Electrical performances optimization of Photovoltaic Modules with FMECA approach

摘要

The renewable energy industry has been growing remarkably over the last years and the recent Fukushima nuclear crisis has given a further incentive worldwide. In this context, solar radiation represents one of the most accessible energy resources and the involved industry has seen rapid expansion in the past decade with an ever-increasing share of the electricity-generating capacity. To this aim, both for manufactures and Photovoltaic Plant (PV) management, the assessment of the quality, reliability and electrical performances of their products are becoming more and more important. So, in order to fulfill such requirements, a Failure Modes, Effects and Criticality Analysis methodology (FMECA) has been proposed with the aim to classify the occurrence, the severity and the impact of all possible failure mechanisms on the PV module, which is the fundamental sub-system of the plant. The aim of the proposed approach is to reduce, or eliminate, the impact of potential failure modes before failures occur in the field and it highlights the final effects that show the occurrence of a fault or malfunction. Starting from the results of FMECA, it is also possible to implement suitable architecture of a monitoring system and its metrological characteristics, that can be applied in architecture devoted to Condition Monitoring (CM) techniques. By means of FMECA some crucial aspects for the efficiency of PV module have been put in evidence. Among these, the paper focuses the attention on the presence of pollution and dust on the panel surface. Such phenomenon, in fact, leads to a decrease of the transmittance of solar cell glazing and causes a significant degradation of solar conversion efficiency of PV modules. After the FMECA implementation two different steps has been followed. First the application of FMECA results has been verifies by means of a correlation between the energy reduction and the Maximum Power Point (MPP) of the PV module. Then, a sensitivity evaluation of MPP in function of the powder concentration has been analyzed and discussed. The sensitivity analysis has required the definition of a devoted experimental set-up able to guarantee the repeatability of the analysis; in fact, powder concentration analysis requires acquiring data in different time distant. FMECA approach results allow optimizing the electrical performances of the Photovoltaic Module and plant too.