Insulation Resistance Tester For PV Systems (MIS-PV1) for the exclusive use in photovoltaic systems. The ordinary insulation resistance testers cannot make measurement properly during generation of PV systems. This instrument, however, can measure the insulation resistance simply by touching probe to the live line whether making generation or not. There are two ranges of PVH and PVL. PVH is for high voltage generation system (more than 500V and less than 1000V) and PVL is for the system less than 500V.