Islands are highly diverse in their climatic, physical, social, and economic characteristics. Thus, each island’s energy system needs to be designed according to its specific features. However, similarities among islands exist which can enable the fast transfer of concepts and experiences with energy systems. In the Philippines, only few off-grid islands are incorporating smart energy systems through hybrid electricity systems. While most off-grid islands still do not have access to electricity, the majority of off-grid Philippine islands having access to electricity are powered primarily by diesel-fired generators. In this work, a cluster analysis is performed for 502 off-grid islands in the Philippine archipelago, classifying the islands according to their similarities in socio-economic and physical characteristics, and indigenous energy resource potential. The results show that most of the islands belong to five clusters of very small and small islands for which photovoltaic-battery systems would be the favourable backbone of a future energy system based on renewable energies. These islands show a varying level of feasibility for harnessing wind energy. In medium and big islands, opportunities of linking electricity systems to water supply and thermal energy loads as well as to the transport sector, are identified and their relevance in the clusters is discussed. The results are consistent with the validation of the individual characteristics of chosen off-grid islands. The cluster analysis results support policy makers and private investors in deciding which smart energy system projects are suitable for which particular islands.