Determining MPPT and anti-islanding techniques in a grid-tie PV inverter

Numerous methods are known for grid-tie photovoltaic inverters to track the maximum power point and to avoid islanding operation, but the inverter manufacturers generally do not publish which of these methods they have implemented in their products. This paper reviews the most common maximum power point tracking and anti-islanding methods and points out to power quality signatures they may leave in the voltage and current waveforms on both the AC and DC sides of the inverter. Armed with this information, input and output waveforms of a commercial 2 kW grid-tie PV system are examined in an effort to identify which MMPT and active anti-islanding techniques are embedded in the inverter. The inverter response to different levels of over voltages is also reported.