Nowadays there are various national and international regulations that are limiting the usage of fossil fuels for energy production [1]. This inspired the increase of demand for use of renewable energy sources. New technological advances in the field of power electronics made the application of renewable energy systems more reliable and efficient, which increased the demand of installing such systems. Nowadays it is even possible to generate energy from renewable energy sources in households by installing solar panels on roofs of houses, or by installing small wind generators [2]. However, there is one disadvantage of renewable energy sources – the energy is generated intermittently and energy production pattern does not match energy consumption pattern. Taking into account this drawback it is reasonable to use Battery Energy Storage Systems (BESSs) which allow to compensate the difference between production and consumption, and also increases the stability of the electrical grid since BESSs can also be used as uninterruptible power supplies. This paper deals with the description of multilevel converters with independent sources combined with unfolding circuit and non-inverting buck-boost converters for source voltage regulation.