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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%. [ABSTRACT FROM AUTHOR]

The paper deals with a grid-connected single-phase battery charger integrated with photovoltaic generators (PVGs). The circuit topology consists of a multilevel architecture based on a Cascaded H-Bridge (CHB) rectifier. Its main task is to charge the batteries, primarily from the PVGs, by also assuring to keep their state-of-charge (SOC) balanced. Nevertheless, when the battery SOC overcomes a predefined upper limit, beyond which the charging process could be interrupted, the available PV power can no longer be transferred to the batteries. Therefore, to avoid an undesired curtailment of PV power production, this latter can be supplied to the grid by inverting the system operation. The paper shows how to achieve this result by implementing a dedicated control action based on a multi-step procedure. Numerical investigations are carried out on a 19-level CHB converter implemented in the PLECS environment to validate the feasibility and effectiveness of the proposed control technique. [ABSTRACT FROM AUTHOR]

The aim of this work is to investigate the degradation of perovskite solar cells (PSCs) by means of impedance spectroscopy, a highly sensitive characterization technique used to establish the electrical response of a device in a nondestructive manner. In this paper, PSCs with two different electron transport layers (ETLs) are studied: PSCs with undoped SnO2 as an ETL are compared to PSCs with an ETL composed of graphene-doped SnO2 (G-SnO2). Experimental data were collected immediately after fabrication and after one week, monitoring both impedance spectroscopy and dark current-voltage (I-V) curves. It was observed that, in the case of the undoped PSCs, the degradation of the solar cells affected both the AC behavior of the devices, modifying the associated Nyquist plots, and the DC behavior, observable from the dark I-V measurements. Conversely, the solar cells with G-SnO2 showed no variation. Considering the Nyquist plots, a quantitative analysis was performed by comparing the parameters of a proper equivalent circuit model. The results were coherent with those achieved in the DC analysis, thus proving that the analysis of impedance spectra, supported with dark I-V curves, allows one to gain a deeper knowledge of the degradation phenomena of perovskite solar cells. This study opens the door for further improvement of these devices through a better understanding of their electrical behavior. [ABSTRACT FROM AUTHOR]

The aim of this paper is to perform an experimental investigation on the effects of electron beam irradiation on the recombination lifetime of both p-type and n-type silicon layers in order to provide a set of parameters useful to model the recombination effects in semiconductor computer simulation package. To this goal, we propose to use a proper three-terminal test structure in order to extract these parameters directly from lifetime measurements along the silicon layers at different temperatures and at different injection levels by using the same silicon samples before and after the electron irradiation process in order to highlight the effects of the irradiation itself on the lifetime. The experimental results indicate that the electron irradiation is more effective for controlling the high-injection lifetime in p-type silicon than in an n-type one. The effect of the irradiation on lifetime can be basically taken into account by means of one energy level placed at 0.27 eV below the conduction band edge for both n-type and p-type material, with [[Sigma].sub.p] [approximately equal to] 10[[Sigma].sub.n]. Index Terms - Charge carrier lifetime, radiation effects, semiconductor device modeling.

The majority carriers of a lateral current flow in a semiconductor test structure are responsible for the two-dimensional effects produced at the high injection condition. The debiasing of the injected electrode affects the lifetime profile measurements of the test structure. An analysis of the debiasing effect leads to some rules that can reduce the errors in the lifetime profile measurements. Fabrication of a test structure on n-type and p-type silicon epitaxial layers helps to determine the energy level of the recombination center present in the test structure.

An approximate closed-form solution for the transport equations in heavily doped regions is proposed, leading to an expression for the minority carrier currents, in which the influence of technological parameters is easily readable. The solution proposed is as accurate as the Bisschop series and has the advantage of improved computational efficiency.