On the numerous small and medium-sized Greek islands one may encounter several thousands of remote consumers unable to appreciate a direct electricity utility supply. For this purpose, remote consumers usually cover their electricity needs based on the operation of small diesel-generator sets. On the other hand, most of these areas appreciate high quality solar potential that comprises a stimulus for the use of stand-alone photovoltaic (PV)-based configurations. In this context, the primary objective of the present study is to determine the optimum dimensions of a stand-alone PV-diesel system, under the restriction of minimum long-term electricity generation cost, and accordingly obtain a comparison with diesel-only systems. For this purpose, the developed methodology is applied to a representative Greek island, with results obtained being rather encouraging for the implementation of the proposed solution.