The number of German PV installations reach in early 2013 1.4 million systems. On the basis of recent research which was carried out within a 3 year R&D-project of TÜV Rheinland with Fraunhofer ISE and several industry partners, around 75 cases were found where a PV system caused a fire through arc faults or hot spots. Out of these known incidents, 65 cases caused major damage whereas 10 faults lead to total loss of the system and building [1]. These numbers display that fire incidents caused by e.g. arc faults are a minority, but every case reveals that latent risks exist when defective installation or products are applied. This work focuses on the qualification of different arc noise spectra which displays a variety of characteristics depending on the electrode contacts, contact materials, implied PV solar simulator, PV array or whether the arc was ignited in a short circuit or being in series with a load resistor or even the inverter.