7 research outputs found

    A Distributed Electrical Model for Interdigitated back Contact Silicon Solar Cells

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    AbstractIn this paper we introduce a quasi 3-D electrical model for a high efficiency interdigitated back contact (IBC) solar cell. This distributed electrical network is based on two-diodes circuit elementary units. It allows accounting for the resistive losses due to the transport through the emitter, the back surface field (BSF) and the fingers and busbars metallization. Moreover, it can model the electrical shading losses attributed to the BSF busbar. We calibrated the electrical components of the model according to experimental measurements on real devices. The validity of the model is demonstrated by the good agreement between simulation and experimental results for dark and illuminated IV measurements with and without masked busbars. The model can now easily be applied to simulate and optimize different metal grid layouts

    Secure communication protocol for wireless sensor networks

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    We propose a new communication protocol for wireless sensor networks, allowing to make them secure with respect to malicious attacks. Compared to standard secure protocols (e.g., the IEEE 802.15.4 and the ZigBee), the one we propose allows to increase security significantly, at negligible impact on node complexity. A possible hardware scheme to implement our protocol is also proposed

    Modelling and Design of Advanced Reliable Circuits and Devices for Energy Efficiency

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    Reliable electronic systems, namely a set of reliable electronic devices connected to each other and working correctly together for the same functionality, represent an essential ingredient for the large-scale commercial implementation of any technological advancement. Microelectronics technologies and new powerful integrated circuits provide noticeable improvements in performance and cost-effectiveness, and allow introducing electronic systems in increasingly diversified contexts. On the other hand, opening of new fields of application leads to new, unexplored reliability issues. The development of semiconductor device and electrical models (such as the well known SPICE models) able to describe the electrical behavior of devices and circuits, is a useful means to simulate and analyze the functionality of new electronic architectures and new technologies. Moreover, it represents an effective way to point out the reliability issues due to the employment of advanced electronic systems in new application contexts. In this thesis modeling and design of both advanced reliable circuits for general-purpose applications and devices for energy efficiency are considered. More in details, the following activities have been carried out: first, reliability issues in terms of security of standard communication protocols in wireless sensor networks are discussed. A new communication protocol is introduced, allows increasing the network security. Second, a novel scheme for the on-die measurement of either clock jitter or process parameter variations is proposed. The developed scheme can be used for an evaluation of both jitter and process parameter variations at low costs. Then, reliability issues in the field of “energy scavenging systems” have been analyzed. An accurate analysis and modeling of the effects of faults affecting circuit for energy harvesting from mechanical vibrations is performed. Finally, the problem of modeling the electrical and thermal behavior of photovoltaic (PV) cells under hot-spot condition is addressed with the development of an electrical and thermal model

    Model for thermal behavior of shaded PV cells under hot-spot condition

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    We address the problem of modeling the thermal behavior of photovoltaic (PV) cells that, due to their being exposed to shading, may experience a dramatic temperature increase (a phenomenon referred to as hot-spot) with consequent reduction of the provided power. Our proposed model has been validated against experimental data, and constitutes a first preliminary step towards the development of shading-tolerant approaches, while also highlighting a counterintuitive PV cell behavior useful to energy efficient PC array design

    Understanding the Influence of Busbars in Large-Area IBC Solar Cells by Distributed SPICE Simulations

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    In this paper we model a large-area high-efficiency interdigitated back-contact (IBC) solar cell by means of a distributed electrical network. The simulation tool allows accounting for the distributed resistive effects in diffusions and metallization. The model also considers the electrical shading effect and resistive losses due to both BSF and emitter busbars. A calibrated model is used to investigate the case of a large-area (15.6x15.6 cm2) IBC cell, in which we investigate the influence of key busbar parameters: number of busbars; busbar width; soldering pitch (for module connection); metal sheet resistance. The predictive simulations allow finding out the optimum number of busbars, arising from a tradeoff between the electrical shading effect due to the BSF busbars and resistive losses due to the emitter busbars and the fingers. Moreover, we show how the distance between soldering points on the metal busbars, influences the choice of the busbar width. We found out that, if an adequate number (>7) of soldering points is adopted, the busbar width should be kept lower than 0.5mm. On the other hand, the adoption of a thick Cu-plating (15ÎĽm) leads to an increase of efficiency of 0.2%abs with respect to the case of sputtered Al metal (3ÎĽm thick)

    Local Shunting in Multicrystalline Silicon Solar Cells: Distributed Electrical Simulations and Experiments

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    In this paper, we analyze the effect of local shunts in photovoltaic (PV) solar cells by experimental characterization and distributed electrical simulations. To this purpose, we developed a quasi-3-D distributed electrical network that is based on two-diode circuit elementary units. It allows accounting for resistive losses as- sociated to the transport through the emitter, the fingers and the busbars, and to local defects in the semiconductor. The electrical parameters of the equivalent circuit units are calibrated according to experiments performed on multicrystalline (mc-Si) silicon solar cells, including samples that feature local shunts due to localized defects, which lead to nonuniform distribution of electrical and optical properties. The distributed electrical simulations account for the degradation of fill factor and power conversion efficiency in case of local shunting. Moreover, by combining the proposed tool with a RC thermal network it is possible to estimate the tempera- ture distribution in a shunted solar cell. Our analysis shows how a shunted cell that operates under hot-spot conditions is subject to significant local overheating, which possibly lead to permanent PV cell damages

    A Blockchain-based Brokerage Platform for Fog Computing Resource Federation

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    This demonstration aims at showcasing an initial version of the DECENTER Brokerage Platform, which leverages an Ethereum blockchain to enable resource federation among different Fog Computing infrastructures. We consider a scenario where an Italian Infrastructure Provider wants to seamlessly extend its pool of resources to get access to an IP camera located in Korea, so that it can deploy an application to locally perform text recognition from a live video stream
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