322,989 research outputs found
Automatic edge identification for accurate analysis of thermographic images of solar panels
No full textThis paper proposes a segmentation method to analyze thermographic images of large solar fields with the aim to identify the borders of photovoltaic modules. This kind of analysis allows to correctly attribute possible faults, revealed by thermography, to a well specified solar panel. Moreover, the knowledge of the specific model of solar panel allows to bring the analysis to the single solar cell. This latter feature can help to eliminate some false positive that the mere observation of hot spots might produce
A Power MOS Based Circuit for Controlling the Hot Spot Temperature in Photovoltaic Modules
No full textLocalized overtemperature (hot spot) is universally recognized as the main cause of unexpected failure and reliability issues in photovoltaic plants. In fact, the hot spot temperature can be so high to permanently injury the solar panel. Right now, the only countermeasure adopted by solar panel manufacturers is to group solar cells in shorter strings, so that the allowed electrical power in each group is low enough to keep the overtemperature within safe limits. In this paper, a bypass circuit able of controlling power dissipation by modulating the current flowing through the affected solar cell, up to, if applicable, completely cancelling such current. This latter is deviated through a parallel bypass diode (as in standard solar panels), whose possible over heating is in turn prevented by the proper sharing of the current. The correct operation of the circuit is evidenced by means of experiments showing the capability to regulate the overtemperature from zero to the hot spot
Wireless Sensor for Monitoring of Individual PV Modules
No full textThe paper deals with a module-level monitoring and diagnostic system consisting in wireless self-powered sensors installed on individual PV modules and performing real-time measurements of operating voltage and current, open-circuit voltage, and short-circuit current. A disconnection system assures that the PV sensor does not affect the behavior of the string during the measurement phase and allows many benefits like the automatic detection of bypass events. An experimental campaign is performed to prove the reliability and usefulness of the sensor for monitoring of PV plants. The capability to detect faults and to accurately localize malfunctioning modules in a PV string is highlighted
A Measurement method of the ideal I-V characteristics of diodes up to the built-in voltage limit
No full textExperimental measurements of Majority and Minority Carrier Lifetime Profile in Si- epilayers by the use of an improved OCVD method
No full textIn this letter, the first experimental results of a recently proposed technique for measuring the carrier lifetime profile are presented. The technique makes use of a four-terminal bipolar test structure to electrically define the epilayer volume where recombination occurs and employs the open circuit voltage decay method for lifetime parameters extraction. For the capability of the test structure to depurate measurements from the parasitic ohmic effects, the technique is able to measure the ambipolar and minority carrier lifetime along epilayer at high and low injection levels respectively. Comparisons of measurements with numerical simulations are reported to confirm the validity of the proposed technique
Modelling and characterisation of the input I-V curves of bipolar JFET structures showing a negative resistance behaviour
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Modelling and characterisation of the input I-V curves of the Bipolar Jfet structures showing a negative Resistance behaviour
No full textModelling of the input I-V curves of bipolar JFET structures showing a negative resistance behaviour
No full textModelling of the input I-V curves of bipolar JFET structures showing a negative resistance behaviour
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