This paper describes the technical and economic methods used to select a wind-diesel power system in the Canary Islands. The project was implemented with the aim of meeting the complete energy requirements of a small isolated fishing village, while minimizing fuel consumption and CO2 emissions. We focus on the decisions taken and lessons learned during configuration of the hybrid system. The project offers a working model for the application of renewable energy to an isolated community where there is no external electricity supply. We analyse nine hypotheses for the system's configuration and operation including the option of using diesel only as a base for comparison. Our results show that the hybrid systems, though employing high percentages of wind energy, were actually more expensive in terms of units of energy produced than the diesel only option, Therefore, a reduction in CO2 emissions implies additional costs in the energy supply system.