numerical analysis of zno thin layers having rough surface

In this paper an automated procedure for the analysis of Transparent Conductive Oxides (TCO) layers exhibiting rough surfaces is proposed. The method is based on the interaction between MATLAB and the Sentaurus TCAD and is aimed to the reduction of computational efforts needed for full three dimensional analyses. Experiments performed on CVD deposited ZnO layer, showing the reliability of the method for describing their optical properties, are reported. A semi-empirical technique for the extraction of the TCO refractive index is shown as well

Accurate Maximum Power Tracking in Photovoltaic Systems Affected by Partial Shading

A maximum power tracking algorithm exploiting operating point information gained on individual solar panels is presented. The proposed algorithm recognizes the presence of multiple local maxima in the power voltage curve of a shaded solar field and evaluates the coordinated of the absolute maximum. The effectiveness of the proposed approach is evidenced by means of circuit level simulation and experimental results. Experiments evidenced that, in comparison with a standard perturb and observe algorithm, we achieve faster convergence in normal operating conditions (when the solar field is uniformly illuminated) and we accurately locate the absolute maximum power point in partial shading conditions, thus avoiding the convergence on local maxima

Investigating the Impact of Cracks on Solar Cells Performance: Analysis based on Nonuniform and Uniform Crack Distributions

The paper investigates the detrimental effect of nonuniform and uniform crack distributions over a solar cell in terms of open-circuit voltage (V_oc), short-circuit current density (J_sc), and output power, the latter under a wide range of irradiance conditions. The experimental procedure to detect the cracks relies on electroluminescence imaging, which is nondestructive and requires a relatively low amount of time. The Griddler software is adopted to translate the EL-taken image into V_oc and J_sc maps. The main findings can be summarized as follows: (i) the nonuniformly- and uniformly-cracked cells are both jeopardized in terms of output power; (ii) the loss corresponding to the cell with nonuniform distribution of cracks is increasingly higher than the uniformly-cracked counterpart as the irradiance hitting the cells grows, and (iii) all cells affected by nonuniform cracks are severely damaged in terms of fingers and rear busbar, which concur to limit the maximum output current

Design of a Portable Low-Cost I-V Curve Tracer for On-Line and In Situ Inspection of PV Modules

Identifying underperforming photovoltaic (PV) modules is crucial to ensure optimal energy production and financial returns, as well as preventing potential safety hazards in case of severe damage. To this aim, current–voltage (I-V) curve tracing can be employed as in situ monitoring technique for the early detection of faults. In this paper, we introduce a novel low-cost, microcontroller-based I-V tracer for the diagnosis of individual PV modules. The tool features a unique power conditioning circuit, facilitating accurate data acquisition under static conditions as well as the even distribution of the measured points along the I-V curve. A specific active disconnecting circuit enables in situ and on-line measurement without interrupting the string power generation. The designed prototype is used to characterize a set of PV modules under real operating conditions. The measured I-V curves exhibit expected trends, with the measured data closely matching theoretical values and an estimated mean relative error less than 3%

On the Optimal Orientation of Bifacial Solar Modules

This paper presents an accurate simulation strategy to optimize the installation of bifacial photovoltaic modules in terms of orientation and tilt. The tool relies on horizontal irradiance data and ambient temperature taken from PVGIS for assigned times during the day at the selected geographical site and provides the I-V (and P-V) curves at each time. In this analysis, Naples is chosen as a case-study. It is shown that vertical bifacial modules with the front oriented either to West or to East offer energy production comparable to that of a South-oriented monofacial panel tilted by 30°, which represents the conventional optimized configuration and is thus considered as a reference

Progettazione e realizzazione di una struttura di test per la misura dei parametri di trasporto nei semiconduttori

Dottorato di ricerca in ingegneria elettronica e informatica. 8. ciclo. Tutore P. Spirito. Coordinatore L. CordellaConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal