To add more flexibility to the string inverter and improve the MPPT performance of the PV system, the multistring concept was developed. The strings are divided into smaller pieces (fewer modules in series) and connected through independent MPPT dc–dc converters to the grid-tied inverter. The dc–dc stage also boosts the voltage of the smaller strings. The additional dc–dc stages are a costeffective solution compared to having several string inverters. As can be seen in Figure 3, multistring inverters can also be found with or without isolation. Since they reduce partial shading and mismatching, they are suitable not only for rooftop PV systems but also for medium and large-scale plants.