A Solar AC Module with active filter capabilities

Small photo-Voltaic generators for residential applications are rapidly spreading all over the world in an effort to reduce polluting emissions. In this kind of applications the AC solar module concept has recently proven to be more advantageous than the conventional string architecture. According to the AC solar module concept, single PV modules are directly connected to the AC grid through a DC/DC converter and an inverter. However, in this case a periodical power unbalance is generated because the power drawn by a single-phase residential grid features a large ripple at twice the fundamental frequency, while PV modules generate a DC power. Such a power unbalance affects the Maximum Power Point Tracking and forces the system to operate under suboptimal conditions and is faced with the introduction of bulky electrolytic capacitors. In this paper a alternative approach is presented enabling a standard DC/DC converter to also act as a power ripple damper, without the introduction of extra power devices. A hybrid PWM/unfolder approach has been also developed to reduce the switching power losses of the inverter connecting the DC/DC converter to the grid.