The measurement and calculation of the I-V curve (current – voltage), of the module or of the string, allows to identify the short-circuit current and the no-load voltage. I-V curves can be performed with sunlight or at night (Dark I-V) by appropriately feeding the strings and therefore independently of the weather conditions, temperature and irradiation.

The detection of the I-V curve and the consequent calculation of the equivalent resistances can give very useful indications to identify problems of:

1) Short circuited bypass diodes
2) Glass corrosion
3) Delamination
4) Module degradation
5) PID (Polarization Induced Degradation)
6) LID (Light Induced Degradation) for Crystalline modules
7) Short circuited cells
8) Broken cells

Electroluminescence (EL) is photography (in the dark, with a camera equipped with a high-pass filter LWP) of the weak emission caused by the passage of reverse current through the cells of a photovoltaic module.

Until a few years ago, this type of analysis was the prerogative of a few specialized laboratories where the test could only be performed on a limited number of modules that had to be disassembled, packaged and adequately shipped with obvious repercussions in terms of time and costs. Today, our technicians perform EL Outdoor analysis, or directly in the field.

Through the analysis of an EL Outdoor image it is possible to identify all the cell cracks in the photovoltaic modules but also:

1) Defective bypass diodes (or short circuited) inside the junction box of the modules
2) Micro-cell fractures
3) PID (Potential Induced Degradation) of the cells
4) Frontal electrical contact problems of the cells
5) Failure to match cells and/or modules on the system