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[en] The rapid development of photovoltaics boosted by attractive feed-in tariffs caused a sharp increase in requests for connection to public distribution grids, which were originally designed to serve consumers. ERDF, main distribution network operator in France, is facing a challenge in terms of capacity for handling requests for connection and in terms of public distribution network operation and management. (author)
[en] In this article the author takes a timely look at the latest trends in the inverter market, and discusses some of the irregularities in global grid regulations that affect these essential elements of photovoltaic (PV) systems. The inverter is by far the most complicated part of a PV system, as it has a wider range of functions to perform than any other component in the system. The inverter has to act as the interface between the PV modules, the load and the grid (or batteries). It also has to cope with variations in the electricity it receives due to varying levels of solar radiation, varying loads and varying grid voltages. The inverter takes most of the burden of meeting the complicated sets of regulations relating to electrical safety and power quality. These regulations vary from country to country, making the job of inverter manufacturers many times more complicated that they would be in an ideal world. The author goes into some detail about the regulation differences in Europe and the USA, market trends and the future for inverters is also discussed
[en] For a thermoelectric device driven by the temperature difference between soil and ambient air, previous analytical work has been performed wherein a sinusoidal surface boundary condition was imposed; the results suggested that optimal placement of the lower terminal of the device should be at a nondimensional depth of x* = 2.28, resulting in a 7% increase in power over placement at a much greater depth. Analysis of temperature data taken in conjunction with operation of a thermoelectric device has shown that the optimal depth for the lower thermal reservoir is much shallower than originally thought (x* ∼ 1), with increases in performance approaching 70% over that experienced at greater depths. Representative data are presented and interpreted, along with recommendations for future work.
[en] In the incipient world of functional industrial ceramics with photovoltaic applications, there is a need to reduce production costs while maximizing the systems useful life. The thin contact layers currently being manufactured are based on vacuum systems with high production costs and major problems of accelerated corrosion in photovoltaic applications. The electroless process produces very even and compact layers with very low costs through chelate-based chemicals. These layers have been formulated in this study with a view to obtaining appropriate electric characteristics for an optimum photoelectric performance in the assemblies. The morphological requirements are previously fitted through a glaze that acts as a barrier layer between the deposited coating and the porcelain tile, applied through tape casting. The characterisation of the metal layers obtained is started by SEM, an AFM and the Hall effect in order to determine the morphology and chemical characteristics required for these contact layers. The electric characterisation also allows their capacity for offering an optimum performance in the assemblies to be assessed. Finally, the performance of these layers with respect to corrosion is assessed in order to complete the assessment of their industrial suitability. (Author) 13 refs.
[en] This paper first proposes a modeling framework to study diffusion of innovations which exhibit strong interaction with the institution systems across which they diffuse. A unique character of such generic innovation is that specific applications are continually developed during its diffusion. This self-propagation in continual applications generation, which is dependent upon the cumulative installed base of the technological innovation, can be modeled to lead to a dynamic changing carrying capacity in an otherwise simple logistic diffusion curve. The cumulative installed base is dependent upon the price of technology and the cost learning dynamics. This paper utilizes a multi-factors learning function to represent such learning dynamics. Empirical estimates from our model are compared with those from other logistics curve formulations and are shown to better fit the annual PV production data during the past quarter century in the case of Japan. The very fact that the potential of this class of innovation can be leveraged only if it interacts closely with the institution highlights the importance of institutional determinants of adoption and diffusion of such innovations like PV. We therefore attempt to put forward an institutional framework, based on viewing PV as a technology platform, to consider PV diffusion beyond mathematical and empirical modeling. Some future research directions are also proposed. (author)
[en] Nano-materials present an important development potential in the field of photovoltaic conversion in opening new outlooks in the reduction of the solar energy cost. The organic or hybrid solar cells principle is based on the electron-hole pairs dissociation, generated under solar radiation on a conjugated polymer, by chemical species acting as electrons acceptors. The two ways based on fullerenes dispersion or on TiO2 particles in a semi-conductor polymer (MEH-PPV, PVK) are discussed. The acceptors concentration is high in order to allow the conduction of the electrons on a percolation way, the polymer providing the holes conduction. A new preparation method of the mixtures MEH-PPV/fullerenes based on the use of specific solvents has allowed to produce fullerenes having nano-metric sizes ranges. It has then been possible to decrease the fullerenes concentration allowing the dissociation and the transport of photoinduced charges. The way based on the in-situ generation of TiO2 from an organometallic precursor has allowed to obtain dispersions of nano-metric inorganic particles. The optimization of the photovoltaic properties of these nano-composites requires a particular adjustment of their composition and size ranges leading to a better control of the synthesis processes. (O.M.)
[en] Photovoltaic is developing in response to 3 requirements: conservation of the environment, security in energy, and economic growth. Given this, the terawatt (TW) scale should be used to measure the magnitude of energy needs. Can solar, in particular photovoltaic, power meet these needs? This has nothing to do with the availability of solar energy - in a single hour, the sun sends to the earth as much energy as the electricity consumed by all of humanity during an entire year. Instead, it raises questions about the industrial deployment and, eventually, the availability of raw materials and land. The sustainable development of photovoltaic power implies wisely using resources (raw materials, energy and capital) and improving the efficiency not only of the process for transforming resources into photovoltaic units but also of the photovoltaic units themselves for converting light into electricity. It is worth noting that the predictable change of scale in the photovoltaic industry will have implications for this industry's deployment on a large scale. This deployment depends on: the availability of technology, know-how, capital and raw materials; the cost of investments; the speed of implementation; and the rhythm of production of cells. (author)
[en] High resolution dopant profiling in semiconductor devices has been an intense research topic because of its practical importance in semiconductor industry. Although several techniques have already been developed, it still requires very expensive tools to achieve nanometer scale resolution. In this study we demonstrated a novel dopant profiling technique with nanometer resolution using very simple setup. The newly developed technique measures the thermoelectric voltage generated in the contact point of the SPM probe tip and MOSFET surface instead of electrical signals widely adopted in previous techniques like Scanning Capacitance Microscopy. The spatial resolution of our measurement technique is limited by the size of contact size between SPM probe tip and MOSFET surface and is estimated to be about 10 nm in this experiment
[en] The underlying technologies existing at the present time for making space nuclear power systems (NPS) based on thermionic energy conversion allow their application for creation of planet surface power complexes (PC) within the range of electric power from several tens to several hundreds kilowatts with operating life no less than 10 years under the conditions of operation at lunar and Martian surface. Such technologies include technologies of compact nuclear reactors on intermediate and fast neutrons, thermionic energy conversion in multi-element cylindrical converters built-in into reactor core, heat transfer by liquid metal coolants, heat removal by heat pipes and so on. In designing the following main requirements were taken into consideration: level of PC output electric parameters, mass and dimension limitations on PC constituent parts during transportation, reliability requirements, conditions for ensuring nuclear and radiation safety. The PC based on in-core thermionic reactor consists of reactor unit, external radiation shield, system of non-conversed heat removal by way of its radiation into environment with the devices for deployment of this system, automatic control system, system for cesium vapor supply to thermionic converters, vacuum degassing unit for vacuum treatment evacuation of reactor cesium cavities before beginning of PC operation and pump-down of gas impurities from these cavities during operation, and also cable network and load-carrying structures for fastening of PC constituent parts to support structures at Martian surface. Equipment of the reactor unit is sealed in pressurized container (vessel) filled with inert gas. The versions of radiation shield being considered for the PC in stationary embodiment includes application of shielding blocks delivered from the Earth as well as use of planet ground in the form of a dike around the reactor unit