Cell Characterization

 

• Cell technology/construction
• Boron-Oxygen complex / Light Induced Degradation
• Shunting due to metal migration across the p-n junction
• Electroluminescence
• Temperature Coefficient

A solar cell consists of a light-induced current source, a diode that generates a saturation current, series resistance, and shunt resistance. The series resistance is due to the resistance of the metal contacts, ohmic losses in the front surface of the cell, impurity concentrations, and junction depth. The series resistance is an important parameter because it reduces both the cell's shortcircuit current and its maximum power output. Ideally, the series resistance should be 0W (rs = 0). The shunt resistance represents the loss due to surface leakage along the edge of the cell or to crystal defects. Ideally, the shunt resistance should be infinite Efficiency of the solar cel is characterized by measuring the maximum power point (Pmax), the energy conversion efficiency (η), and the fill factor (FF).

 

When a PV cell is exposed to higher temperatures, Isc increases slightly, while Voc decreases more significantly. 

 

Electroluminescence is a non destructive photographic surveying method for the analysis of silicon solar cells and photovoltaic modules that provides data on related to uniformity of cell and modules, PV module damages are detectable such as microcracks, disruptions within the metal grid of the solar cell, shunts between base and emitter as well as disruptions of the electrical interconnectors