The connection of renewable energy sources (RESs) to the distribution network (DN) has been rising at a steady pace over the past decades. The great penetration of RESs such as grid-connected photovoltaic system (GCPVS) brings new technical challenges to the DNs such as unintentional islanding. Conceptually, this situation occurs when a portion of the network that has been isolated from the main grid remains energized by the embedded RESs. This unexpected scenario should be thereby identified effectively to avoid frequency and voltage deviations and their hazardous effects. The aim of this paper is to provide a comprehensive review on the recently developed islanding detection methods (IDMs) for GCPVS, analyses their existing limitations, and suggests possible future research implementations. In this context, an in-depth comparison is provided considering the main features used in IDMs such as non-detection zone (NDZ), detection time, implementation cost and complexity, and power quality (PQ) degradation. Finally, the main technical requirements established by the current grid codes are recalled identifying potential multi-functional approaches to expand the current islanding detection capabilities.

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