Efficiency Of Solar Modules Research Articles

Periodic porous thermochromic VO2(M) films with enhanced visible transmittance

A periodic porous structure is introduced for the first time into a VO2(M) film to block only heat rather than light. The as-obtained 2D and 3D films show excellent visible transmittance and solar modulation efficiency.

Concentrated PhotoVoltaics (CPV): Is it a real opportunity?

Summary. — Many large industries made relevant investment in the field of CPV. Considering the present price of traditional silicon cells one could argue about this strategy. Critical points of CPV together with its benefits will be presented. In CPV more technology is involved compared to PhotoVoltaic (PV) and this could be the key issue. Moreover, progress in the field of multiple-juction solar cells is constant and efficiency is increasing every year. Good technical solutions could make CPV very competitive, provided it is installed in areas where the direct light (DNI) is relevant. 1. – Motivations Concentrated photovoltaics is based on the principle of concentrating sunlight on a smaller solar cell using cheap materials as molded plastics or aluminum to achieve a less expensive photovoltaics module. Moreover, using high-efficiency solar cells it is also possible to realize more efficient solar modules. The main idea is simple: to concentrate solar light using cheap optical elements such as mirrors or lenses over much smaller solar cells (down to 1/1000), and this to reduce the costs of installed power (and thus the costs of produced energy), see fig. 1. Photovoltaics based on silicon solar cells need large areas, due to its low (about 14%) efficiency. Concentrated photovoltaics can reach an efficiency near 30%, thus it needs less land for the same installed power; silicon solar cells have a large (about −0.3%) dependence of efficiency on temperature: this can be a real problem in very hot climates;

Study of the Effects Related to the Electric Reverse Stress Currents on the Mono-Si Solar Cell Electrical Parameters

The main objective of this work is to study, characterize finely the defects created in photovoltaic cells made from mono crystalline silicon wafer based on semiconductor has continued its operation under extreme conditions (electrical stress). We will demonstrate the effect of reverse stress current injected in solar cell structure on the I-V and C-V characteristics under dark conditions at room temperature for several time periods. These experimental measurements were numerical analyzed using double exponential model.Experimental evidence showed that different levels of reverse currents are confirmed to be a major degrading factor affecting the performance, efficiency, and power of solar modules. The experimental results were consistent with computational predictions.

All Fiber Laser Scribing of Cu(In,Ga)Se2 Thin-Film Solar Modules

Abstract State-of-the-art Cu(In,Ga)Se2 thin-film technology allows the industrial production of highly efficient solar modules. A significant growth of CIGS-based solar cell production volume can be expected for the coming years. One of the critical manufacturing steps in module production is thin-film patterning which allows the monolithic integration of cell-to-cell interconnects. Today, solar module manufacturers seek to replace sub-optimal needle scribing by suitable laser processes. It has been demonstrated, that ultra-short pulse laser scribing can reduce the overall width per interconnect and increase scribe quality. A promising tool for picosecond laser-scribing is the fiber laser. Here we present the successful implementation of all fiber laser patterning of CIGS modules.

High-Efficiency Solar Power Supply Design

In order to improve the efficiency of solar module, we have designed the Fresnel lens concentrated system and charging system, their schematic diagrams are depicted detailed in this paper. The experimental data show that adding Fresnel lens parts can improve the solar panels' power from 130% to 200% and incident angle can affect solar panels' voltage current characteristic deeply. All of these results can give some support to design the tracking system.

Selective Ablation in Cu(In,Ga)Se2 thin-film solar cells – analysis of different process regimes at sub-picosecond to nanosecond pulse duration.

Recent achievements in Cu(In,Ga)Se2 (CIGS) thin film technology allow the industrial production ofhighly efficient solar modules. A large growth of the CIGS-based solar cell production volume can beexpected for the coming years thanks to some favorable properties inherent to this absorber type. A majordrawback of CIGS is the inefficient patterning process. Since CIGS is a particularly difficult material forlaser ablation there is still no industrial all-laser scribing solution available. Manufacturers fall back onmechanical needle scribing for the P2 and P3 scribing process and have to accept substantial broadeningof the electrical interconnects due to unpredictable chipping at the scribe borders. In the present study weexplored a large variety of possible processes for the P1-P3 scribing at different wavelengths and indifferent pulse duration regimes. Beside the direct ablation of CIGS with ultrashort pulses we alsoinvestigated more exotic processes like layer side lift-off variants. The resulting scribes were analyzedusing electron microscopy (EM), laser scanning microscopy (LSM), energy dispersive X-ray spectroscopy(EDX) and electrical conductivity measurements. The most promising processes were selected forproducing functional mini-modules. Multiple optimization cycles allowed us to select the processes withthe best performance in the mini-module.

Omnidirectional study of nanostructured glass packaging for solar modules

ABSTRACTAntireflective light trapping glass nanostructures fabricated by a non‐lithographic process are investigated for their angle dependent properties to improve the omnidirectional performance of solar modules. Optical transmission and solar cell module I‐V measurements are used to understand the dependence of angular performance of nanostructures in the packaging glass. Nanostructures 100–400 nm in height demonstrate an increase in solar light transmission both for normal as well as oblique incidence and measurements show that a ~200‐400 nm nanostructure height is optimum for solar modules, providing an absolute increase of 1% in the power conversion efficiency at normal incidence and a gain in short circuit current density over a 120° angular cone of solar incidence. This shows that packaging glass texturing can be an important and often‐overlooked method to yield substantial gain in solar module efficiency. Copyright © 2012 John Wiley & Sons, Ltd.

Laser machined macro and micro structures on glass for enhanced light trapping in solar cells

In order to increase the efficiency of solar cell modules it is necessary to make the optimum use of light incident upon them. Much research has been done on improving light absorption through front surface texturisation and light trapping schemes. Laser light is commonly used in industry for various applications including marking and texturisation. By controlling laser parameters, it is possible to tailor macro and micro structures in most materials. The CO2 laser used in this investigation emits radiation at 10.6 μm with the ability to pulse in the micro-second range. The laser was used to ablate grooved textures in the fused quartz material, used in this study as the light trapping medium, following which an analysis of the effects of the laser parameters on the texture geometry and surface morphology was performed through a combination of cross sectioning and scanning electron microscopy. Transmission through the textured glass was improved for most samples after acid etching. The light trapping effects of the best performing textures were analysed by investigating the effects on a silicon solar cell’s performance at varying angles of incidence. Results indicated a significant increase in light trapping when light was incident at acute angles. For an angle of incidence of 10∘ a relative increase in efficiency of up to 51 % was observed.

The Performance of Three Different Solar Panels for Solar Electricity Applying Solar Tracking Device under the Malaysian Climate Condition

The main objective of this study was to measure and determine the efficiency of poly-crystalline, mono-crystalline and amorphous silicon solar module by applying single-axis time/date solar tracker to the installation of photovoltaic panel (dynamic system) as a strategy to increase the performance of the modules under hot-humid climate of Malaysia. The dynamic system in this experiment was designed to support the three types of PV panels which allowed it to move with single degree of freedom (horizontally) according to the sun’s orientation (sunrise to sunset) from east to west. Studies on sun movement in equator countries have been conducted to locate the sun‘s position on site (azimuth and altitude angle) using the Stereographic Diagram and Tabulate Daily Solar Data. It was found that poly-crystalline solar module have shown better performance ratio and average module efficiency compare to the others tested PV module under Malaysian climate.

Photovoltaic Materials and Devices

As the global energy needs grow, there is increasing interest in the generation of electricity by photovoltaics (PVs) devices or solar cells - devices that convert sunlight to electricity. Solar industry has seen an enormous growth during the last decade. The sale of PV modules has exceeded 27 GW in 2011, with significant contributions to the market share from all technologies. While the silicon technology continues to have the dominant share, the other thin film technologies (CdTe, CIGS, a-Si, and organic PV) are experiencing fast growth. Increased production of silicon modules has led to a very rapid reduction in their price and remains as benchmark for other technologies. The PV industry is in full gear to commercialize new automated equipment for solar cell and module production, instrumentation for process monitoring technologies, and for implementation of other cost-reduction approaches, and extensive research continues to be carried out in many laboratories to improve the efficiency of solar cells and modules without increasing the production costs. A large variety of solar cells, which differ in the material systems used, design, PV structure, and even the principle of PV conversion, are designed to date. This special issue contains peer-reviewed papers in the recent developmentsmore » in research related to broad spectrum of photovoltaic materials and devices. It contains papers on many aspects of solar cells-the growth and deposition, characterization, and new material development.« less

Enhanced chemical stability of VO2 nanoparticles by the formation of SiO2/VO2 core/shell structures and the application to transparent and flexible VO2-based composite foils with excellent thermochromic properties for solar heat control

Vanadium dioxide is a key material for thermochromic smart windows that can respond to environmental temperature and modulate near infrared irradiation by changing from a transparent state at low temperature to a more reflective state at high temperature, while maintaining visible transmittance. VO2 thermochromism is commonly used in films on glass that function as smart windows. Flexible VO2 nanocomposite foils are able to combine the intrinsic properties of VO2 nanoparticles with the added functionalities contributed by nanoscale and interface effects, such as increased visible transparency and infrared modulation ability. These foils are promising for applications in construction and automotive glasses to increase energy efficiency. However, VO2 nanoparticles may be unstable, and they are difficult to prepare in stable dispersive suspensions. In this paper, we report a novel all-solution process that can be used to prepare transparent, stable and flexible VO2-based composite films. These films exhibit UV-shielding properties and an excellent temperature-responsive thermochromism in the near infrared region. A typical film has a solar modulation efficiency of 13.6%, which is the highest value for VO2 thermochromic films with comparable visible transmittance. Coating the VO2 nanoparticles with a thin SiO2 shell significantly improved their anti-oxidation and anti-acid abilities. This result represents an important breakthrough in VO2 thermochromism, and it may have applications for near infrared modulation of glass used in construction or cars.

Solution-based nanoparticle approach to CIGS PV technology

Thin film photovoltaics (PV) based on chalcopyrite absorbers of Cu(In, Ga)(S, Se)2 (CIGS) have been the subject of intense research for their potential to achieve high efficiency solar modules with lower cost than the pervasive crystalline silicon panels. Having realised world record efficiencies surpassing 22%, the drive to reduce the cost of fabrication is just as vital to this technology. One such approach for reducing the cost is through the printing of the CIGS absorber layer using nanoparticle-based inks. This approach realises a number of advantages over traditional vacuum-based approaches and champion efficiencies reported here are fast approaching those achieved using vacuum techniques.

The Photoelectric Conversion Efficiency Research at Color Solar Cell

When the petrochemical raw materials continue to rise, resulting in the demand for solar power to increase 25-30% annually. So solar power is currently the most practical and efficient best alternative energy sources. silicon solar cells is now the main raw material, which can be divided into: single-crystal silicon, polycrystalline silicon and amorphous silicon. The most efficiency is single crystal silicon solar cells, polycrystalline silicon solar cells yield larger and more expensive, amorphous silicon solar cell has the lowest price but the worst efficiency. Solar module packaging can produce the required voltage and current, and blocking the water to increase product life. Because the color of solar cells are usually black, is not easy to integrate into the environment. If we can use color packaging material to make solar modules, will be applied to toys, gifts, landscape, lighting and other everyday products, resulting in a more perfect match. This article will explore a range of color package parameters and the relative conversion efficiency of solar cell modules.

The effect of reverse current on the dark properties of photovoltaic solar modules

Forward and reverse dark current-voltage (I-V) and capacitance-voltage (C-V) characteristics of commercial amorphous silicon solar modules, were measured in order to study their performance under the influence of induced reverse currents. Maximum module surface temperatures were directly related to each value of the induced reverse current and in to the amount of current leakage respectively. Microscopic changes as a result of hot spots defects and overheating of the solar module, linked to reverse current effects, were also documented and discussed. Experimental evidence showed that different levels of reverse currents are confirmed to be a major degrading factor affecting the performance, efficiency, and power of solar modules.

Solution-based fabrication of vanadium dioxide on F:SnO2 substrates with largely enhanced thermochromism and low-emissivity for energy-saving applications

Vanadium dioxide is a key material for thermochromic smart windows that can respond to environmental temperatures to modulate near infrared irradiation from a transparent state at low-temperature to an opaque state at high-temperature while maintaining the visible transmittance. This paper reports a novel VO2/FTO/glass multi-layered structure, which shows promising optical properties for application to energy-efficient smart windows. VO2 thin films are deposited on F-doped SnO2 (FTO) glasses by annealing a precursor film that is obtained via a solution-based process. The rutile-structured FTO substrate enhances the crystallinity of the VO2 films and lowers the synthesis temperature to ∼390 °C. The VO2/FTO/substrate double-layered films show both improved low-emissivity performance and distinct thermochromic properties. For a 65 nm thick VO2/FTO substrate double-layered film, low emissivities of 0.19 and 0.27 before and after the metal-insulator phase transition (MIPT) are obtained, while a solar transmittance modulation efficiency (η, in the wavelength range of 280–2600 nm) of 4.9% is achieved. A TiO2 anti-reflective coating (ARC) is incorporated to form a three-layered TiO2/VO2/FTO/substrate structure to boost the integrated visible transmittance (Tvis) while maintaining the low-emissivity performance. A 29.4% improvement for Tvis from 34.0% to 44.0% at room temperature is achieved for a 55 nm thick VO2 film coated with a TiO2 layer while emissivities of 0.13 and 0.24 before and after MIPT are maintained. Moreover, η is also increased significantly, from 4.3% for the VO2/FTO/substrate structure to 8.8% for the TiO2/VO2/FTO/substrate structure. Our results demonstrate a new approach of combining both thermochromism and low-emissivity performance for applications such as VO2-based energy-saving windows.

Reaction between oxide sealant and liquid electrolyte in dye-sensitized solar cells

The iodide and tri-iodide reduction–oxidation couples in the liquid electrolyte of dye-sensitized solar cells (DSSCs) are very reactive and corrosive with the other components of the DSSCs, especially the sealing material. A leakage of the liquid electrolyte to cells generally occurs in the DSSCs because of a chemical reaction between the sealing material and the electrolyte. This leakage is correlated to the long-term stability and energy conversion efficiency of the dye-sensitized solar module. This study examined the reactions between the electrolyte and the glass using a leaching test with the aim of using this material as the matrix of the sealing materials in DSSCs. The prepared samples were evaluated using an inductively coupled plasma spectroscope, a nanoindentation test, an atomic force microscope and a contact angle analyzer. After the leaching test, the zinc and boron ions from the glass were leached into the electrolyte after immersion for 1 h. The elastic modulus, hardness, and surface roughness of the glass changed after the formation of the leached layer of the glass surface. The results suggested that the compositions of the oxide sealant should be considered in terms of the chemical stability in the electrolyte.

High efficiency amorphous and nanocrystalline silicon solar cells

AbstractThis paper reviews our progress of using nc‐Si:H as a low bandgap absorber material to substitute for a‐SiGe:H alloys in multi‐junction solar cells. We have focused on three topics: (1) high deposition rate, (2) large area uniformity of thickness and material properties, (3) high solar cell and module efficiencies. Initially, we investigated various deposition methods, including RF, VHF, and microwave glow discharges. After several years of systematic studies, we have been convinced that VHF glow discharge is an applicable method to attain high rate and large‐area uniform nc‐Si:H depositions. We also studied the stability of nc‐Si:H solar cells and observed various metastability phenomena in nc‐Si:H solar cells. We have reported an initial active‐area cell efficiency of 15.4% using an a‐Si:H/a‐SiGe:H/nc‐Si:H triple‐junction structure. Subsequently, we have increased the deposition rates to around 1.0–1.5 nm/s and achieved an initial active‐area efficiency of 13.4% using an a‐Si:H/nc‐Si:H/nc‐Si:H triple‐junction structure. Recently, a stable total‐area efficiency of 12.5% was measured at NREL on our a‐Si:H/nc‐Si:H/nc‐Si:H triple‐junction solar cell. We have also developed large‐area VHF deposition systems and demonstrated encouraging module efficiencies using a‐Si:H/nc‐Si:H/nc‐Si:H triple‐junction structures. Initial and stable aperture‐area (400 cm2) efficiencies of 11.0 and 10.1% have been achieved with fully encapsulated modules with a‐Si:H/nc‐Si:H/nc‐Si:H triple‐junction structures. In this paper, various aspects of nc‐Si:H solar cells are discussed, including the material structures, device design, light trapping, metastability, high efficiency solar cell optimization, and large‐area deposition.

Thin Film Silicon Photovoltaic Technology – From Innovation to Commercialization

AbstractThe last decade has witnessed tremendous progress in the science and technology of thin film silicon (amorphous and nanocrystalline) photovoltaic. The shipment of solar panels using this technology was about 200 MW in 2009; based on announcement of new or expanded production capacity, the shipment is projected to grow ten-times in the next 3-5 years. The key factor that will determine the wide-scale acceptance of the products will be the cost of solar electricity achieved using this technology. Efficiency of solar modules and throughput of production equipment will play a key role. In this paper, we discuss our roadmap to improve the product efficiency and machine throughput.

Microstructure Design of Nanoporous TiO2Photoelectrodes for Dye-Sensitized Solar Cell Modules

The optimization of dye-sensitized solar cells, especially the design of nanoporous TiO2 film microstructure, is an urgent problem for high efficiency and future commercial applications. However, up to now, little attention has been focused on the design of nanoporous TiO2 microstructure for a high efficiency of dye-sensitized solar cell modules. The optimization and design of TiO2 photoelectrode microstructure are discussed in this paper. TiO2 photoelectrodes with three different layers, including layers of small pore size films, larger pore size films, and light-scattering particles on the conducting glass with the desirable thickness, were designed and investigated. Moreover, the photovoltaic properties showed that the different porosities, pore size distribution, and BET surface area of each layer have a dramatic influence on short-circuit current, open-circuit voltage, and fill factor of the modules. The optimization and design of TiO2 photoelectrode microstructure contribute a high efficiency of DSC modules. The photoelectric conversion efficiency around 6% with 15 x 20 cm2 modules under illumination of simulated AM1.5 sunlight (100 mW/cm2) and 40 x 60 cm2 panels with the same performance tested outdoor have been achieved by our group.

Recent developments of silicon thin film solar cells on glass substrates

Among various semiconductor technologies applied in photovoltaics, thin-film technologies offer several attractive features, both technically and economically. Recent developments of silicon thin-film devices predominantly based on amorphous silicon (a-Si), are described. Particular emphasis is placed on the importance of the substrates that consist of glass coated with a transparent conductive oxide (TCO) to serve as front contact layer of the photovoltaic film combination. The electrical conductivity and optical absorption of the TCO substantially affect the energy conversion efficiency of solar modules. An essential enhancement of the light absorption within the photoactive a-Si layer is derived from a surface texture of the TCO, that provides index-grading for lower front reflection, and light scattering to result in light trapping due to total internal reflections within the a-Si. The requirements for optimal TCO properties are reviewed in the context of their availability. Additionally, novel cell structures involving microcrystalline silicon, are expected to lead to higher efficiencies. Thin-film technologies, led by those based on a-Si, will take on an increased role in module production worldwide, which is consistent with favorable manufacturing cost expectations.