Conventional insulation testers require a suitable adapter to short-circuit the positive and negative terminals of the PV string being tested due to the presence of string voltage. With the PV-ISOTEST, the use of an external device is not necessary. The PV-ISOTEST performs insulation measurements fully autonomously and independently. Furthermore, the PV-ISOTEST, using the new GFL function (Ground Fault Locator), also indicates the exact location of an insulation fault within a string of the PV system. Features: Insulation measurement up to 1,500 V DC even on live systems, localization of insulation faults in a PV string through the new GFL function, low-resistance measurement (protective conductor) with a test current over 200 mA, measurement of polarization index (PI) and dielectric absorption ratio (DAR), measurement of AC voltage components in the PV string.