Nowadays, there are several remote areas across the globe that rely on electricity grids of small scale (micro-grids), normally employing oil-fired power generation solutions of low energy quality at very high electricity production cost. At the same time, in many of these regions one may encounter significant solar potential that encourages installation of photovoltaic (PV) generators. However, due to the variable nature of solar energy, PV systems may be combined with appropriate energy storage systems (ESSs) in order to support either the energy autonomy of an area (e.g., an island) or to substitute the expensive operation of conventional power stations during predefined load demand periods. Based on this, this chapter is dedicated to investigating several commercially established or emerging ESS configurations that may interact with the primary renewable energy source (the sun) and provide a reliable and secure electric power supply into a remote island grid. In addition, special emphasis is given on the methodology applied for determining the optimum PV-ESS combination, based on several technical criteria and economic indexes. Finally, a representative case study is evaluated comprising a PV plant—able to satisfy a significant amount of the electricity demand of a remote small-island network—as well as an appropriate ESS facility that guarantees great levels of autonomy of the local community’s electricity requirements.