It is common in quasi-steady-state models of renewable power systems to use a 1 h time step despite the variability of the load and renewable sources within the hour. The purpose of this study was to examine the efficacy of this level of temporal resolution for a model that includes variable residential loads, wind, solar, diesel generator, and batteries. The component models were analyzed individually and as a complete system to develop an understanding of how each is affected by the temporal resolution. With higher resolution, the wind energy output and the fuel consumption of the genset increased. The PV and battery simulations were unaffected by temporal resolution. Agreement between optimization results was found to greatly depend on system configuration. Systems with only diesel for backup were found to increase in cost with higher temporal resolution. Those with battery backup were much less affected by the time step. For systems with both diesel and battery backup, the optimal system costs were fairly close but the optimal component sizes differed. Because of the many factors that affect the results of these systems, it is not yet possible to determine a general recommendation for choosing a time step prior to a simulation. (C) 2011 Elsevier Ltd. All rights reserved.