Conference article

HOMER software was used to technical and economically assess two renewable energy supply (RES) system configurations – PV-only (80 kW) and PV (34 kW)/WT (36 kW); both with a three day storage capacity and requiring 11kW of electric power – proposed by a partnership project responsible for the implementation of sustainable measures on a Portuguese small island. HOMER calculation showed insufficient storage capacity for both RES system proposed; so extra storage capacity should be added. Economically; life cycle cost (NPC) of the cheaper configuration (PV/WT) resulting from HOMER calculation was significantly lower (20%) than the one advanced by the project. On a second stage; HOMER was used to compute an optimal RES system configuration to attend water desalination and street lighting electric additional loads. The optimal configuration – PV (25 kW)/WT (18kW) – costs 18% less than the equivalent PV/WT system proposed by the project when the same additional load is considered. Sensitivity analysis on the electric load showed the cost difference between project’s and HOMER’s proposals fading as the load increased. Variation on wind speed average demonstrated the significance of data accuracy: using NASA’s average wind speed data the NPC increased on 15% compared to using wind speed values revealed on a monitoring campaign on the island.

Remote off-grid energy systems; Optimization software; Sensitivity analysis