For reducing the manufacturing cost and for increasing the efficiency of module-integrated converter the transformerless concept is suitable. The new type inverter, which is proposed in this paper, basically works as buck boost DC-DC converter. Therefore, it is possible to reduce the number of the active switches in comparison with conventional inverter for AC modules because of simple circuit topology. In this paper authors present the control method and operation test results including both stand alone and grid connected for the new type transformerless inverter. These measurement results show that the performances can compete with the conventional small inverter (rated capacity around 50W). (C) 2001 Elsevier Science B.V. All rights reserved.