Concentrator Photovoltaic Research Articles

Study of luminescent coupling effect in modeling a concentrator photovoltaic system with III-V triple junction solar cell

Abstract A theoretical model is proposed for a concentrator photovoltaic (CPV) system. This model is based on the two-diode equation and considers the luminescent coupling (LC) effect in III-V triple junction solar cell. By using the model, the ‘I-V’ curve of the system is fitted. The fitting result is in good agreement with the experimental data. The system’s open circuit voltage is also predicted in a certain temperature range. Based on the analysis of the simulation results and the two-diode equation, it is concluded that the LC effect should be a non-negligible mechanism for analyzing the operation performance of CPV system.

Indoor performance analysis of genetically optimized circular rotational square hyperboloid (GOCRSH) concentrator

In the past few years, there was an increasing popularity of portable solar chargers for providing access to clean affordable electricity to remote locations in developing countries. Looking at the surge in demand, it is also important to reduce the environmental impact of portable solar chargers. Solar photovoltaic (PV) concentrators have the potential to reduce the embodied energy and thus the embodied greenhouse gas emissions, human-toxicity and eco-toxicity potential during production, recycling and disposal stages of silicon PV solar panels. Yet, no solar PV concentrator designs have been proposed for portable solar systems for developing countries. Recently, a novel concentrator known as genetically optimized circular rotational square hyperboloid (GOCRSH) concentrator was developed to address this problem. This paper evaluates the performance of four types of GOCRSH concentrators; namely GOCRSH_A GOCRSH_B, GOCRSH_Crh and GOCRSH_D that have a geometrical gain of 3.73x, 3.34x, 3.80x and 4.07x respectively. The experimental analysis of these concentrators was performed indoors under standard test conditions, i.e. 1000 W/m2, AM 1.5G and at a temperature of 25 ˚C to characterize the concentrators at normal incidence and to determine their angular response. Firstly, the fabrication process of the prototypes is described. Secondly, the GOCRSH concentrated devices and the reference cell are characterized at normal incidence, obtaining the current–voltage (I-V) and power-voltage (P-V) curves. Next, the angular response of the concentrators is obtained at various angles of incidence of up to ± 70° in increments of 5°. Mismatches between the simulation results and the experimental results are identified and possible error sources leading to the mismatch are discussed. Lastly, the increase in solar cell temperature under constant illumination and its impact on the solar cell performance is recorded for the GOCRSH_A concentrating device. From the indoor experiments, it was found that the prototypes were showing the maximum power point ratio under normal incidence of 2.9x, 2.6x, 3.9x and 2.7x with the GOCRSH_A GOCRSH_B, GOCRSH_Crh and GOCRSH_D respectively.

Integrating Concentrated Optics for Ambient Perovskite Solar Cells

Metal halide perovskite solar cells (PSCs) are considered an effectual way to enhance photovoltaic (PV) properties, leading to low-cost and high efficiency. PSCs have experienced rapid improvement in the last ten years. The device’s energy production increases extensively in the presence of concentrated light. The use of concentrated optics in solar cells has spurred the PV industry towards tremendous research. Incorporating the concentrated optic into the PV system as a concentrated PV (CPV) means it can capture light effectively and operate at increased efficiencies under concentrated irradiance. This work addresses an initial assessment of the power conversion efficiency (PCE) enhancement of the ambient PSCs by externally integrating concentrated optics. Significantly, the concentrated optics exhibit ~90% of the PCE enhancement under the solar irradiance of 400 W/m2, whereas 16% of the PCE increase was observed when the solar irradiance changed to 1000 W/m2. During optics integration, a considerable elevation of short-circuit current predominately facilitated the overall efficiency enhancement of the PSC. A systematic PV parameters effect on the optic integration on PSCs was further scrutinized. Therefore, this work signifies a possible way to alleviate the PCE of carbon-based PSC using concentrated optics. This work focuses on integrating CPVs into PSCs, preventing PSC stability and scalability issues, with light conditioning techniques.

A homogeniser inspired by the crustacean’s eye with uniform irradiance distribution and high optical efficiency characteristics for concentrated photovoltaics system

We devise an implicitly new design for boosting the light uniformity in the concentrated photovoltaics (CPV) system, whereby addressing the overheating issue of the PV cell and enhancing the electrical cell efficiency. Rather than using a well-known system of the Cassegrain concentrator design, consisting of double mirrors + a homogeniser, in this study, we mimic a structure of crustacean’s eyes for a design of homogeniser, consisting of an array of a mirror channel. Such proposed design allows making use of only a primary parabolic mirror + a homogeniser to concentrate and redistribute the sunlight, representing a large departure from virtually all of the previous studies. Specifically, such homogeniser can furcate the light beam into the small channels/trenches, redirect the light ray at the reflective plate and probably mix them to evolve a uniform version of light distribution. In general, the homogeniser can affect the uniformity and optical efficiency, which are good probes to assess the light performance, in a number of ways. We found that light performance depends sizably on the structural parameters such as the size and the number of channels of the homogeniser. The best structure displays a calculated uniformity of ~85% of the flux distribution on solar cell and a calculated optical efficiency of ~90% of the entire CPV system. We also assess the light performance against some scenarios of error in installation and operation processes such as tolerance and misalignment and compare well with the current design. The compelling of this proposed design is highly efficient light performance, compactness and inexpensive, which likely address virtually existing bottlenecks in the CPV system.

Mathematical Modelling of a Static Concentrating Photovoltaic: Simulation and Experimental Validation

For the past twenty years, there has been increasing interest and investment in solar photovoltaic (PV) technology. One particular area of interest is the development of concentrating PV (CPV), especially for use in building integration. Many CPV designs have been developed and investigated. This paper aims at producing a mathematical modelling using MATLAB programme to predict the current-voltage (I-V) and power-voltage (P-V) characteristics of a static CPV. The MATLAB programme could also simulate the angular response of the CPV designs-which has never been explored in the previous literature. In this paper, a CPV known as the rotationally asymmetrical dielectric totally internally reflecting concentrator (RADTIRC) was analysed. A specific RADTIRC design that has an acceptance angle of ±40° was investigated in this paper. A mathematical modelling was used to simulate the angular characteristics of the RADTIRC from −50° to 50° with an increment 5°. For any CPV, we propose that the value of opto-electronic gain, Copto-e needs to be included in the mathematical model, which were obtained from experiments. The range of incident angle (±50°) was selected to demonstrate that the RADTIRC is capable of capturing the sun rays within its acceptance angle of ±40°. In each simulation, the I-V and P-V characteristics were produced, and the short circuit current (Isc), the open-circuit voltage (Voc), the maximum power (Pmax), the fill factor (FF) and the opto-electronic gain (Copto-e) were determined and recorded. The results from the simulations were validated via experiments. It was found that the simulation model is able to predict the I-V and P-V characteristics of the RADTIRC as well as its angular response, with the highest error recorded for the Isc, Voc, Pmax, FF and Copto-e was 2.1229%, 5.3913%, 9.9681%, 4.4231% and 0.0000% respectively when compared with the experiment.

Concentrated photovoltaics as light harvesters: Outlook, recent progress, and challenges

Concentrated photovoltaics (CPV) is a dawn technology in the field of photovoltaic that helps in escalating the effective use of solar energy. Nowadays, applications of photovoltaic solar cells are catching attention due to the better utilization of solar energy. A huge amount of solar energy is received by the earth from the sun, but a barrier to the large-scale use of photovoltaic solar cells is their higher initial cost and lower conversion compared to other non-renewable energy systems. Concentrated Photovoltaics (CPV) is one of the vital tools that focus solar radiation on the small area of solar cells using optical devices to maximize solar to thermal conversion. Low cost, high efficiency, and climate-friendly are the main advantages of concentrated photovoltaics. The review study presents the outlook of work conducted worldwide on the different types of concentrated photovoltaics. In addition, the effect of various performance affecting parameters, challenges, and recent progress is also part of the study. Most of the CPV have efficiency up to 15% while some have an efficiency range of 25–28% which is still very low. It was found that the CPV gave maximum efficiency of up to 38.5% at optimal solar radiation. The focus of sunlight on a small area of solar cell increases the temperature of concentrated photovoltaic allegedly pernicious for electrical efficiency and the life of CPV. Factors like direct normal irradiance, high cell temperature, soiling, optical design, reliability, and durability are considered as challenges and a concise summary of various studies on these challenges is presented. In this regard, various cooling techniques have been investigated by different researchers for thermal management of CPV systems which are discussed in detail. As CPV technology is still in the development phase, various new optical designs emphasizing novel designs and materials are also summarized in the current study. Finally, some recommendations are oriented which will be very valuable for those who are working or want to work in the field of photovoltaics.

Concentrator photovoltaic thermal management using a new design of double-layer microchannel heat sink

The concentrator photovoltaic (CPV) systems commonly endure high cell temperatures, which affect their overall performance. Besides, the high cell temperature could lead to physical damages within the whole system due to the induced thermal stresses. Therefore, an efficient cooling is mandatory to achieve a higher net output power from the CPV and safe operation. The current work's main purpose is to investigate the integration of double-layered microchannel heat sink (DL-MCHS) with CPV cell as thermal management device. A three-dimensional (3D) model is presented to investigate the performance of a CPV cooled by the DL-MCHS to figure out the ability to handle the effective heat dissipation under different terrestrial conditions. The parallel flow (PF) and counter flow (CF) cooling orientations were studied. Ethanol coolant is used to cool the CPV under different concentration ratios (CR) of 5, 10, 15, and 20 suns. The results show that the temperatures remarkably decreases with the inlet flowrate is increased. The counter flow operation (CF) achieved the best temperature uniformity index (Tuni) when the coolant mass flowrate (V̇) ranged between 200 and 1200 ml/hr. Especially at CR 5 suns, the temperature uniformity index, Tuni, enhanced to 99.87% at 1200 ml/hr.

Three‐junction monolithic interconnected modules for concentrator photovoltaics

AbstractA core issue in concentrator photovoltaic technology (CPV) is the resistive losses in cells that usually limits the maximum photoconversion efficiency under high concentration. We propose the use of three‐junction monolithic interconnected modules (MIM) to mitigate resistive losses by providing high‐voltage low‐current power. First, we present the fabrication of InGaP/InGaAs/Ge front‐contacted microcells with various designs and dimensions. Front‐contacted cells are the key enabler for the MIM fabrication and demonstrate good electrical characteristics under one sun, similar to standard‐contacted cells. The base front contact size is minimized to limit the unutilized area on the wafer. Second, fabrication techniques for interconnecting cells in MIM are described. Finally, electrical measurements show a record conversion efficiency of 35.1% under 798 suns for the first three‐junction MIM reported (17.8% when considering the entire device area). Versatility and further optimization of the devices are discussed to enlarge their field of application.

Environments, needs and opportunities for future space photovoltaic power generation: A review

This paper aims to assess the potential and requirements of photovoltaic arrays to provide energy for more than 30 mission types to explore 14 celestial bodies in our solar system. The environment that exists at the Earth’s orbits, on the Martian and Lunar dusty surfaces, at the hottest Venus and Mercury, or among the distant Gas Giants, differs radically from one celestial object to another. In consequence, solar-powered spacecraft present many challenges and not all existing photovoltaic technologies have yet been optimized for such a wide variety of conditions. We address these challenges by reviewing the specific constrains of these worlds: solar irradiance levels, mission lifetimes, extreme temperatures and thermal cycling, as well as several specific characteristics such as radiation, chemical compounds, gravity, pressure, and dust. The suitability of photovoltaic arrays during past missions is examined by evaluating their behavior during their lifetime. A focus is made to study the feasibility of concentrator photovoltaics, which demonstrated record performances, reaching a cell efficiency of 47.1%. These systems do not seem to be adapted to missions with environments: highly scattered, with temperatures higher than 523 K and solar irradiances exceeding 3000 W/m2. However, some viable missions such as geostationary Earth orbit, deep space or moon bases can be successfully powered by concentrators. Key issues are addressed to enable the choice of materials and cell technology adapted to these specific missions. This paper presents a comprehensive review that can help spacecraft designers to use photovoltaic arrays to provide energy for space applications.

Feasibility analysis of a CPV system sized by means of a TJ cell black-box model and applied to a livestock farm welding

In the Concentrating Photovoltaic (CPV) systems, the Triple-Junction (TJ) cell electrical power is separately evaluated as function of its temperature or of the solar concentration factor (C), but generally not simultaneously as a function of both variables. Because all these variables are difficult to link by means of a white-box model, a mathematical model of the black-box type based on experimental data, is defined in this paper in order to link directly the TJ cell electric power together with Direct Normal Irradiance (DNI) and TJ cell temperature at different values of C. The knowledge of a link among TJ cell electric power, DNI and TJ cell temperature is basic to evaluate the real performances of a CPV system when it has to be sized, adopting a modular configuration, to meet the energy demands of a user. Hence, the feasibility of a CPV system adopted for an agricultural livestock farm located in Salerno (Italy), is evaluated by means of the model. The main activity of the farm is the breeding of cattle and sheep for milk production; the farm is made up of a stable and a farmhouse. The optimal number of TJ cells is defined to maximize the profitability of the investment, expressed in terms of Net Present Value. A CPV plant made up of 3000 cells, with an electric peak power of 6.6 kW, allows to maximize the NPV value up to about 16 k€.

Reliable planning of isolated Building Integrated Photovoltaic systems

Abstract In this paper, two probabilistic reliability indices are presented to define the effect of clouds on different types of Building Integrated Photovoltaic (BIPV) systems. Existing indices do not match the main features of photovoltaic (PV) sources, such as variability, uncertainty and dependency on weather conditions. In addition, they are time indicators that describe the percentage of total failure time per year without any indication about power or energy mismatch. By using the available Geographic Information System solar-irradiation database, the proposed indices consider a similar pattern of expected daily solar irradiation as a model of PV systems. Two different models are studied for diverse building loads: an energy model for flexible loads and a constant-power model for critical loads. A comparative study is implemented for six different locations: Cairo, London, Berlin, Beijing, Madrid and Riyadh. Moreover, three types of BIPV systems are studied: fixed, double-axis-tracking and concentrated PV systems. The presented results show the effects of clouds, PV type and locations on the system performance.

Simulation of steady-state characteristics of heterojunction perovskite solar cells in wxAMPS

Methylammonium lead iodide perovskite solar cells in a p-i-n configuration were modeled and simulated under steady-state conditions using wxAMPS software. The J-V characteristics and the power conversion efficiency of modeled devices were predicted under various operating conditions. The parameters adopted in the model were derived from the properties of the reported materials in the literature, and the simulated J-V curves were compared with experimental data. Detailed analyses were performed on the energy band diagrams, the distribution of the electric field, the profile of charge densities, and the rate of generation and recombinations under standard testing conditions and realistic operating conditions. The dark current was fitted to an ideality factor of 1.4, indicating that the recombination was via the SRH and band-to-band mechanisms. The optical generation process exhibited an exponential decay with an initial value of 1.5×1016 cm-3s-1, and the same magnitude of recombination was observed under open-circuit conditions. The roles of the anode and the cathode work functions (ΦITO, Φm) were examined. It was found when the ΦITO is greater than 5.2 eV together with Φm below 4.4 eV, an optimal PCE of 24 % can be obtained. Further, the device response under concentrated light was simulated in two steps with and without the presence of the alleviated temperatures. The results showed the PSCs have the potential to be used for concentrated photovoltaics if a cooling mechanism is provided or the cell is operated in a low-temperature ambient.

Exergo-economic optimization of concentrated solar photovoltaic and thermoelectric hybrid generator

Exergo-economic analysis of a concentrated photovoltaic–thermoelectric generator (CPV-TEG) hybrid system is investigated. The specific exergy costing is employed to study the cost effectiveness of the CPV-TEG system. A multi-dimensional single-objective optimization is carried out to optimize the CPV-TEG hybrid system. The performance of the CPV-TEG system is found to be better than that of the concentrated photovoltaic (CPV) system alone in terms of overall energy and exergy efficiencies. From an exergo-economic standpoint, the CPV-TEG system is more cost effective as compared to the CPV system alone. The low value of the exergo-economic factor of the system indicated that the associated cost was mostly due to irreversibilities in the system. A compromise is made by optimizing the CPV-TEG system for maximum exergy efficiency using an optimum thermal resistance of the thermoelectric generator (TEG). For the operating conditions and the geometry considered, integration of CPV and TEG is not found to be feasible (in terms of exegetic performance) below certain values of heat transfer coefficients (< 2500 Wm−2 K−1). A minimum value of heat transfer coefficient of 5266 Wm−2 K−1 is determined for a water-cooled heat sink to limit the cell temperature to 100 °C under the studied set of operating conditions and the geometric configuration. Optimization results yielded exergy efficiencies of 42.22% and 43.48% for the stand-alone CPV system and CPV-TEG system, respectively. The minimum costs of electricity under the optimum conditions were obtained as $$0.57\;\$ \; {\text{kW}}\,{\text{h}}^{ - 1}$$ and $$0.53\;\$ \; {\text{kW}}\,{\text{h}}^{ - 1}$$ for the stand-alone CPV system and CPV-TEG system, respectively.

The CPV “Toolbox”: New Approaches to Maximizing Solar Resource Utilization with Application-Oriented Concentrator Photovoltaics

As the scaling of silicon PV cells and module manufacturing has driven solar energy penetration up and costs down, concentrator photovoltaic technologies, originally conceived as a cost-saving measure, have largely been left behind. The loss of market share by CPV is being locked in even as solar energy development encounters significant obstacles related to space constraints in many parts of the world. The inherently higher collection efficiency enabled by the use of concentrators could substantially alleviate these challenges, but the revival of CPV for this purpose requires substantial reinvention of the technology to actually capture the theoretically possible efficiency gains, and to do so at market-friendly costs. This article will discuss recent progress in key areas central to this reinvention, including miniaturization of cells and optics to produce compact, lightweight “micro-CPV” systems; hybridization of CPV with thermal, illumination and other applications to make use of unused energy streams such as diffuse light and waste heat; and the integration of sun-tracking into the CPV module architecture to enable greater light collection and more flexible deployment, including integration into built structures. Applications showing particular promise include thermal applications such as water heating, industrial processes and desalination; agricultural photovoltaics; building-integrated photovoltaics with dynamic daylighting capabilities; and chemical processes including photocatalysis and hydrogen production. By appropriately tailoring systems to the available solar resource and local energy demand, we demonstrate how CPV can finally achieve real-world efficiencies, or solar resource utilization factors, far higher than those of standard silicon-based PV systems. This makes the argument for sustained development of novel CPV designs that can be applied to the real-world settings where this efficiency boost will be most beneficial.

Dynamics of Air Humidity in a Concentrator Photovoltaic Module with a Drying Device

We have studied the dynamics of air humidity in the interior of a concentrator photovoltaic (CPV) module equipped with air-drying device filled with moisture-absorbing material based on silica gel. A new design of the air-drying device was developed for preventing the deposition of condensate onto the surfaces of a Fresnel lens, solar cell, and CPV module. Under unfavorable ambient conditions (relative humidity up to 95%), this device allowed to reduce the inner humidity to 25–55% at cyclic temperature variation within 15–45°C and to increase the dew point deficit up to 10–25°C.

Ultrafast Many-Particle Phenomena in Lead Bromide Hybrid Perovskite Nanocrystals Under Strong Optical Excitation

In recent years, there has been a surge in research efforts to utilize organic−inorganic lead halide perovskites (OLHPs) in optoelectronic devices (e.g., concentrator photovoltaics) requiring high ...

Thermal analysis of a hybrid high concentrator photovoltaic/membrane distillation system for isolated coastal regions

The present study introduces an innovative method for fresh water and electricity generation in the isolated regions. This proposed system couples a concentrated photovoltaic (CPV) unit with a membrane distillation (MD) unit. The CPV unit converts solar energy into electrical energy with conversion efficiency of about 40%. The rest is converted to thermal energy, which may cause cells degradation if temperature exceeds manufacturer limits. An intermediate fluid is used as a coolant which transfers the excess energy to the feed of the MD unit through a heat exchanger. The generated thermal energy in the HCPV cells is used as the driving force for the distillation phenomena in the MD unit. Numerical models were built to simulate the hybrid system. It was found that, at a solar radiation concentration ratio of 1000 suns, the coolant flow rate should exceed 150 g/min for a maximum cell temperature less than 349 K. This arrangement should produce 177 W electric power, and 308 W thermal heat transferred to the coolant. At these conditions, the feed inlet temperature reaches about 323 K, at which, the MD unit produces about 5.88 kg/m2.h of pure water, thus allowing the system to simultaneously produce electricity and pure water for isolated coastal regions.

Fabrication of Fresnel lens arrays by a rapid non-isothermal imprinting process.

Fresnel lens arrays are widely employed in concentrator photovoltaics, photonic devices, and integral imaging systems. In this study, a rapid non-isothermal imprinting process for Fresnel lens arrays was proposed. In this process, a heated mold with microstructures was momentarily pressed onto a thermoplastic polymer surface that was initially kept at room temperature. The microstructures of the mold can be copied completely to the polymer substrate by imprinting consecutively until a continuous surface Fresnel lens array is obtained. Different from more traditional molding processes, the substrate does not need to be heated and cooled repeatedly in the replicating process. In addition, the imprinting process is carried out at room temperature, which can greatly reduce the thermal cycle time and energy consumption. Generally speaking, the material flow and stress distribution of the substrate need to be monitored so that the microlenses with a high precision surface finish can be produced in the non-isothermal imprinting process. To verify this, the finite element method (FEM) model for the non-isothermal process was established, and the feasibility of this process was analyzed. A hexagonal continuous surface Fresnel lens array was then fabricated, and its geometrical contour and imaging performance were tested. The experimental results showed this new process could be an effective and low-cost optical fabrication technology for high-quality production of Fresnel lens arrays.

Experimental study of the performance of concentrator photovoltaic/thermoelectric generator system integrated with a new 3D printed microchannel heat sink

Finding the most optimal configuration of hybrid concentrator photovoltaic (CPV)-thermoelectric power generator (TEG) system integrated with a microchannel heat sink (MCHS) is of great importance to achieve the best performance. Thus, two different hybrid configurations were chosen for the study including CPV/TEG/heat sink and CPV/heat sink/TEG. In addition, the performance of both hybrid configurations was compared with standalone CPV/heat sink and TEG/heat sink. In the conventional hybrid design, the TEG was directly attached to the back surface of the CPV module, whereas the other side of the TEG was integrated with MCHS. In the new hybrid design, the MCHS was sited between the CPV and the TEG module as both sides were subjected to concentrated solar radiation. Effects of varying the simulated solar concentration ratio, coolant flow rate on the solar cell temperature, and the total output power were experimentally determined. Results showed that the new design achieved a lower average solar cell temperature and a higher output power. At a solar radiation of 5000 W/m2, and a water flow rate of 80 g/min, the new design attained a solar cell temperature of 28°C with a conversion efficiency of 7.78% for the solar cell, and the total generated power was about 386 W/m2. In addition, the increase in the applied heat flux to the TEG unit to 10 000 W/m2 increased the total output power from 386 to 440 W/m2. Accordingly, the selection of an effective heat sink to absorb all the excess heat that emanated from the TEG side is of great importance to enhance the output electrical power generated by hybrid systems.

A critical review on measures to suppress flow boiling instabilities in microchannels

Due to the development of the electronic components, concentrator photovoltaic, fuel cell, etc., the cooling requirement of the devices increases rapidly. Due to the higher heat transfer and compact design of the microchannel technology, it has been widely considered and investigated to solve the increasing heat flux. Boiling heat transfer is an effective way to dissipate a mass of heat using the latent heat of phase change. Hence, comparing with the single phase liquid flow, flow boiling in microchannel utilizes both advantages of micro scale effect and phase change effect, and can realize a much higher heat flux. Therefore, it becomes a critical way for super high heat dissipation. However, the procedure of the phase change and two phase flow may lead to instability, which can seriously inhibit the heat transfer performance of coolant in microchannel. To tackle with the flow boiling instability, a number of methods were proposed and reported. Therefore, in this paper, to effectively improve the flow boiling in microchannel heat exchanger, the cutting-edge control technologies in this field were reviewed, categorized and summarized, and the future trend of the research was presented.