Efficiency analysis of PV power plants shaded by MV overhead lines

This paper deals with the occurrence of hot spot phenomena in photovoltaic (PV) systems under partial shading caused by objects on some parts of the modules. An interesting case of diffuse shadows is determined by overhead distribution lines whose path crosses or are in the proximity of the PV power plants. Investigating the impact of these shadows on reducing the power production of PV or on damaging the PV modules as the modules’ temperature is increasing, is of high interest. At the SolarTech laboratory of Politecnico di Milano, the conditions for hot spot phenomena occurrence due to the overhead lines shading the PV cells were reproduced. Two experimental campaigns were carried out to investigate the current–voltage and power–voltage characteristics, and the energy production. In each experimental campaign, the built shading structure was considered fixed and different shading conditions were created based on the natural displacement of the sun. The hot spot phenomena was revealed on a field PV installation in Italy, caused my medium voltage overhead lines shading the PV cells, using infrared imagery

Smart Cities - The Optimization of their Development

The ongoing development and extensions of cities, as well as the requirement for large scale deployment of renewable energy sources and electro-mobility determine the transformation of current electrical grids towards smart grids. The increasing demand and the requirement for its reliable supply is imposing new planning challenges for the development of electrical networks. The present paper describes a method of optimizing the development of urban electricity networks, by selecting from a set of available locations, the positions and the size of new power sources, using a multistage model. Results can be useful to plan the installation of new power sources in an existing network (distributed sources, renewable sources for powering electric vehicles)

An Integrated Psycho-Sociological Perspective on Public Employees’ Motivation and Performance

In the context of profound social, economic and financial changes, private and public organizations managers turn their attention towards the most valuable resource they have – the human resource (HR), the one that can ensure increased organizational performance. Using adequate HR policies and practices, organizations can build a positive work environment that sustains employees’ development, encourages communication, innovation, and pro-active attitudes and behaviors. However, managerial practices specific to the private sector do not seem to be the solution to the problems public institutions deal with. While specialists have mainly explored the link between human resources management (HRM) and performance in the private sector, due consideration ought to be paid to the particularities of this relationship in the public sector as well, and to the factors that influence public employees’ motivation and determine their level of performance. The purpose of our paper is to show that HRM in public institutions should be approached in a manner that focuses more on the work motivation theory, specifically on the psycho-sociological profile of the public employee, and argue that higher performance can be achieved by establishing a social exchange relationship between managers and the members of their teams. A supportive work environment positively impacts upon public employees’ performance, self-efficacy and job satisfaction, even though they are mainly driven in performing their tasks by intrinsic motivators and devotion to public values and interest

Transient Analysis of Large Scale PV Systems with Floating DC Section

The increasing penetration of renewable sources with power-electronic interfaces in power systems is raising technical problems and the overall efficiency of photovoltaic systems can decrease dramatically. In this context, the optimal layout for the photovoltaic system is required. The most adequate strategy to connect the renewable system to the electrical power grid or to supply the end users must be adopted. The present paper proposes a design layout of a PV plant using a DC bus system to improve the overall energy conversion efficiency. An analysis of steady-state system stability, voltage drop and DC cable conduction losses is conducted. The leakage currents to the ground are investigated through simulations. Experimental results are shown focused on the analysis of optimal layout of photovoltaic systems under particular operating conditions

Snail Trails and Cell Microcrack Impact on PV Module Maximum Power and Energy Production

—This paper analyzes the impact of the snail trail phenomena on photovoltaic (PV) module performances and energy production. Several tests (visual inspection, maximum power determination, dielectric withstand, wet leakage current, and electroluminescence test) were carried out on 31 PV modules located in a PV plant in Italy. The electroluminescence test highlighted the strong correlation between the appearance of snail trails and presence of damaged cells in PV modules. The daily energy produced by four PV modules affected by snail trails ranged between 68% and 88% of the energy produced by a damage free commercial PV module over the same period

Is peer review in academic publishing still working?

Peer review is central to academic publishing. Yet for many it is a mysterious and contentious practice, which can cause distress for both reviewers, and those whose work is reviewed. This paper, produced by the Editors’ Collective, examines the past and future of peer review in academic publishing. The first sections consider how peer review has been defined and practised in changing academic contexts, and its educational significance in the development of scholarship. The paper then explores major historical and contemporary issues around identity, diversity, anonymity, and the review process, and the related power of editors versus reviewers in academic publishing. Finally, the paper discusses the case of new scholars as reviewers engaging in neoliberal labour, before concluding with some brief recommendations based on our analysis