Different control structures for single-phase PV systems are described and the blocks involved are described in detail. The issue of synchronizing is firstly addressed and different techniques like PLL and filtering are addressed.

Then the quality of the current controller is emphasized as

a key issue in order to ensure stability and compliance with the new stringent power quality standards like IEE 929. Both classical PI control and new P+Resonant control yielding better performacies and harmonic compensation is discussed. Next, different structures of MPPT are described and practical implementation and obtained performances are shown.Finally, the need of anti-islanding feature is explained as a safety measure for grid-connected PV inverters. The classical solution involves extra hardware. The new trend is to use software anti-island methods which need only some extra functions implemented in the existing DSP and no extra hardware. Practical implementation of an original method using non-characteristic harmonic injection is presented.