An efficiency comparative analysis of isolated multi-source grid-connected PV generation systems based on a HF-link micro-inverter approach

For solar photovoltaic grid-connected generation systems, four inverter configurations are currently available in the market for different power ranges of the required system. However, a power gap exists within the lower range of the commercial power scale, particularly between micro-inverters and string inverters, leaving room for innovation and development of flexible and modular converters in this power range. This paper presents three different isolated multi-source grid-connected PV generation systems based on a single-phase high-frequency link micro-inverter scheme, to evaluate the feasibility for reducing the mentioned power gap by using higher power density systems based on a micro-inverter approach instead of derating the currently available string inverters, which are optimized for higher input voltage and power conditions compared with micro-inverters. Losses estimations, peak and weighted efficiencies are presented for Multiple-Input Multiple-Output, Multiple-Input Single-Output and Single-Input Single-Output generation systems with different number of input power sources. Analysis and discussion for each system are presented, showing that a Multiple-Input Single-Output system scheme presents a feasible alternative to a higher power density converter, reducing the inverter market power gap, with attractive features for renewable energy sources such as modularity and flexibility.