Protection unit. If the combiner unit does not include a dc isolator, this must be provided separately and be easily accessible. Since a PV array always produces a voltage in sunlight it must be possible to disconnect it from the inverter for maintenance or testing. The isolate switch is rated for the maximum DC voltage and current of the array. Other safety features, including earthing, vary from country to country and between continents, although regulations are tending to harmonise as the PV industry extends its global reach