Water reflection analysis of encapsulated photovoltaic modules
AssigneeThe Regents of the University of California
InventorsDavid Fenning, Rishi Kumar, Guillaume von Gastrow
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Abstract
A method for moisture testing of a fully assembled photovoltaic (PV) module. An assembled PV module is probed with short wave IR probe energy in the range of 1700-2000 nm. Energy reflected from the assembled PV module is collected and directed to a sensor. Noise is removed from a signal of the sensor with reference to the probe energy. Absorption is of the probe energy is determined. The absorption is correlated to moisture in the PV module. A preferred system that carries out the method provides a signal-to-noise ratio (as defined by standard deviation/mean of measured reflectance) of at least 3800.
Claims14
A method for moisture testing of a fully assembled photovoltaic (PV) module, comprising:
- probing the assembled PV module with pulsed short wave IR probe energy in the range of 1700-2000 nm, wherein the short wave IR probe energy is pulsed according to a reference signal;
- collecting energy reflected from the assembled PV module and directing the energy to a sensor;
- integrating a reflectance signal from the sensor with the reference signal over a time period sufficient to average out signals out of phase with the reference signal and provide an absorption signal;
- analyzing the absorption signal to determine the presence or absence of moisture.
A system for moisture testing of a fully assembled photovoltaic (PV) module, comprising:
- a function generator for generate a pulsed reference signal;
- a pulsed light source responsive to the pulsed reference signal to emit probe energy in the range of 1700-2000 nm;
- optics to direct the probe energy upon the assembled PV module;
- optics to collect reflected energy from the assembled PV module;
- a sensor receiving collected reflected energy and generating a reflectance signal;
- a lock-in amplifier locked to the pulsed reference signal to attenuate noise in the collected reflected energy by integrating the reflectance signal with the reference signal over a time period sufficient to average out signals out of phase with the reference signal to provide an absorption signal;
- and
- electronic analysis of the absorption signal to determine whether moisture is indicated by the absorption signal.
Dependencies are inferred from the claim text.