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Wilfried van Sark

Bio: Wilfried van Sark is an academic researcher from Utrecht University. The author has contributed to research in topics: Photovoltaic system & Photovoltaics. The author has an hindex of 28, co-authored 107 publications receiving 2309 citations.


Papers
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BookDOI
01 Jan 2012
TL;DR: In this paper, a-Si:H/c-Si heterojunction and other high efficiency solar cells: a comparison of rear contact cells are presented. But the authors do not provide a detailed description of the interaction between the two heterojunctions.
Abstract: Foreword.- Introduction.- Status of heterojunction solar cell R&D.- Basic features of Heterojunctions illustrated by selected experimental methods and results.- Deposition methods of thin film silicon.- Electronic properties of ultrathin a-Si:H layers and the a-Si:H/c-Si interface.- Degradation of (bulk and thin film) a-Si and interface passivation.- Photoluminescence and electroluminescence for a Si:H/c Si device and interface characterization.- Deposition and properties of transparent conductive oxides.- Metallization and formation of contacts.- Electrical and optical characterization of a-Si:H/c Si cells.- Wet-chemical pre-treatment of c Si for a-Si:H/c-Si heterojunctions.- Theory of heterojunctions and the determination of band offsets from electrical measurements.- Modeling and simulation of a Si:H/c Si cells.- Surface passivation using ALD Al2O3.- Introduction to AFORS-HET.- Hands-on experience with simulation tools.- a-Si:H/c-Si heterojunction and other high efficiency solar cells: a comparison.- Rear contact cells.- Progress in systematic industrialization of Hetero-Junction-based Solar Cell technology.

190 citations

Journal ArticleDOI
TL;DR: An integrated blockchain-based energy management platform is proposed that optimizes energy flows in a microgrid whilst implementing a bilateral trading mechanism and total social welfare is found to be highest without a trading mechanism, however this platform is only viable when all costs are equally shared between all households.

168 citations

Journal ArticleDOI
TL;DR: A multi-objective Mixed Integer Linear Programming (MILP) optimization model is developed to minimize the operation costs and CO2-emissions of a community situated in Cernier (Switzerland), using different battery technologies in the CES system.

157 citations

Journal ArticleDOI
TL;DR: In this paper, the authors evaluate these projects by analyzing whether or not they strengthen the local Renewable Energy Innovation System and show that these projects strengthen most of the key processes necessary in an innovation system conducive to technology transfer, however, as not enough attention is being paid to local entrepreneurial activities and the creation of a domestic market for RETs, the process of RET transfer might run the risk of stagnation after completion of the RE programs.
Abstract: Like in many Small Island Developing States, the techno-economic potential of renewable energy technologies (RETs) in the Maldives is substantial However, it is not certain that these economically viable RETs will indeed be implemented and utilized, since this is greatly influenced by various social, institutional and political factors (ie, the Innovation System) In order to steer away from activities that enhance the current fossil fuel based lock-in situation and create an environment that increases the chance of a successful transfer and diffusion of RETs, several projects have been set up in the Maldives These projects have been initiated by the Global Environmental Facility, the United Nations Development Program, and the European Commission In this article we evaluate these projects by analyzing whether or not they strengthen the local Renewable Energy Innovation System This evaluation shows that these RE programs strengthen most of the key processes necessary in an Innovation System conducive to technology transfer However, as not enough attention is being paid to local entrepreneurial activities and the creation of a domestic market for RETs, the process of RET transfer might run the risk of stagnation after completion of the RE programs

136 citations

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate that type-II semiconductor hetero-nanocrystals may offer a solution to the self-absorption problem in luminescent solar concentrators.

130 citations


Cited by
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BookDOI
01 Oct 2012
TL;DR: The Global Energy Assessment (GEA) as mentioned in this paper brings together over 300 international researchers to provide an independent, scientifically based, integrated and policy-relevant analysis of current and emerging energy issues and options.
Abstract: The Global Energy Assessment (GEA) brings together over 300 international researchers to provide an independent, scientifically based, integrated and policy-relevant analysis of current and emerging energy issues and options. It has been peer-reviewed anonymously by an additional 200 international experts. The GEA assesses the major global challenges for sustainable development and their linkages to energy; the technologies and resources available for providing energy services; future energy systems that address the major challenges; and the policies and other measures that are needed to realize transformational change toward sustainable energy futures. The GEA goes beyond existing studies on energy issues by presenting a comprehensive and integrated analysis of energy chalenges, opportunities and strategies, for developing, industrialized and emerging economies. This volume is a invaluable resource for energy specialists and technologists in all sectors (academia, industry and government) as well as policymakers, development economists and practitioners in international organizations and national governments.

812 citations

Journal ArticleDOI
TL;DR: In this paper, the authors analyze data on 11 storage technologies, constructing experience curves to project future prices, and explore feasiblity of these technologies for decarbonizing personal transport and enabling highly renewable electricity systems.
Abstract: Electrical energy storage is expected to be important for decarbonizing personal transport and enabling highly renewable electricity systems. This study analyses data on 11 storage technologies, constructing experience curves to project future prices, and explores feasibl…

786 citations

Journal ArticleDOI
TL;DR: Recent advances in nanocrystal research related to applications of QD materials in lasing, light-emitting diodes (LEDs), and solar energy conversion are examined.
Abstract: The field of nanocrystal quantum dots (QDs) is already more than 30 years old, and yet continuing interest in these structures is driven by both the fascinating physics emerging from strong quantum confinement of electronic excitations, as well as a large number of prospective applications that could benefit from the tunable properties and amenability toward solution-based processing of these materials. The focus of this review is on recent advances in nanocrystal research related to applications of QD materials in lasing, light-emitting diodes (LEDs), and solar energy conversion. A specific underlying theme is innovative concepts for tuning the properties of QDs beyond what is possible via traditional size manipulation, particularly through heterostructuring. Examples of such advanced control of nanocrystal functionalities include the following: interface engineering for suppressing Auger recombination in the context of QD LEDs and lasers; Stokes-shift engineering for applications in large-area luminesce...

703 citations

Journal ArticleDOI
TL;DR: In this paper, a review of the use of the probability density function (PDF) of wind speed is carried out for a wide collection of models, and the methods that have been used to estimate the parameters on which these models depend are reviewed and the degree of complexity of the estimation is analyzed in function of the model selected.
Abstract: The probability density function (PDF) of wind speed is important in numerous wind energy applications. A large number of studies have been published in scientific literature related to renewable energies that propose the use of a variety of PDFs to describe wind speed frequency distributions. In this paper a review of these PDFs is carried out. The flexibility and usefulness of the PDFs in the description of different wind regimes (high frequencies of null winds, unimodal, bimodal, bitangential regimes, etc.) is analysed for a wide collection of models. Likewise, the methods that have been used to estimate the parameters on which these models depend are reviewed and the degree of complexity of the estimation is analysed in function of the model selected: these are the method of moments (MM), the maximum likelihood method (MLM) and the least squares method (LSM). In addition, a review is conducted of the statistical tests employed to see whether a sample of wind data comes from a population with a particular probability distribution. With the purpose of cataloguing the various PDFs, a comparison is made between them and the two parameter Weibull distribution (W.pdf), which has been the most widely used and accepted distribution in the specialised literature on wind energy and other renewable energy sources. This comparison is based on: (a) an analysis of the degree of fit of the continuous cumulative distribution functions (CDFs) for wind speed to the cumulative relative frequency histograms of hourly mean wind speeds recorded at weather stations located in the Canarian Archipelago; (b) an analysis of the degree of fit of the CDFs for wind power density to the cumulative relative frequency histograms of the cube of hourly mean wind speeds recorded at the aforementioned weather stations. The suitability of the distributions is judged from the coefficient of determination R2. Amongst the various conclusions obtained, it can be stated that the W.pdf presents a series of advantages with respect to the other PDFs analysed. However, the W.pdf cannot represent all the wind regimes encountered in nature such as, for example, those with high percentages of null wind speeds, bimodal distributions, etc. Therefore, its generalised use is not justified and it will be necessary to select the appropriate PDF for each wind regime in order to minimise errors in the estimation of the energy produced by a WECS (wind energy conversion system). In this sense, the extensive collection of PDFs proposed in this paper comprises a valuable catalogue.

690 citations

Journal ArticleDOI
TL;DR: In this article, the authors provide a detailed analysis of such optimum sizing approaches in the literature that can make significant contributions to wider renewable energy penetration by enhancing the system applicability in terms of economy.
Abstract: Public awareness of the need to reduce global warming and the significant increase in the prices of conventional energy sources have encouraged many countries to provide new energy policies that promote the renewable energy applications. Such renewable energy sources like wind, solar, hydro based energies, etc. are environment friendly and have potential to be more widely used. Combining these renewable energy sources with back-up units to form a hybrid system can provide a more economic, environment friendly and reliable supply of electricity in all load demand conditions compared to single-use of such systems. One of the most important issues in this type of hybrid system is to optimally size the hybrid system components as sufficient enough to meet all load requirements with possible minimum investment and operating costs. There are many studies about the optimization and sizing of hybrid renewable energy systems since the recent popular utilization of renewable energy sources. In this concept, this paper provides a detailed analysis of such optimum sizing approaches in the literature that can make significant contributions to wider renewable energy penetration by enhancing the system applicability in terms of economy.

635 citations