IR Thermography in Condition Monitoring of PV Modules?
The overall efficiency of a photovoltaic (PV) system is strongly affected by specific degradation modes and defects that may occur during the lifetime of a PV module. These “faults” can be identified by applying responsible condition monitoring (CM) and diagnostic methods. Today, conventional CM of installed, operating PV modules, is mainly based on electrical measurements and performance evaluation. However, such practices exhibit restricted fault-detection ability. On the other hand, temperature-based CM methods, such as infrared (IR) thermography, are able to extract the “signature” of a potential fault by the thermal image pattern of an operating PV module. Read the Full Article »
A Tool for the Detection of Hot Spots in PV modules
The experimentation of the intended approach includes several daily sets of in-situ thermography measurements of specific PV arrays, installed on the rooftop of a laboratory building in the School of Engineering Campus of Democritus University of Thrace (DUTh), Greece. Further processing of the obtained thermal images, by means of a basic image histogram and line profile analysis, provides useful data for the detection and quantification of hot spots within each PV module. In particular, specific variations in the morphological features of both thermal images’ histograms and linear profiles witness the presence of defects, their source within the module and, ultimately, their impact on the degradation of the inspected PV array’s performance due to the hot-spot heating effect. Read the Full Article »
Accelerated Ageing Tests of c-Si PV modules
The idea and impetus for this research was brought by a basic question: If we are able to detect and diagnose faults in a c-Si PV module, using basically IR thermography, are we also able to prognose their evolution through time and, consequently, their impact to the module's efficiency? For this scope, we performed specific accelerated ageing tests to 3 monocrystalline-Si PV modules (with known defects in one of them) in cooperation with the School of Chemical Engineering, of the National Technical University of Athens (NTUA), and particularly with the Department of Materials Science and Engineering (headed by Professor A. Moropoulou). The ageing tests included 200 thermal cycles; the electrical performance of both the defective module and the "healthy" ones was measured at the start, in the middle and at the end of the ageing process. At the same stages of the whole process, numerous IR thermographic measurements were conducted to provide the thermal images of the modules and, hopefully, the evolution of the defects' thermal signatures, through the ageing. The first results of this project appear to be fairly promising.Detailed results and Full Article, are coming soon »
Tool Condition Monitoring in Machining Operations
The main scope of this paper is to present a summary of the monitoring methods, signal analysis and diagnostic techniques for tool wear and failure monitoring that have been proposed, tested or reported in literature up today, for unmanned machining operations. Initially, the necessity for planned tool condition monitoring in modern manufacturing is being discussed. Then, there is a discussion about the difference between soft and hard faults and the reason that they are used for prediction and diagnosis respectively. The paper, then, lists the basic parameters that are correlated with each type of fault. Both direct methods, such as computer vision, and indirect methods, such as vibration, that have been used to monitor the aforementioned parameters, are presented. Moreover, the paper summarizes the signal processing techniques that have been applied to each monitoring method, including e.g. statistical parameters and Wavelet Transform. Following this, a number of diagnostic tools, which have been developed for diagnosis of tool condition, are presented. Read the Full Article »
MeDiLab© - Innovation Corner
From time to time, MeDiLab© presents projects that are new, involve an inventive step, and are susceptible of industrial application. These creations are officially certified by The National Industrial Property Organization as innovations. This "innovation corner" includes an industrial hinge with four degrees of freedom, a method for production of deionized water, an intelligent ultrasonic device for level measurements, a rolling bearing strain unit and a car cover for hail protection applications, all briefly presented. Link to the related Web Page »