Performance enhancement of photovoltaic modules by nanofluid cooling: A comprehensive review

Only 15-20% of solar radiation incident on the photovoltaic (PV) cells is utilized which further reduces due to the rise in the temperature of the PV module and it also degrades the lifespan of the PV module. Therefore, numerous attempts were made to reduce this rising temperature of the PV module and different cooling techniques were employed. Nanofluid cooling is one of the potential cooling techniques for lowering the temperature of the PV module and augmenting the heat transfer by increasing the thermal conductivity of the nanofluid relative to the base fluid (BF). The experimental and numerical studies related to the cooling of PV cells with nanofluids have been reviewed. It was found that the heat transfer from the back of the PV module is enhanced with the augmentation in the concentration of nanoparticle in BF; however, some studies also demonstrate that the enhancement in the heat transfer also depends upon other factors such as the geometry at the rear of the PV module, nanoparticle material, nanoparticle size, BF, ambient conditions, etc. This review article also demonstrates the various issues with nanofluids such as instability, technological difficulties, high system costs, and the impossibility of finding a viable operational design which creates a barrier in the commercialization of the nanofluid cooling technique for PV modules.     

光伏电池最大功率点跟踪方法的研究

在光伏发电系统中,为了提高光伏电池的利用效率,需要对光伏电池的最大功率点进行跟踪。分析了在跟踪控制中常见的扰动跟踪法和功率数学模型法,比较了它们的优缺点,并基于这两种方法提出了一种改进的跟踪方法,利用MATLAB对该方法进行了仿真研究,仿真结果验证了该方法的有效性。     

A solar thermophotovoltaic converter using Pbs photovoltaic cells

A solar thermophotovoltaic converter using PbS photovoltaic cells is proposed. The converter is in the form of a flat plate consisting of a heat mirror, a black absorber, a cell filter and PbS photovoltaic cells. Theoretical analysis shows that, ideally, the efficiency of such a system is about 30%.     

Development process of solar photovoltaic system cooling technology

光伏系统在运行时,冷却太阳能光伏电池板使其达到更高的效率是一个关键因素。适当的冷却可以提高电力效率,并随着时间的推移降低电池退化的速度,从而使光伏组件的寿命最大化。综述了传统冷却技术中自然循环对流冷却、强制对流循环冷却和液冷技术,新型冷却技术浮动跟踪集中冷却系统、混合PV/T系统冷却、混合PV/TE系统采用散热器冷却以及通过使用相变材料来提高太阳能光伏电池板的性能。根据研究的重点、贡献和实际应用分析各技术的优缺点、适合应用的领域及各自技术的经济特点。未来的技术发展方向应是无论选择何种技术来冷却光伏板,都应该保持工作表面温度较低且稳定、简单可靠、能够利用提取的热能来提高整体的转换效率。     

基于太阳能光伏热利用的光伏/热电(PV/TV)建筑一体化试验研究

将太阳能电池板、集热器、热电发电片结合起来,设计并制成了一套光伏/热电(PV/TV)系统,在利用太阳能电池发电的同时,收集热量并利用其发电。在北京地区进行了该系统的室外模拟试验,测试并讨论了该系统在不同结构和不同环境下的性能,探讨该系统在光伏建筑中的应用。试验结果表明,与单纯的光伏发电系统或太阳能热水系统相比,PV/TV系统具有占地面积小、综合效率高等优点。     

Application of compound parabolic concentrators to solar photovoltaic conversion: A comprehensive review

The use of concentrating systems has been proposed as a way to reduce the cost of electrical energy from photovoltaic (PV) module. Since 1970s, different solar collector designs have been used to increase energy flux on the PV module. This study aims at providing a comprehensive review of development in the application of compound parabolic concentrators (CPCs) to solar photovoltaic conversion for the past five decades. By narrowing down the application of CPCs to electrical energy only gives a reader an opportunity to clearly understand the detail development stages, challenges, and research opportunities for further improvement. From this review, it has been found that during 1970s, all studies on the application of CPCs to solar photovoltaic conversion were mainly focused on establishing technical feasibility and cost effectiveness. Thereafter (1981‐May 2018), extensive studies were carried out to resolve challenges that were observed during the establishment stage. However, it has been found that even though the power output of the PV modules with the CPC was always higher than similar modules without the CPC, the values were less than the expected (theoretical) results. This was due to optical losses, series resistance losses, non‐uniform illumination effect, and high operating cell temperature effect. In addition, high cost of the PV‐CPC systems and low concentration ratio of the CPCs were also the main concerns of various researchers.     

A review on carbon nanotube/polymer composites for organic solar cells

Carbon nanotubes (CNTs) have unique properties, such as their electrical conductivity, that enable them to be combined with conducting polymers to form composites for use in organic solar cells (OSCs). It is envisaged that the improved composite has a higher efficiency of green energy and will reduce the cost of these cells. The use of such alternative energy sources also drastically reduces overuse of fossil fuels and consequently limits environmental degradation. This review compares research and performance between conventional silicon solar cells and OSCs. It also discusses OSC photoexcitation and charge carrier generation with the incorporation of CNTs, physicochemical properties of the composites and other factors that affect the efficiencies of OSCs. In addition, properties of CNTs that favour their dispersion in polymer matrices as acceptors and charge carriers to the electrodes are covered. The effects of CNTs containing dopants, such as nitrogen and boron, on charge transfer are discussed. Also, the fabrication techniques of OSCs that include CNT/polymer composite processing and the methods of film deposition on the substrate are described. Finally, the case studies of OSCs containing polymers with single‐walled CNTs, double‐walled CNTs or multi‐walled CNTs are evaluated. Copyright © 2014 John Wiley & Sons, Ltd.     

Nonfullerene organic photovoltaic cells exhibiting 13.76% efficiency by employing upside‐down solvent vapor annealing

Organic photovoltaic cells (OPVs) are fabricated with a polymer donor PM7 and a nonfullerene acceptor IT‐4Cl; the morphology of active layers is optimized by employing upside‐down solvent vapor annealing (UD‐SVA) method with different annealing solvents. The OPVs with CS₂ as annealing solvent exhibit optimized power conversion efficiency (PCE) of 13.76%, with simultaneously increased short‐circuit current density (J_SC) of 20.53 mA cm^?2 and fill factor (FF) of 77.05%. More than 15% PCE improvement can be achieved by employing CS₂ UD‐SVA treatment, which should be attributed to slightly enhanced photon harvesting, efficient exciton separation, charge transport, and collection, resulting from the well‐developed morphology of active layer. Moreover, the PM7:IT‐4Cl–based OPVs with CS₂ as annealing solvent still can maintain PCE more than 13% in a wide treatment time range from 20 to 90 seconds. This work demonstrated that UD‐SVA has great potential in improving the performance of nonfullerene OPVs.     

Patternable polymer bulk heterojunction photovoltaic cells on plastic by rotogravure printing

We study the fabrication of poly(3-hexylthiophene)—P3HT and [6,6]-phenyl-C61 butyric acid methyl ester—PCBM based polymer bulk heterojunction photovoltaic cells using rotogravure printing. By studying the dependencies of device performance on material and process parameters including contact angles, ink concentrations, ink viscosities, solvent characteristics, and gravure printing parameters, optimized hole transport layers [poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)—PEDOT:PSS] and active layers (P3HT:PCBM) are printed, resulting in devices with power conversion efficiencies as high as 1.68% under AM 1.5 G and a spectrally matched intensity of 100 mW/cm².     

A review on high performance photovoltaic cells and strategies for improving their efficiency

The introduction of a practical solar cell by Bell Laboratory, which had an efficiency of approximately 6%, signified photovoltaic technology as a potentially viable energy source. Continuous efforts have been made to increase power conversion efficiency (PCE). In the present review, the advances made in solar cells (SCs) are summarized. Material and device engineering are described for achieving enhanced light absorption, electrical properties, stability and higher PCE in SCs. The strategies in materials and coating techniques for large area deposition are further elaborated, which is expected to be helpful for realizing high-efficiency SCs. The methods of light-harvesting in SCs via anti-reflecting coatings, surface texturing, patterned growth of nanostructure, and plasmonics are discussed. Moreover, progress in mechanical methods that are used for sun tracking are elaborated. The assistance of the above two protocols in maximizing the power output of SCs are discussed in detail. Finally, further research efforts needed to overcome roadblocks in commercialization were highlighted and perspectives on the future development of this rapidly advancing field are offered.     

A critical review of electric vehicle charging using solar photovoltaic

The application of renewable sources such as solar photovoltaic (PV) to charge electric vehicle (EV) is an interesting option that offers numerous technical and economic opportunities. By combining the emission‐free EV with the low carbon PV power generation, the problems related to the greenhouse gases due to the internal combustion engines can be reduced. Over the years, numerous papers, including several review work, have been published on EV charging using the grid electricity. However, there seems to be an absence of a review paper on EV charging using the PV as one of the energy sources. With growing interest in this topic, this review summarizes and updates some of the important aspects of the PV‐EV charging. For the benefit of a wider audience, it provides the background on the EV fundamentals, batteries and a brief overview on the PV systems. Two types of PV‐EV charging, namely the PV‐grid and the PV‐standalone, are comprehensively covered. Moreover, a case study is carried out in comparison to the grid‐only charging to critically analyse the technical and the economical feasibilities of both types using Matlab simulation. At the end, recommendations and future directions are presented. It is envisaged that the material gathered in this paper will be a valuable source of information for the researchers working on this topic. Copyright © 2015 John Wiley & Sons, Ltd.     

Applications of carbon materials in photovoltaic solar cells

Carbon-based photovoltaic cells (PVCs) have attracted a great deal of interest for both scientific fundamentals and potential applications. In this paper, applications of various carbon materials in PVCs, especially in silicon-based solar cells, organic solar cells and dye-sensitized solar cells, are reviewed. The roles carbon materials played in the PVCs are discussed. Further research on solar cells comprised solely of carbon is prospected.     

Demand analysis for solar photovoltaic cells—a case study of Gundlupet Taluk

The demand for energy in India has been growing steadily over the years. Since conventional energy options have failed to cope with this increase, there has been growing interest in non-conventional energy sources. Solar photovoltaic (SPV) cells could be one such alternative energy source since solar energy is available abundantly in India. It is also renewable and non-pollutant. In this paper, estimation of demand for SPV cells in a drought-prone area of Karnataka State, Gundlupet, is projected for four identified market segments for the year 1996. Comparison of the cost of generation by SPV with that of conventional hydroelectricity with present and future costs is also made. The demand projections are encouraging for use of SPV cells. The projected cost of SPV energy by AD 2000 for amorphous silicon cells would be Rs 7·01 per kilowatt hour for a module price of Rs 55 per peak watt of power and a distance from the rigid of 3 km.     

Synthesis and photovoltaic properties of a star-shaped molecule with triphenylamine as core and benzo[1,2,5]thiadiazol vinylene as arms

A solution-processable and star-shaped molecule 4-((E)-2-(benzo[1,2,5]thiadiazol-4-yl)vinyl)-N,N-bis(4-((E)-2-(benzo[1,2,5]thiadiazol-7-yl)vinyl)phenyl)benzenamine (TPA-BT) has been designed and synthesized by palladium-catalyzed Heck reaction for the application in organic solar cells (OSCs). The molecule possesses a D-A structure with a triphenylamine core (donor unit) linked with three benzo[1,2,5]thiadiazole (acceptor unit) arms through double bonds. TPA-BT film shows a strong absorption peak in the visible wavelength range from 400 to 560 nm, which could be ascribed to the charge transfer band of the D-A structure of the molecule. The bulk-heterojunction OSCs with the device structure of ITO/PEDOT:PSS/TPA-BT:PCBM/Ca/Al (or Ba/Al) were fabricated by spin-coating the blend solution of TPA-BT and PCBM (1:3, w/w), in which TPA-BT was used as donor and PCBM as acceptor materials. The devices show a high open circuit voltage of ca. 0.9 V and a power conversion efficiency of 0.61%, under the illumination of AM 1.5, 100 mW/cm². The results indicate that TPA-BT is a promising solution-processable organic photovoltaic material.     

A review on photovoltaic/thermal hybrid solar technology

A significant amount of research and development work on the photovoltaic/thermal (PVT) technology has been done since the 1970s. Many innovative systems and products have been put forward and their quality evaluated by academics and professionals. A range of theoretical models has been introduced and their appropriateness validated by experimental data. Important design parameters are identified. Collaborations have been underway amongst institutions or countries, helping to sort out the suitable products and systems with the best marketing potential. This article gives a review of the trend of development of the technology, in particular the advancements in recent years and the future work required.     

Overview of printing and coating techniques in the production of organic photovoltaic cells

The organic photovoltaic cell (OPV) is composed of multiple layers, and some printing and coating techniques are more suitable than others for a certain type of layer. This paper aims to characterize and compare the most relevant coating and printing techniques that can be used in the manufacture of OPVs. Extensive bibliographic research was carried out on articles published from 1998 to 2020 to identify various aspects OPV, such as the principle of operation, advantages, disadvantages, and which layers can be printed by each technique. The results show that the most used method for the processing of OPVs is spin-coating. In the studies found, rotation was used to coat the active layer, the electron transport layer, and the hole transport layer. The techniques of pad printing, casting, and meniscus are considered useful in the processing of the active layer. Regarding the deposition of the active layer, hole transport layer, electron transport layer, and anode, the rotogravure, crack matrix, spraying, and brushing techniques were satisfactory. Flexography has been used to form the active layer, electron transport layer, and anode. Screen printing, inkjet printing, and knife/blade coating were used in the processing of the active layer, hole transport layer, electron transport layer, anode, and cathode. All the double slot die coating, curtain coating, and slide coating allows simultaneous processing of multiple layers. Techniques compatible with roll-to-roll processing are more likely to be at the center of OPVs in the future, thus making solar photovoltaic technology more competitive.     

Fabrication of organic photovoltaic cells with double-layer ZnO structure

The fabrication process of a photovoltaic cell with a structure of indium-tin-oxide (ITO)/double ZnO/C₆₀/poly(3-hexylthiophene) (PAT6)/Ag has been investigated. The C₆₀/PAT6 heterojunction of this cell was fabricated by spin-coating a chloroform solution of PAT6 onto the C₆₀ thin film formed on double-layer ZnO-coated ITO. The fabrication of this double-layer ZnO was a new method, which was a composite of a sputtered ZnO layer and oriented zinc oxide nanograins layer fabricated at low temperature (343 K). Insertion of the double-layer ZnO in the photovoltaic cells produced enhanced performance with the power conversion efficiency of 1.31% under AM1.5 illumination.     

Enhanced photovoltaic performance of inverted organic solar cells with In-doped ZnO as an electron extraction layer

In the present work, a systematic study has been carried out to understand the effect of In doping on the various properties of the ZnO nanocrystalline thin films. In-doped ZnO nanocrystalline thin films with different indium concentrations (1.98%, 4.03%, 6.74%, 8.62% and 10.48% In) have been synthesized by sol–gel method. The grain size and surface roughness of the In-doped ZnO thin films are observed to be smaller than those of the ZnO thin films. 6.74% In-doped ZnO films with a low resistivity of 1.95 × 10⁻³ Ω cm and a high mobility of 2.19 cm² V⁻¹ S⁻¹ have been prepared under optimal deposition conditions. Inverted organic solar cells containing In-doped ZnO as an electron extraction layer with the structure indium tin oxide (ITO)/In-doped ZnO/poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT): [6,6]-phenyl C₇₁-butyric acid methyl ester (PC₇₁BM)/MoO₃/Al have been fabricated. The inverted organic solar cell with 6.74% In-doped ZnO exhibited a power conversion efficiency of 5.58%, which is the best efficiency reported so far for these type of solar cells. The device performance has been optimized by varying the indium doping concentration. The results clearly demonstrate that significant improvement in power conversion efficiency can be obtained by incorporating In into the ZnO films.     

Advances in reduction of total harmonic distortion in solar photovoltaic systems: A literature review

The use of photovoltaic (PV) systems has increased in recent years due to the high demand for clean energy sources. PV systems can utilize abundant and free energy from the sun, which is a substantial advantage. However, compared with other renewable technologies, the PV system still faces major obstacles such as high cost and low efficiency. In addition, fluctuating incident energy from the sun creates harmonics in the generated power that might lead to undesirable system performance. Total harmonic distortion (THD) is the ratio of distorted power to the main power of the signal, and is most commonly used to indicate the amount of signal distortion. THD has become a serious concern as more PV systems are integrated into grid systems. Previous research and reviews have attempted to reduce THD and its effect, but unfortunately focused on reducing THD at individual parts of the PV system. For the first time, this study holistically and systematically reviews the advances in THD reduction techniques for the entire PV system. The causes of harmonics, current solutions, and research gaps for further investigation are described in detail. Moreover, the current THD reduction techniques used in each stage of the PV system are compared, including their main benefits and drawbacks. Finally, this study recommends the use of adaptive filters as a possible solution for THD reduction because these filters have effectively reduced noise and disturbance in other systems.     

Organic photovoltaic cells based on TPBi as a cathode buffer layer

The performance of organic photovoltaic (OPV) cells based on copper phthalocyanine (CuPc)/C₆₀ heterojunction was investigated by focusing on the role of 1,3,5-tris(2-N-phenylbenzimidazolyl) benzene (TPBi) as a cathode buffer layer. The effect of the film thickness of TPBi layer on the electrical characteristics of the device was systematically studied. The interface between the acceptor and cathode was studied with the characterization of atomic force microscope. Optical field distribution inside the OPV cell was also simulated to gain insight into the mechanism responsible for TPBi used as an optical spacer. The results indicated that at an optimal film thickness, TPBi cathode buffer layer is essential to enhance device performance by forming improved interfacial contact without introducing more series resistance and current loss.