Direct Conversion Of Sunlight Research Articles

TOP ELECTRODE INVESTIGATION OF OPV MODULES BASED ON P3HT:PC[60]BM FABRICATED VIA ROLL-TO-ROLL PROCESS

Solar photovoltaic (PV) cells allow the direct conversion of sunlight into electricity without CO2 emission. Finding a way to cheaply utilize the vast amount of solar energy is one of the biggest challenges for this technology. The organic photovoltaic cells (OPV) are based on solution-processed photoactive polymers and can be fabricated via roll-to-roll (R2R) processes, which allow high production throughput with low costs. CSEM Brasil is building the foundations of future high-tech industries in Brazil and one of our key technology development areas is OPV modules production using R2R coating. In this work, polymer solar cells based on P3HT: PC[60]BM were prepared by R2R coating (electron transport, active and hole transport layers – ETL, AL and HTL) and by screen printing (top silver electrode). In order to save material and give more transparency of the OPV module were compared and evaluated the performance of two different suppliers of Ag paste (A and B) in three different top contact configurations, solid, grid and honeycomb. Additionally, were compared two different screen suppliers (I and II) for screen printing process and the Ag paste drying time studied. The comparisons were made with modules with an active area of 21.6 cm2 (6 stripes serially connected). Photovoltaic performance was evaluated in terms of Ag paste and screens suppliers, Ag pattern and drying time. Finally, modules were encapsulated in a R2R laminator using a flexible barrier film and evaluated in terms of lifetime.

Ordering Technique for the Maximum Power Point Tracking of an Islanded Solar Photovoltaic System

The world’s attention has turned towards renewable energy due to escalating energy demands, declining fossil fuel reservoirs, greenhouse gas emissions, and the unreliability of conventional energy systems. The sun is the only renewable energy source that is available every day for a specific period of time. Solar photovoltaic (PV) technology is known for its direct conversion of sunlight into electricity using the photoelectric effect. However, due to the non-linear electrical characteristics, the power output of solar PV cells is bound to a lower value and can not produce the power of which it is capable. To extract the maximum possible power, the PV cell needs to be operated at its maximum power point (MPP) uninterruptedly under numerous weather conditions. Therefore, an electronic circuit driven by a set of rules known as an algorithm is utilized. To date, the flower pollination algorithm (FPA) is one of the most renowned maximum power point tracking (MPPT) algorithms due to its effective tracking ability at the local and global positions. After an in-depth analysis of the design, strengths, weaknesses, and opportunities of the FPA algorithm, we have proposed an additional filtration and distribution process named “Random walk” along with the ordering of solutions, to improve its efficiency and tracking time. The proposed structure named “Ordered FPA” has outperformed the renowned FPA algorithm under various weather conditions at all the standard benchmarks. Simulations are performed in MATLAB/Simulink.

Impact of Interfaces, and Nanostructure on the Performance of Conjugated Polymer Photocatalysts for Hydrogen Production from Water

The direct conversion of sunlight into hydrogen through water splitting, and by converting carbon dioxide into useful chemical building blocks and fuels, has been an active area of research since early reports in the 1970s. Most of the semiconductors that drive these photocatalytic processes have been inorganic semiconductors, but since the first report of carbon nitride organic semiconductors have also been considered. Conjugated materials have been relatively extensively studied as photocatalysts for solar fuels generation over the last 5 years due to the synthetic control over composition and properties. The understanding of materials' properties, its impact on performance and underlying factors is still in its infancy. Here, we focus on the impact of interfaces, and nanostructure on fundamental processes which significantly contribute to performance in these organic photocatalysts. In particular, we focus on presenting explicit examples in understanding the interface of polymer photocatalysts with water and how it affects performance. Wetting has been shown to be a clear factor and we present strategies for increased wettability in conjugated polymer photocatalysts through modifications of the material. Furthermore, the limited exciton diffusion length in organic polymers has also been identified to affect the performance of these materials. Addressing this, we also discuss how increased internal and external surface areas increase the activity of organic polymer photocatalysts for hydrogen production from water.

Power Quality Improvement in Three-Phase Grid Connected Photovoltaic Cells using MMC with Fuzzy Logic Controller

In modular multilevel converter (MMC), the sub modules which perform switching actions, it may produce higher order harmonics when involved with fluctuating capacitor voltages and when it gets superimposed with the circulating currents, it will increase their magnitude which results into increased system losses. In this research work, we have implemented a repetitive control scheme which consists of three components: PI controller, moving average filter and repetitive controller. It is applied to MMC equipped with fuzzy controlled logic, which controls the harmonics by suppressing them up to a significant level. The proposed model is designed for three phase applications and the simulation results clearly define the effectiveness of the control mechanism. Photovoltaic’s (PV) is a method of generating electrical power by converting sunlight into direct current electricity using semiconducting materials that exhibit the photovoltaic effect. A photovoltaic system employs solar panels composed of a number of solar cells to supply usable solar power. Power generation from solar PV has long been seen as a clean sustainable [1] energy technology which draws upon the planet’s most plentiful and widely distributed renewable energy source – the sun. The direct conversion of sunlight to electricity occurs without any moving parts or environmental emissions during operation. KEYWORDS: MMC, Fuzzy Logic, Harmonic Suppression, Three phases, Repetitive Control, SIMULINK

Applications of solar PV tree systems with different design aspects and performance assessment

ABSTRACT Solar energy is deemed as the most abundant, reliable, eco-friendly and totally free resource of energy. There is a wide range of techniques to harness solar energy for different purposes. Among all the available methods, direct conversion of sunlight into electricity through photovoltaic (PV) phenomenon is the most mature and popular process. Progress of PV technology in market is perspicuous; however, it has still some drawbacks such as notable land requirement in cities, energy conversion efficiencies that already reached the theoretical limits and social acceptance issues due to aesthetic details. To overcome the aforesaid challenges, solar PV tree concept has been recently developed, and the simplicity, compact structure and elegance of this novel technology have been in the focus of researchers. Within the scope of this review, the concept of solar PV tree has been extensively investigated in terms of various design aspects and potential applications. Current performance characteristics of solar PV tree systems and power management strategies in real applications have been discussed. Challenges involved with the solar PV tree technology have also been addressed as well as suggestions on the direction of further works.

Anthracene‐based g‐C 3 N 4 photocatalyst for regeneration of NAD (P)H and sulfide oxidation based on Z‐scheme nature

Direct conversion of sunlight into value-added chemicals through artificial photosynthesis has been recognized as one of the most promising ways to address the global energy needs and to utilize the sustainable energy source. Even though the various semiconducting materials have been used for the solar-driven production of chemicals, many experimental efforts have been still focusing on developing clean and reusable photocatalysts. In this study, we report the new metal-free graphitic carbon nitride (g-C3N4) composite including anthracene moieties as a primary photosensitizer. The morphological and electronic structure of anthracene-based g-C3N4 (An-g-C3N4) composite were characterized by optical spectroscopies, electrochemical measurements, and theoretical calculations based on density-functional theory. The An-g-C3N4 composite exhibited outstanding photocatalytic efficiency for the regenerations of NAD(P)H cofactors owing to the prominent charge-transferred character and the superb light absorption. This study demonstrates that the catalytic reaction employing the combination of An-g-C3N4 photocatalyst and Z-scheme nature would be a suitable option for artificial photosynthesis.

COMPUTATIONAL SIMULATION MODEL FOR DYE ADSORPTION IN NANO TIO2 FILM FOR THE APPLICATIONS IN DYE SENSITIZED SOLAR CELLS

The theoretical and computational studies of dye sensitized solar cells (DSSCs) can contribute to a deeper understanding of these types of solar cells. The DSSCs are the novel design of solar cells which could be used as power producing windows or skylights. They represent a particular promising approach to a direct conversion of sunlight into electrical energy at low cost and with high efficiency. The light adsorption occurs in dye molecules adsorbed on a highly porous structure of TiO2 film. Despite the progress in the efficiency and stability of these solar cells, there is still a room of research on some of their operational aspects that are still not understood. One process, for which there is limited information, is the time taken to upload the dye on the TiO2 nanoporous film. The processes followed experimentally for dye uptake is by dipping the TiO2 semiconductor electrode into the dye solution for periods of several hours to several days. However, such long dipping times are not economical for industrial production of DSSCs. The factors controlling this process are not yet fully investigated. We propose a simple model based on the Langmuir isotherms to study and understand the diffusion and adsorption of the dye molecules in TiO2 films. Our computational modelling results show that the adsorption of dye into the TiO2 nanotubes film is controlled by the diffusion coefficient, the adsorption-desorption ratio and the initial dye concentration. Our results show that the initial dye concentration plays an important role on the surface coverage. It is also noted that for a higher concentration shorter immersion time is needed for the sufficient surface coverage. Furthermore, it is observed that for the large values of the adsorption-desorption ratio there is a delay in the diffusion of dye molecules on the surface.

Photocurrent generation of biohybrid systems based on bacterial reaction centers and graphene electrodes

The direct conversion of sunlight into chemical energy via photosynthesis is a unique capability of plants and some bacterial species. Aimed at mimicking this energy conversion process, the combination of inorganic substrates and organic photoactive proteins into an artificial biohybrid system is of a great interest for artificial bio-photovoltaic applications. It also allows to better understand charge transfer processes involved in the photosynthetic chain. In this work, single layer graphene (SLG) and multilayer graphene (MLG) electrodes are used as a platform for the immobilization of reaction centers (RCs) from purple bacteria Rhodobacter sphaeroides, a protein complex responsible for the generation of photo-excited charges. Electrochemical experiments with graphene electrodes and redox molecules reveal fundamental differences in the charge transfer processes for SLG and MLG films. We demonstrate that both graphene-based materials enable the immobilization of RCs without loss of functionality, attested by a photocurrent generation under illumination with IR-light at a wavelength of 870 nm. Furthermore, we report on the dependence of the generated photocurrent on the applied bias voltage, as well as on the presence of charge mediators in the surrounding electrolyte. This work demonstrates that SLG and MLG are a suitable platform for RC immobilization and subsequent photocurrent generation, suggesting a promising potential for graphene-based materials in bio-photovoltaics.

Grid-connected photovoltaic system design for local government offices in Nigeria

Photovoltaic is direct conversion of sunlight into electricity through electronic means that occurs at atomic level of semiconductors materials. It is neat, silent and elegant process of generating electric power in environmentally friendly manner. In this paper, the design analyses roof-mounted Grid-connected 148.5kWp Photovoltaic System with Energy Storage for use in a Local Government secretariat in Nigeria. The design was simulated using PV*SOL software to evaluate the system’s production performance and to know the amount of electric power generation for every day of the year. The result shows that the PV system’s daily production far exceeds energy demand in the building. The maximum monthly demand is 2893.22kWh while the least energy production is 13,802kWh which occur in July. The highest production occurs in November with 20,258kWh; followed by March energy yield of 20,053kWh. Hence, the system could serve as good revenue source for the government by exporting more than 75% of the power generated to the grid in exchange for good cash from electricity utility; while at same time serving as motivation for home owners in the community as well as other governmental offices to generate some or all of their energy need.Keywords: Photovoltaic, Photovoltaic design, Photovoltaic system, PV energy yield, Solar photovoltaic

Automated Calculation of Solar Electricity Systems in Russia as an Example of the Moscow Region

The development of modern energy is closely linked with the use of renewable energy. One of the leading trends in the field of renewable energy is photovoltaic , direct conversion of sunlight into electricity . Photovoltaic (photovoltaics) - the science that studies the process of converting sunlight into energy electric. Process is a direct conversion of sunlight into electrical energy using special semiconductor components. It is based on the physical phenomenon of the photoelectric effect - "pulling " electrons from a substance (silicon) under the action of light particles (photons) with the necessary energy (wavelength) .

A Bayesian approach for solar resource potential assessment using satellite images

The need for a more sustainable and more protective development opens new possibilities for renewable energy. Among the different renewable energy sources, the direct conversion of sunlight into electricity by solar photovoltaic (PV) technology seems to be the most promising and represents a technically viable solution to energy demands. But implantation and deployment of PV energy need solar resource data for utility planning, accommodating grid capacity, and formulating future adaptive policies. Currently, the best approach to determine the solar resource at a given site is based on the use of satellite images. However, the computation of solar resource (non-linear process) from satellite images is unfortunately not straightforward. From a signal processing point of view, it falls within non-stationary, non-linear/non-Gaussian dynamical inverse problems. In this paper, we propose a Bayesian approach combining satellite images and in situ data. We propose original observation and transition functions taking advantages of the characteristics of both the involved type of data. A simulation study of solar irradiance is carried along with this method and a French Guiana solar resource potential map for year 2010 is given.

Protein Delivery of a Ni Catalyst to Photosystem I for Light-Driven Hydrogen Production

The direct conversion of sunlight into fuel is a promising means for the production of storable renewable energy. Herein, we use Nature's specialized photosynthetic machinery found in the Photosystem I (PSI) protein to drive solar fuel production from a nickel diphosphine molecular catalyst. Upon exposure to visible light, a self-assembled PSI-[Ni(P2(Ph)N2(Ph))2](BF4)2 hybrid generates H2 at a rate 2 orders of magnitude greater than rates reported for photosensitizer/[Ni(P2(Ph)N2(Ph))2](BF4)2 systems. The protein environment enables photocatalysis at pH 6.3 in completely aqueous conditions. In addition, we have developed a strategy for incorporating the Ni molecular catalyst with the native acceptor protein of PSI, flavodoxin. Photocatalysis experiments with this modified flavodoxin demonstrate a new mechanism for biohybrid creation that involves protein-directed delivery of a molecular catalyst to the reducing side of Photosystem I for light-driven catalysis. This work further establishes strategies for constructing functional, inexpensive, earth-abundant solar fuel-producing PSI hybrids that use light to rapidly produce hydrogen directly from water.

Perovskite-related Oxynitrides in Photocatalysis

Over the last decades photocatalytic water splitting has become of increasing importance for fundamental and applied research, since the direct conversion of sunlight into chemical energy via the production of H2 has the potential to contribute to the world's energy needs without CO2 generation. One of the unsolved challenges consists of finding a highly efficient photocatalyst that is cheap, environmentally friendly, contains exclusively abundant elements, is (photo)chemically stable and absorbs visible light. Photocatalytic efficiency is closely connected to both structural properties like crystallinity, particle size and surface area and to electronic properties like the band gap and the quantum efficiency. Hence extensive control over a large parameter field is necessary to design a good photocatalyst. A material class where the structure-composition-property relations and the influence of substitution effects are well studied is the perovskite-type family of compounds. The perovskite-related oxynitrides belong to this very flexible compound family where many of the necessary characteristics for a photocatalyst are already given and some of the intrinsic properties like the band gap can be tuned within the same crystal structure by substitution. In this work we present materials' design concepts to improve the photocatalytic efficiency of a perovskite-type catalyst and describe their effects on the photocatalytic activity.

Effect of Manganese Concentration in the Cd1-xMnxTe/CdTe Tandem Structure on Photovoltaic Energy Conversion

The photovoltaic electricity is obtained by direct conversion of sunlight into electricity by solar cells. The objective of this work is the study and simulation of a Tandem photovoltaic structure based on Cd1-xMnxTe as top material cell.This paper describes the optimization of energy efficiency for Cd1-xMnxTe thin films deposited by epitaxy on CdTe substrat. We present the impact of the manganese concentration in Cd1-xMnxTe thin films on solar cells performances. Our study includes simulation results to show the conversion efficiency and main performances factors as function of the manganese concentration.

Engineering Enzymes for Energy Production

Harvesting the energy of sunlight can be achieved with a variety of processes and as one becomes obsolete, others will need to be developed to replace it. The direct conversion of sunlight into electrical energy could be used to provide power. Energy could also be obtained by combusting hydrogen produced by splitting of water with sunlight. None of these direct approaches will entirely satisfy the entire energy needs of a modern economy and the conversion of biological materials into liquid fuels for transport and other applications may prove to be important for tomorrow’s energy needs. In fact, biofuels such as bioethanol and biodiesel are already used in many countries. However, the long-term viability of these fuels depends on the efficiency of the processes used to produce them. We outline here a method by which ethanol can be produced using enzymes that can be optimized for this purpose.

Turning sunlight into electricity

The intensity of solar radiation in the Earth’s direction from the Sun is approximately 1353 kW/m2, a number also called the ‘solar constant’. Accordingly, it is estimated that Earth receives about 96 billion kilowatts from the Sun each second. If this colossal and unlimited energy could be more fully utilized, our dependence on fast dwindling fossil cache will be drastically reduced. Solar energy is available in various forms such as direct solar radiation, wind, wave power, rain (in the form of hydropower), photosynthesis and ocean thermal gradients. Among these, the direct conversion of sunlight into electricity is clean and attractive. This article highlights various routes to directly harness electricity from sunlight.

Energy for the Long Haul

![Figure][1] CREDIT: DAVID PAUL MORRIS/GETTY Perhaps the greatest challenge in realizing a sustainable future is energy consumption. It is ultimately the basis for a large part of the global economy, and more of it will be required to raise living standards in the developing world. Today, we are mostly dependent on nonrenewable fossil fuels that have been and will continue to be a major cause of pollution and climate change. Because of these problems, and our dwindling supply of petroleum, finding sustainable alternatives is becoming increasingly urgent. This special issue focuses on some of the challenges and efforts needed to harness renewable energy more effectively at a sufficient scale to make a difference and some of the people who are working on these problems. As introduced in the first News article (p. 782), the Editorial by Holdren (p. [737][2]), and the Perspective by Whitesides and Crabtree (p. [796][3]), many of the outstanding questions require major research efforts in underfunded areas. Much of the focus on sustainable energy is aimed at different ways of tapping into the most abundant renewable resource: solar energy. Lewis (p. [798][4]) points out that the direct conversion of sunlight with solar cells, either into electricity or hydrogen, faces cost hurdles independent of their intrinsic efficiency. Ways must be found to lower production costs and design better conversion and storage systems. In the short term, utilization of biomass relies mainly on sugar fermentation; Goldemberg (p. 808) discusses how Brazil's use of ethanol from sugarcane has greatly reduced its need for imported oil. Many long-term goals have been set for biomass utilization; for example, the European Union (EU) hopes to produce a quarter of its transportation fuels from biomass by 2030, as discussed by Himmel et al. (p. [804][5]). Better ways are also needed for processing the available sugars, and conversion to higher alcohols or even alkanes is desirable. Stephanopoulos (p. 801) explores the options afforded by reengineering biosynthetic pathways in microbes. How we tackle energy problems will turn on a number of policy issues. Poto ![Figure][1] nik (p. 810) discusses how the EU is setting targets and allocating funding for alternative energy. Finally, Schrag (p. [812][6]) explores the feasibility of sequestering carbon dioxide from fossil-fuel use and our technological readiness and willingness to implement such schemes. The News section profiles national lab directors, computer modelers, captains of industry, and bench scientists who are writing the early chapters of the next book on energy research. Some of them are developing better plants to grow as fuel or ways to convert them into ethanol. Others are developing catalysts to extract hydrogen from water or generate electricity from hydrogen. What they all share is a desire to find new ways to power the future. [ScienceCareers.org][7] takes a look at three young private-sector scientists who are on their first steps to careers in energy R&D: a consultant helping Israel meet its obligations under the Kyoto Protocol, a former particle physicist designing solar energy systems, and a Ph.D.-level engineer integrating sustainable electricity supplies into the power grid. [1]: pending:yes [2]: /lookup/doi/10.1126/science.1139792 [3]: /lookup/doi/10.1126/science.1140362 [4]: /lookup/doi/10.1126/science.1137014 [5]: /lookup/doi/10.1126/science.1137016 [6]: /lookup/doi/10.1126/science.1137632 [7]: http://sciencecareers.org/

Turning sunlight into electricity

The intensity of solar radiation in the Earth’s direction from the Sun is approximately 1.361 kW/m2, a number also called the ‘solar constant’. Accordingly, it is estimated that the power Earth receives is about 96 billion kilowatts from the Sun each second. If this colossal and unlimited energy could be more fully utilized, our dependence on fast dwindling fossil cache will be drastically reduced. Solar energy is available in various forms such as direct solar radiation, wind, wave power, rain (in the form of hydropower), photosynthesis and ocean thermal gradients. Among these, the direct conversion of sunlight into electricity is clean and attractive. This article highlights various routes to directly harness electricity from sunlight.

The Rise and Fall of the Appropriate Technology Movement in the United States, 1965–1985

Presidential Address THE RISE AND FALL OF THE APPROPRIATE TECHNOLOGY MOVEMENT IN THE UNITED STATES, 1965-1985 CARROLL PURS ELL Anchored in a period of social ferment and reform at one end, and in the Reagan years at the other, the two decades which saw the flourishing and the foundering of the Appropriate Technology movement in America encompassed also the end of the Vietnam War, a major energy crisis, and the first years of the environmental movement. The Appropriate Technology movement had its origins in perceived failings of the post-World War II technical aid efforts (by the United States and other northern hemispheric powers) in Third World countries but also quickly developed into a critique of American domestic technology. A welter of institutions were created: public and private; state, federal, and local; high-tech and low; aimed at underdevelopment overseas and overdevelopment at home. By the mid-1980s, however, most of these institutions had either disappeared or lost their momentum. The technologies themselves—solar energy, the generation of electricity by windmills, the utilization of abandoned dams for low-head hydroelectric generation, the development of methane gas and gasahol for fuel, a reemphasis on bicycles and mass transit, recycling and the use of natural materials, composting and sustainable (often organic) agriculture—survive, but without an ideological context which could give them political meaning.1 Dr. Plrsell is director of the Program in History of Technology and Science at Case Western Reserve University. He delivered this presidential address at the Society for the History of Technology meeting in Uppsala, Sweden, on August 19, 1992. 'For some recent expressions of a renewed interest in classic appropriate technolo­ gies, see “Neglected Agency May Get Vital Role in Energy Policy,” New York Times, November 23, 1992; “A New Era for Windmill Power,” New York Times, September 8, 1992; “Energy Efficiency—the Only Way Out,” Science 256 (June 12, 1992): 1515; “3 Utilities in California Plan Desert Solar Energy Project,” New York Times, August 29, 1992.© 1993 by the Society for the History of Technology. All rights reserved. 0040-165X/93/3403-0006$01.00 629 630 Carroll Pursell To explain the rise of Appropriate Technology, one must take into account the convergence of a broad countercultural movement, a reassertion of doubts about the role of technology in American life, and the burgeoning environmental movement. This rich nexus was easily labeled “antitechnology” but, in fact, embodied a critique of certain technologies and certain definitions of the word, rather than a rejection of technology as such. The decline of the movement can be attributed to a combination of political and cultural factors. On the one hand, despite initiatives at the state level and by PresidentJimmy Carter, there was a lack of political commitment to changing the economic subsidies (including federally funded research and devel­ opment budgets) that underwrote nuclear power, for example, but not the direct conversion of sunlight into electricity. Culturally, the campaign of the 1980s to “remasculinize” America after its defeat in Vietnam was profoundly antithetical to a movement that believed “Small Is Beautiful” and advocated “Soft Energy Paths,” to cite the titles of two of the most influential books in the literature of Appropriate Technology.2 It is difficult to imagine Rambo deliberately choosing to ride a bicycle, or recycle his cartridges, simply because such practices would be gentle on the earth. The debate over Appropriate Technology was rich in cultural meaning and ideological intent, as well as being a material and economic challenge to existing social interests. These interests were committed to a certain kind and understanding of technology which operated as a hegemonic culture, and to that privileged position the oppositional culture ofAppropriate Technology mounted a profound challenge. Since technological change can be understood in terms of not only social forces but also of cultural meanings, it pays to look especially at the contested definitions of words. In so doing one finds often enough that Appropriate Technology was represented as more feminine than the hegemonic technology and therefore seen by some as a threat to accepted notions of masculinity. The eclipse of Appro­ priate Technology in the 1980s became an important part of the so-called remasculinization of America. * * * Post-World...

Photovoltaic Technologies for Commercial Power Generation

Photovoltaic power generation is an attractive source of energy since it involves the direct conversion of sunlight into electricity with no moving parts and no pollution. Following the demonstration of the first solar cell 35 years ago at Bell Laboratories, a steady stream of scientific and commercial progress has led to a rapid increase in applications in recent years. The first commercial application of solar cells occurred more than 20 years ago when they were used to supply power for space satellites, and even today photovoltaic arrays are used to supply electricity for most satellites and space probes. This paper reviews the status of the various photovoltaic technologies as well as present applications. The prospects for both distributed and central station grid-connected systems are discussed. The paper concludes with a discussion of the institutional and political factors that will affect the introduction of grid-connected photovoltaic power systems.