In this paper a novel packed U cell (PUC) based multilevel grid connected inverter is proposed. Unlike the U cell arrangement which consists of two power switches and one capacitor, in the proposed converter topology a lower DC power supply from renewable energy resources such as photovoltaic arrays (PV) is used as a base power source. The proposed topology offers higher efficiency and lower cost using a small number of power switches and a lower DC power source which is supplied from renewable energy resources. Other capacitor voltages are extracted from the base lower DC power source using isolated DC-DC power converters. The operation principle of proposed transformerless multilevel grid connected inverter is analyzed theoretically. Operation of the proposed multilevel grid connected inverter is verified through simulation studies. An experimental prototype using STM32F407 discovery controller board is performed to verify the simulation results.Multilevel inverters are the most suitable solution for grid connection of renewable energy resources such as photovoltaic arrays (PV) or wind turbines. Multilevel inverters can produce high voltage with lower harmonics and lower stress on power switches 1 . The most common multilevel inverter topologies are cascaded H-bridge (CHB), neutral point clamped (NPC), and flying capacitors (FC) 2-4 . Packed U cells (PUC) are recent developed multilevel inverters with reduced number of capacitors and power devices [5][6][7][8][9][10] . The PUC topology needs only one high voltage DC power supply and the lower voltage levels are automatically generated with switching operation in packed U cell capacitors. However, the CHB inverter requires many DC power sources 11 . With equal number of voltage levels, the PUC inverter requires half of power supplies and one third of capacitors compared with FC topology 12 . Furthermore, in the PUC inverter the zero voltage level in freewheeling period can be achieved without using extra power switches. Therefore, the common mode voltage (CMV) will be zero in freewheeling period; as a result the ground leakage current will be declined significantly.In this paper a novel PUC based multilevel inverter is proposed. Unlike the PUC topology, a lower DC power supply from renewable energy resources such as photovoltaic arrays (PV) is used as a base power source. In fact, other power sources are extracted from the base lower DC power supply using isolated DC-DC power converters. In this case, the output peak voltage will be the summation of lower DC power supply and individual DC power sources extracted from the base power source via isolated DC-DC power converters. Moreover, the DC source voltages are the integer multiples of the lowest DC power supply. Therefore, in contrast with the PUC topology with a higher DC voltage source, in the proposed multilevel inverter, multiple low voltage DC power supplies are used.Moreover, only a lower DC source and multiple isolated push-pull or forward DC-DC converters can be used instead of a higher DC voltage supp...