Elaborating on Ultraviolet Fluorescence for Field Inspection of Photovoltaic Modules

Offentlig prosjektsammendrag

In the past decade, the ultraviolet fluorescence (UVF) imaging method has been introduced to identify defects in wafer-based crystalline silicon photovoltaic modules such as for detection of cell cracks. However, this technique is mainly used in a lab environment under control environmental conditions for inspection in production lines. Therefore, this technique is not well explored for outdoor field inspection as several issues need to be solved such as difficulty to get high contrast images due to disturbance of ambient lighting and practical challenges in achieving long UVF exposure without threatening safety precaution. This research has the goal to elaborate on ultraviolet fluorescence for field inspection of photovoltaic modules and to analyze and qualify a UVF vision system for enabling outdoor aerial inspection. Solar energy installations are steadily increasing in the world also in Norway with ten thousands of modules installed on the roof every year. The raise of the solar energy business is constrained by two major needs (1) to drastically decrease the operations and maintenance costs in order to shorten the time for return of investment and (2) to perform inspection without sunlight (e.g. during night, in cloudy weather). Several companies are offering inspection services to reduce the manual inspection burden and costs using both thermal and visual imaging. This inspection can only be performed within sun hours while modules are activated through sunlight. In Nordic countries such as Norway, this inspection technique has limited time slots because of the restricted number of sun hours per year either due to short days e.g. winter period or cloudy weather in a large portion of the year. This research will combine a directional UV light beam and multiple exposure imaging to elaborate on high-contrast UVF imaging.