An electric power conversion system for converting dc electric power from a plurality of unstable dc sources (100, 100', 100", 100a - 100d) to ac power for injection into an electric power grid, the electric power conversion system comprising: a plurality of unstable dc sources (100, 100', 100", 100a - 100d); a plurality of regulated current source inverters (11, 11',11", 11a-11d) each one of the plurality of regulated current source inverters having a plurality of switching devices (SW-1 - SW6; SW1' - SW6'; SW1" - SW6"') for producing a multiple phase ac output, the multiple phase ac output of each one of the plurality of regulated current source inverters operating synchronously with the voltages of the electric power grid, the commutation of the plurality of switching devices (SW-1 - SW6; SW1' - SW6'; SW1" - SW6"') in each one of the plurality of regulated current source inverters sequenced to produce multiple phase ac output currents from each one of the plurality of regulated current source inverters; at least one transformer (70; 72; 74; 76a, 76b; 78; 80a, 80b; 82; 84a, 84b) for phase shifting the multiple phase ac output currents from all of the plurality of regulated current source inverters for producing three phase current for injection into the electric power grid, the three phase currents having a multi-step waveform, whereby increasing the number of the plurality of regulated current source inverters decreases the total harmonic distortion of the multi-step waveform; the plurality of unstable dc source (100, 100', 100", 100a- 110d) being interconnected in parallel and supplying input power to each one of the plurality of regulated current source inverters (11, 11',11", 11a-11d), each of the plurality of regulated current source inverters comprising the combination of a step-up and step down dc current regulator to regulate the multiple phase ac output currents from each one of the plurality of regulated current source inverters at the maximum power point of the plurality of unstable dc sources interconnected in parallel and supplying power to each one of the plurality of regulated current source inverters independent of the instantaneous current output level from each one of the plurality of unstable dc sources supplying power to each one of the plurality of regulated current source inverters, the dc current regulator comprising a single pulse or a multiple pulse regulation in each regulation period. a plurality of unstable dc sources (100, 100', 100", 100a - 100d); a plurality of regulated current source inverters (11, 11',11", 11a-11d) each one of the plurality of regulated current source inverters having a plurality of switching devices (SW-1 - SW6; SW1' - SW6'; SW1" - SW6"') for producing a multiple phase ac output, the multiple phase ac output of each one of the plurality of regulated current source inverters operating synchronously with the voltages of the electric power grid, the commutation of the plurality of switching devices (SW-1 - SW6; SW1' - SW6'; SW1" - SW6"') in each one of the plurality of regulated current source inverters sequenced to produce multiple phase ac output currents from each one of the plurality of regulated current source inverters; at least one transformer (70; 72; 74; 76a, 76b; 78; 80a, 80b; 82; 84a, 84b) for phase shifting the multiple phase ac output currents from all of the plurality of regulated current source inverters for producing three phase current for injection into the electric power grid, the three phase currents having a multi-step waveform, whereby increasing the number of the plurality of regulated current source inverters decreases the total harmonic distortion of the multi-step waveform; the plurality of unstable dc source (100, 100', 100", 100a- 110d) being interconnected in parallel and supplying input power to each one of the plurality of regulated current source inverters (11, 11',11", 11a-11d), each of the plurality of regulated current source inverters comprising the combination of a step-up and step down dc current regulator to regulate the multiple phase ac output currents from each one of the plurality of regulated current source inverters at the maximum power point of the plurality of unstable dc sources interconnected in parallel and supplying power to each one of the plurality of regulated current source inverters independent of the instantaneous current output level from each one of the plurality of unstable dc sources supplying power to each one of the plurality of regulated current source inverters, the dc current regulator comprising a single pulse or a multiple pulse regulation in each regulation period.