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8th World Conference on Photovoltaic Energy Conversion; 585-593, In this paper, performance losses and correlated degradation of five different PV systems representing five different PV technologies are investigated. Here, we describe the overall performance loss of a PV system in greater detail to better understand which underlying reasons trigger the performance decline of the investigated PV systems. The plants were installed in 2010, and almost 12 years of system operation are considered. Based on best practices developed by the IEA PVPS Task 13, the linear performance loss rates of all PV systems have been calculated. The results are correlated with corresponding nonlinear performance losses, voltage and current evolution, I-V curves and infrared and luminescence images captured in the field. Overall, it was shown that crystalline-based PV systems experience a lower overall performance loss compared to thin-film systems. The losses in crystalline systems stem from cell mismatches within modules and gradually developing degradation modes such as snail trails and cell cracking. The thin-film systems under investigation are subject to higher performance loss rates, (most) likely triggered by a degradation of the active PV material. Furthermore, glass-glass thin-film modules are additionally exposed to physical stresses by the mounting clamps leading to cracked glass, which may jeopardize the mechanical integrity of the modules.

8th World Conference on Photovoltaic Energy Conversion; 1112-1118, Electroluminescence imaging experienced uprising use in the last years. In future photovoltaic plants the time-consuming connection of power supplies to photovoltaic module strings could be overcome by use of inverters with bi-directional functionality, allowing backpowering of connected module strings directly. During backpowering, the limits of the power supply must be considered. As temperature influences the open-circuit voltage, it is a crucial parameter to remain in these limits. The EL inspection itself impacts the solar cells temperature, as they warm up during the process, resulting in a shift of open circuit voltage. This work investigates the heating of a hetero junction photovoltaic module during electroluminescence inspection. The saturation temperature is estimated by energy balance calculations and experimentally verified to be around 20°C, with resulting voltage drop above 2 V. The importance of this is not only to verify that the measurement is within the limits of the power supply but also to consider changes of the recorded luminescence intensity due to the temperature, shown to have a decrease of up to 4 %.

38th European Photovoltaic Solar Energy Conference and Exhibition; 1042-1050, Procurement, installation and operation are different phases of a photovoltaic (PV) plant life cycle. Each of these phases come with different risks. These risks and their possible effects are shown in this paper with particular focus on PV modules, explained along the real construction of a PV plant in northern Italy. The quality is tested during all phases; before procurement to ensure module quality, after transport and installation to detect the impact of wrong handling, and during the operational phase. Electroluminescence, current-voltage curve measurements, infrared thermography and daylight photoluminescence were performed. Electroluminescence and current-voltage curve measurements were carried out during procurement and after transport and installation to evaluate the impact of module mishandling. The damage wrong handling of a PV module can cause is shown. During the first year of operation, two infrared thermography inspections were performed to assess the health status of the PV plant and to detect possible further degradation modes, which have not been noticed before. The development of hot spots over half a year is analyzed and severe cell cracks were found as root causes, detected through daylight photoluminescence imagery. Further, the applicability of daylight photoluminescence and the detectability of degradation modes in images of two varying distances is investigated.

37th European Photovoltaic Solar Energy Conference and Exhibition; 908-913, Daylight Photoluminescence (dPL) is a relatively novel imaging technique using the principle idea of photoluminescence with the sun as excitation source. The difficult process of filtering the luminescence signal is described by means of implementing a dPL technique at EURAC Research in Bolzano, Italy. The described approach uses modern inverter or maximum power point tracker to alter the working point of modules, which allows imaging of two different images, whose subtraction results in the luminescence signal. Further, the impact of temperature on the luminescence signal is investigated. For this, the signal intensity is measured with dPL for different temperatures under controlled conditions. The impact that temperature has on different factors influencing the luminescence intensity is described. Finally, the impact of temperature on dPL in practical use is calculated from the results, presenting a first attempt to calculate the temperature coefficient of signal intensity in the dPL image.

37th European Photovoltaic Solar Energy Conference and Exhibition; 1378-1380, In this work we present the ongoing PV4.0 project, which aims to develop a cost-effective PV plant monitoring and intervention system. By linking PV plant measurement data to a digital ticketing and asset management system, and additionally including the recently developed Cost-Priority-Number method [1], a tool will be developed that applies the concepts of Industry 4.0 to the PV sector. The developed tool aims to improve O&M by prioritizing maintenance activities, and streamlining and further digitalizing the workflow of technicians. Fault detection algorithms are developed based on machine learning approaches like clustering and outlier detection to automatically detect and classify anomalies in PV system output and consequently create maintenance tickets that specify a further course of action. By applying automatic failure detection, the aim is to decrease the time required for failure detection and intervention, in order to minimize revenue losses. By analysing historical and real-time PV plant data and historical failures in operation, the potential for predictive monitoring will be investigated. The digital tools will furthermore produce valuable statistics on PV plant failure modes within each analysed PV plant, and for PV plants in general.

Radiotherapy with nuclear reactor fission neutrons was applied in 49 cases of pretreated patients with superficial metastases or relapses from primary carcinoma. Measurements of the decay rates of the radiation-induced radioactivity of 49Ca, 38Cl and 24Na in the irradiated tissue resulted in values for the simultaneous local kinetics of chlorine and sodium, and in approximate data on the electrolyte masses. The electrolytes were present in non-exchangeable and exchangeable compartments of soft tissue. Exchange times of the intravascular to extravascular turnover and the frequencies of the exchange fractions were determined for a series of irradiations. The results have been interpreted in terms of the mean electrolyte exchange rates, of a standardized functional blood flow, and of the supply capacity of the vascular system. In the average of all cases, the regional perfusion was reduced by about 30% by irradiation up to 14 Gy (equivalent photon dose = 45 Gy) connected with an increase in the non-exchangeable fractions. After fractionated doses higher than 14 Gy, functional blood flow and supply capacity increased to 120%, and fixed electrolytes were removed from the irradiated tissue. Data on electrolyte kinetics and vascularity are compared with the literature.