Measurements of DC arc faults in real photovoltaic systems

Arc faults pose an extreme safety risk in already existing photovoltaic systems. In comparison to AC installations arc faults in photovoltaic systems have a significantly higher hazard potential. Missing zero-crossings of the current and the fact that a solar generator regarded as a source of energy cannot be switched off ensure much better conditions of existence for arc faults. The fundamental theoretical principles of DC arc faults in solar generators are described. In addition to that the main DC arc fault scenarios were classified in regards to their resulting risk for the whole photovoltaic system. Furthermore the special requirements of an arc generating unit for DC arc fault studies in real photovoltaic systems are characterized. The basic construction and use of a specifically designed arc fault generator for experimental investigations are described. In conclusion the first measurement results concerning the influence of arc faults on the source characteristic of the solar generator are presented.