It is an advantage for a renewable energy system to have an output signal suitable with standard applications. This situation is important in both compatibility and economical issues. This can be achieved by using battery packs and transformers. For modular applications the major problem in this area is large physical dimensions. In this study a high frequency multi-winding transformer is used to reduce the size of the system. In the output part a simplified multi-level inverter is used in order to decrease the number of switching elements. And calculation of switching angles for the multi-level inverter is handled by a simple control method.