Non-Destructive Measurement of Acetic Acid and Its Distribution in a Photovoltaic Module during Damp Heat Testing Using pH-Sensitive Fluorescent Dye Sensors

Abstract

An optical pH sensor that enables the non-destructive measurement of acetic acid and its distribution in a photovoltaic module during damp heat (DH) testing is reported. The sensor was fabricated by impregnating a solution of a pH-sensitive fluorescent dye into a fluororesin membrane filter, which was then dried. While conducting the DH test, fluorescence spectra from 20 pH sensors were periodically recorded and converted into pH values using a predetermined calibration curve. As a result, we succeeded in measuring changes in pH with a DH test time of up to 2000 h, and it was possible to obtain information on the pH distribution in the module. We also confirmed no change in pH in a module with a silicone encapsulant free from acetic acid, and revealed that the sensor that we developed does not respond to moisture and heat, but only to acetic acid.

Metal Hydrogen-Bonded Organic Framework as a pH Sensor for the Detection of Strong Acids

“…As an important indicator of material property, the pH value was widely applied in various fields such as chemical engineering, chemical kinetic mechanism, and chemical industry. − In the past decades, many methods had been studied for pH detection, ranging from low precision to high precision, such as pH meters and acid–base indicators. − The pH meters had been proved to be an effective approach for pH detection because of their convenience, excellent accuracy, and high efficiency. However, its development was limited due to high cost and vulnerability. − As for the acid–base indicator, it was utilized for the detection of pH by changing color in different acidic or alkaline solutions.…”

Recent Progress in Micro- and Nanotechnology-Enabled Sensors for Biomedical and Environmental Challenges

“…Beinert et al [ 192 ] proposed silicon solar-cell-integrated stress and temperature sensors for the direct and continuous in situ measurement of mechanical stress and temperature in photovoltaic (PV) modules, achieving sensitivities of ( )%/GPa for the stress sensor and ( ) for the temperature sensor, enabling increased measurement accuracy, process evaluation, reliability tests, and correlation with real exposure to climate in PV module research. Nagasaki et al [ 193 ] developed an optical pH sensor using a pH-sensitive fluorescent dye embedded in a fluororesin membrane filter, enabling the non-destructive measurement of acetic acid and its distribution in a photovoltaic module during damp heat (DH) testing. It successfully tracked pH changes for up to 2000 h and demonstrated a selective response to acetic acid without being influenced by moisture and heat.…”