plants.

Predicting entropy generation of a hybrid nanofluid in microchannel heat sink with porous fins integrated with high concentration photovoltaic module using artificial neural networks

This paper evaluates the characteristic of second law of thermodynamic, including Bejan number and entropy generation for hybrid nanofluid containing graphene-silver nanofluid through a MCHS whit porous fins. Finite-volume technique is utilized to solve the governing equations. To simulate the problem, different porous medium thicknesses, nanoparticle concentrations, and inlet mass flow rates are used while the heat flux remains constant. The minimum values of the frictional and thermal entropy generation are 5 × 10−4 and 6.25 × 10−2, while the maximum values are 3.2 × 10−4 and 9.75 × 10−2. With increasing nanoparticle concentration up to 0.06% wt at constant porous thickness tp=200 µm, frictional entropy generation rises up by 3 × 10−5 and heat transfer rate go up while, thermal entropy generation decreases by 1.5 × 10−2. In addition, by doubling the input mass flow rate and reaching 0.02% at constant nanoparticle concentration (0.06%), thermal entropy generation decreases by 2 × 10−2 while the frictional entropy generation increases by 2.4 × 10−4. The minimum magnitude of Bejan number is 0.994. This show that the irreversibility is derived significantly from thermal entropy generation rate. Finally, an artificial neural network is employed to obtain a model for entropy generation.

Investigation of focusing properties of photovoltaic module concentrator in a wide temperature range

In the current work properties of a solar radiance concentrator with Fresnel lens made of Elastosil RT604 silicon made by Wacker have been investigated. The dependence of concentrator focal distance on temperature has been determined. Impact of variation of temperature-dependent concentrator focusing properties on the magnitude of short current of photovoltaic submodule has been determined by direct measurements using solar simulator. Using formalized model of modules based on the studied concentrator and solar cells with three and six p-n- junctions dimensions of a solar image in a wavelength range corresponding to an absorption profile of individual p-n- junctions has been calculated for the temperature range 10-60oC. It has been concluded that in the case of three p-n- junctions the minimum size of solar image at focal plane was 4.7 mm with the distance between the concentrator and solar cell being equal to 106.25 mm, and in the case of six p-n- junctions, the minimum size was 4.8 mm with the distance between concentrator and solar cell being equal to 106.5 mm. Keywords: silicone lens, Wacker RT604, concentrator photovoltaic module, multijunction solar cells.

Determination of individual I(V) characteristics of each sub-cell of a triple junction device

Very high conversion efficiency is reached with triple junction solar devices integrated in concentrator photovoltaic (CPV) modules. However, reduction of the active area for micro-CPV applications increases the perimeter/area ratio, enhancing losses linked to the edges. It is therefore important to characterize the perimeter influence on the final conversion efficiency. For this purpose, I(V) characterization under dark and/or light could be used as a test of the sidewalls influence. We have designed an experiment to perform I(V) curves using the light of three lasers with adjustable powers at 405, 785, and 980 nm, preferentially absorbed by the top, middle or bottom junction of the device, respectively. This experiment was applied to commercial devices made from a stack of GaInP/GaAs/Ge. In parallel we have developed a numerical calculation modeling the device to reproduce the behaviors observed during I(V) experiments. Junction parameters and influence of leakage resistances are deduced from the fit of experimental results with the numerical calculation. The I(V) experiment as well as the numerical calculation are presented in details. It is also underlined that, combining both experiment and calculation, the I(V) characteristic of each junction as if it was isolated can be determined.

Исследование концентраторных фотоэлектрических модулей с отражающими элементами вторичной оптики

The characteristics of concentrator photovoltaic modules based on a 120 × 120 mm Fresnel lens with secondary concentrators in the form of hollow aluminum focons with internal mirror walls are studied. The optimal sizes and configurations of secondary concentrators are determined to increase the efficiency of focusing systems of concentrator modules. The maximum value of the allowable misorientation angle was obtained, equal to ±0.75°, corresponding to a power drop to a level of 90% relative to the maximum power value of the concentrator photovoltaic module at normal beam incidence. For a module with the most efficient focon 40 mm high and side face slope angles of 17°, the maximum efficiency of the module under laboratory conditions was obtained, equal to 35.15%. Under natural conditions, the efficiency value reached 33.8 The results obtained correspond to the level achieved for the best foreign analogues.

Solar to hydrogen efficiency of 28.2% under natural sunlight achieved by a combination of five-junction concentrator photovoltaic modules and electrolysis cells

A combination of five-junction concentrator photovoltaic modules and electrolysis cells achieved a record high solar to hydrogen efficiency of 28.2%.

Performance analysis of a novel solar cogeneration system for generating potable water and electricity

PurposeThe utilisation of renewable energy sources for generating electricity and potable water is one of the most sustainable approaches in the current scenario. Therefore, the current research aims to design and develop a novel co-generation system to address the electricity and potable water needs of rural areas.Design/methodology/approachThe cogeneration system mainly consists of a solar parabolic dish concentrator (SPDC) system with a concentrated photo-voltaic module at the receiver for electricity generation. It is further integrated with a low-temperature thermal desalination (LTTD) system for generating potable water. Also, a novel corn cob filtration system is introduced for the pre-treatment to reduce the salt content in seawater before circulating it into the receiver of the SPDC system. The designed novel co-generation system has been numerically and experimentally tested to analyse the performance at Karaikal, U.T. of Puducherry, India.FindingsBecause of the pre-treatment with a corn cob, the scale formation in the pipes of the SPDC system is significantly reduced, which enhances the efficiency of the system. It is observed that the conductivity, pH and TDS of seawater are reduced significantly after the pre-treatment by the corncob filtration system. Also, the integrated system is capable of generating 6–8 litres of potable water per day.Originality/valueThe integration of the corncob filtration system reduced the scaling formation compared to the general circulation of water in the hoses. Also, the integrated SPDC and LTTD systems are comparatively economical to generate higher yields of clean water than solar stills.

Low‐cost outdoor spectral irradiances determination and its application on Concentrator Photovoltaic module power rating and energy yield calculation

AbstractIn this work, a method to calculate the aerosol content in the atmosphere and the prevailing spectral irradiance of the sunlight is introduced. This method does not aim for low measurement uncertainty but for cost effectiveness and does not require sophisticated equipment. The bases of the method are the clear sky direct normal irradiance (DNI) and a look‐up table calculated with the software tool SMARTS2. The ratio of clear sky DNI to the prevailing DNI in combination with the look‐up table allows the determination of aerosol optical depth (AOD), spectral matching ratios (SMR), and spectral irradiances. Besides the prevailing DNI, the following ambient condition parameters are required: Air pressure, relative humidity, and ambient temperature. This means a weather station and a pyrheliometer are sufficient for the determination of the prevailing spectral irradiance. Obviously, this method cannot guarantee the same accuracy as conventional spectral irradiance measurement methods (e.g., using a spectroradiometer). However, in this work, we demonstrate the potential of this new method as a fall‐back strategy for missing spectral irradiance data. This method is worth using when (C)PV module power output data needs to be evaluated in dependence of the composition of the spectral irradiance, but no regular spectral irradiance data are available. In this paper, the AOD and SMR values determined with the introduced method are compared to measurement data with common measurement devices demonstrating a satisfying agreement. The spectral irradiances calculated with this method are successfully tested for using as the basis for energy yield calculations and for the determination of the CPV module power output at Concentrator Standard Conditions according to IEC 62670‐1.

Numerical investigation of a photovoltaic module under different weather conditions

In this study, a numerical investigation of the uncooled polycrystalline concentrated photovoltaic (CPV) module was established using ANSYS software. The main objective is to estimate the maximum allowable solar concentration ratio (CR) at which the CPV module can safely operate without overheating. The numerical model was validated using data from the literature, resulting in a very good agreement. The thermal and electrical performance of the CPV module was studied at different ambient temperatures (0, 10, 20, 30, and 40 °C), wind speeds (1, 2, 3, 4, and 5 m/s), and CR number of (1.0,1.5, and 2.0 suns). This smaller CR can be achieved using a compound parabolic concentrator (CPC). The CPV system can safely operate when CR ranges from 1.0 to 1.5 suns, (1 Sun = 1000 W/m2), at all studied values of ambient temperatures and wind speeds. However, increasing the CR up to 2.0 makes results in a safe operation at wind speed values from 3 to 5 m/s. Further, the electrical efficiency increases rapidly by increasing the wind speed from 1 to 2 m/s and this increase gradually drops by growing the wind speed from 3 to 5 m/s. Furthermore, the minimum solar cell efficiency reached 12.56% at CR of 2.0 and 1 m/s. The highest heat dissipation from the CPV module is occurred at the lower ambient temperature and gradually decreases as wind speed rises.

Parametric study for optimizing double-layer microchannel heat sink for solar panel thermal management

The most significant issue affecting the electric efficiency of solar panels is overheating. Concentration photovoltaic (CPV) modules work by converting approximately 80% of sunlight to heat; this may exceed the cell operating temperature limits. Therefore, thermal management is the best choice for keeping such panels working under specified conditions. Prior to producing an actual solar indoor unit, the current research primarily focuses on optimizing the heat sink dimensions that affect the cooling performance of the solar panel. Two parametric studies were employed to optimize the microchannel heat sink design. First, a two-dimensional numerical study was implemented to optimize the best channel height for more uniform flow inside a double-layer microchannel heat sink (DL-MCHS); the width of channels was kept as a constant value. Second, a three-dimensional conjugate heat transfer model for fluid flow in the optimized heat sink was used to optimize the inlet/outlet header length. To evaluate the overall CPV performance, a further numerical case study was carried out for the optimized designs at a wide range of inlet mass flow rates and steady-state heat flux. The findings indicated that a channel height of 0.5 mm and a header length of 20 mm were the best design points for the suggested heat sink. To assess the effectiveness of a solar/thermal module, the selected design points were applied to a 3D model. The maximum electricity efficiency measured was 17.45%, nearly 40% greater than the typical CPV/T system.

On-site characterization of misalignments between concentrator photovoltaic modules installed on trackers

This paper deals with the characterization of misalignments between CPV modules installed on tracker structures, for which a misalignment measurement method (suitable for inspecting CPV plants) is proposed. The method consists of acquiring images of the photovoltaic solar cells magnified through the optics with a visual camera mounted on a drone. The relative position between modules is proportional to the observed spatial misplacement between the magnified cells and equivalent to an angular misalignment of the pointing vector of the modules with respect to the ideal optical axis. The method, that had already been demonstrated at module level in laboratory conditions, has been adapted to account for the errors associated to the camera position during the drone flight sequence. An experimental validation of the method is carried out by characterizing the misalignments between 48 CPV modules in a tracker, with an uncertainty lower than ±0.09 degrees for measured misalignments of up to 0.95 degrees.

Forecasting solar-to-hydrogen and solar-to-methane energy conversion efficiency using Si and IMM PV-modules: A case-study in Japan

The solar-to-gas (StG) conversion system is a potential pathway for accelerating zero-carbon energy sources. In our previous study, outdoor StG conversion was accomplished using triple-junction concentrator photovoltaic (CPV) modules. The system achieved the highest performance with sets of DC/DC converters and electrochemical (EC) cells. Therefore, we aimed to investigate the prospective StG conversion from PV systems if such a system is installed in Japan. A power generation prediction model considering all weather conditions, called the Miyazaki Spectrum to Energy (MS2E), has been developed using the METPV-11 meteorological database at the University of Miyazaki. Accordingly, the amount of energy generated by various PV systems could be forecasted nationwide from the global irradiance data. In this study, we applied the MS2E PV energy prediction method and approached the potential StG conversion efficiency of silicon (Si) PV and inverted metamorphic (IMM) PV systems across Japan. Based on the actual StG measurement data, we approximated the conversion of each subsystem. The simulation results show that IMM modules can provide higher StG conversion than Si modules.

Investigation of the feasibility and potential use of sun tracking solutions for concentrated photovoltaic Case study Fez Morocco

This paper investigates the requirements, the feasibility and reliability of concentrator photovoltaic (CPV) with trackers in Fez city (Morocco) climate. In a first step, an appropriate sun tracker for a CPV prototype is design-simulated and then, based on finite element analysis, the effect of wind velocity distribution induced charge on the global structure (tracker and CPV module) is investigated for several elevation angle of the CPV unit. For all the investigated configurations, the maximum simulated misalignment still negligible, and is estimated to 4.6 × 10−6°, for a wind speed of 3.3 m/s. As a result, it is anticipated that the examined high CPV system (HCPV) will works safely under these effects. In a second step, using a home-developed Python code, and geometrical solar equations, calculations have been performed to estimate the diffuse, the direct and the global irradiations in this location. Ultimately, the energy performance of the system using System Advisor Model (SAM) software is carried out and compared to some on site real measurements. This simulation process led to a rigorous evaluation of the potential energy production with a tracked CPV panel, proving its viability in Fez Morocco. It also shows the level of accuracy of at least 0.5° that sun-tracking photovoltaic systems are necessary to maintain the least amount of power yield loss, especially for CPV facilities. This research will also serve as a valuable guide for the future sun-tracking CPV system.

Performance analysis of a ball lens as secondary optical element for a micro photovoltaic concentrator

Concentrated Photovoltaic (CPV) is a promising technology for higher efficiency power generation than other photovoltaic power generating technologies. However, the lack of demand and its failure in the commercial field is mainly due to its long-term reliability issues as well as its cost, which is an order of magnitude higher than the other technologies. Therefore, several measures have been taken to minimize the cost, improve the reliability as well as improve the performance of these concentrators. In this approach, Micro photovoltaic concentrators have been introduced as an outstanding alternative to shed light on all these challenges while keeping the same principle as the CPV modules. This paper presents a theoretical analysis of a micro photovoltaic concentrator system with a geometrical concentration ratio of 100x consisting of a Plano-convex lens as a primary optical element, a ball lens as a secondary optical element, and a solar cell. The aim is to present a compact module with high optical efficiency, low thermal stress, and high mechanical tolerance to keep the optimum optical alignment between the submillimeter cell and the small-sized optics.

Numerical and experimental performance evaluation of a laser-concentrated photovoltaic-thermoelectric generator hybrid system.

Thermal management of concentrated photovoltaic (CPV) modules is essential to avoid the decrease in conversion efficiency caused by temperature rise during their operation. This is even more important for laser-concentrated CPV hybrid systems where out-of-control temperature rise is more likely to happen. In this research, a three-dimensional simulation model for a concentrated photovoltaic-thermoelectric (CPV-TE) hybrid system was studied to optimize its parameters and improve its conversion efficiency under laser radiation. Based on the simulation results, an integrated CPV-TE device was designed, fabricated, and tested under a high-power laser. The novel integrated CPV-TE system utilizes growing electrodes to encapsulate CPV directly on the TEG. Compared to conventional CPV-TE systems that utilize silicone-filled, the integrated CPV-TE system reduces contact thermal resistance and increases output power as well as conversion efficiency. To the best of our knowledge, this is the first study to discuss and optimize a CPV-TE hybrid system for laser radiation. In addition, this research improves the efficiency of laser energy conversion, increases the reliability and stability of the system, and may facilitate the promotion of optical wireless and fiber power transmission systems in future applications.

A novel variable-height-pinfin isothermal heat sink for densely-packed concentrated photovoltaic systems

A major limitation of liquid cooling is that the temperature of the coolant rises down the stream, which gradually reduces the heat transfer from the heat source to the coolant causing a large temperature gradient (or temperature non-uniformity) along the flow direction. In this study, a technique has been presented to efficiently minimize the temperature non-uniformity of liquid-cooled heat sinks by incorporating simple geometrical modifications. The technique is demonstrated for a densely-packed concentrated photovoltaic module (CPV) by using a heat sink with cylindrical pinfin microstructures. Several cases of the proposed variable height pinfin (VHP) heat sink were investigated by systematically varying the height of pinfin rows to gradually reduce the heat transfer near the inlet zone while keeping the heat transfer near the outlet zone as close as possible to the conventional uniform height pinfin (UHP) heat sink. The heat sinks were designed for a CPV module consisting of an array of 5 × 5 multi-junction photovoltaic cells illuminated under a solar concentration of 1000 suns. The results showed that the best case of the VHP heat sink achieved a variation of merely 1.56 K in the maximum temperature among the cells, which is 84.1% lower than the UHP heat sink (9.82 K). Moreover, the same case exhibited a 33.1% reduction in the pumping power. However, there is a 2.4% increase in the maximum temperature rise among the cells which is an acceptable tradeoff considering the substantial improvement in the temperature uniformity and pumping power.

Development and Accuracy Assessment of a High-Precision Dual-Axis Pre-Commercial Solar Tracker for Concentrating Photovoltaic Modules

In recent decades, advances in the development of solar tracking systems (STSs) have led to concentrating solar technologies to increase their energy conversion efficiency. These systems, however, still have areas of opportunity or improving their performance and reducing their manufacturing costs. This paper presents the design, construction and evaluation of a high-precision dual-axis solar tracking system with a technology readiness level of 7–8. The system is controlled by a low-cost Arduino board in a closed-loop control using a micro-electromechanical solar sensor. Real-time tracking experiments were performed under a clear sky as well as during partly and mostly cloudy days. Solar tracking accuracy was evaluated in an operational environment using test procedures adapted from the International Electrotechnical Commission (IEC) 62817 standard. The total mean instantaneous solar tracking error on a clear day measured with a calibrated digital solar sensor was 0.37° and 0.52° with a developed pinhole projection system. Similarly, the total mean reported solar tracking accuracy achieved was 0.390° on a sunny day and 0.536° on a partially cloudy day. An annual power generation analysis considering a conventional photovoltaic (PV) panel system and a typical concentrator photovoltaic (CPV) module as payloads was also presented. Simulations showed an increase in the generation of up to 37.5% for a flat panel with dual-axis tracking versus a fixed panel. In the case of the CPV system, first, a ray tracing study was implemented to determine the misalignment coefficient, then the annual power generation was estimated. The developed STS allowed the CPV modules to reach at least 90% of their nominal energy conversion efficiency.