Single phase neutral point clamped (NPC) inverters are one of the most perspective types of Photo-Voltaic Inverters for single phase transformerless grid connected application. Source [2] mentions active clamped stacked neutral point inverter (ASNPC), which is one of the most advanced variations of NPC inverters – its power circuit consists of 8 transistors, with 8 antiparallel diodes. For the purpose of getting into a subject an earlier version of NPC inverter was used – active neutral point inverter (ANPC), which consists of 6 transistor-diode switches. ANPC inverter was tested together with control strategy, that gives natural doubling of the apparent commutation frequency. Sigma-delta modulation technique usage is also considered.