A wave-structure interaction model is implemented, and power output estimates are made for a simplified wave energy converter operating in measured spectral wave conditions. In order to estimate power output from a wave energy converter, device response to hydrodynamic forces is computed using a boundary element method potential flow model. A method is outlined for using the hydrodynamic response to estimate power output. This method is demonstrated by considering an idealized non-resonating wave energy converter with one year of measured spectral wave conditions from the Oregon coast. The power calculation is performed in the frequency domain assuming a passive tuning system which is tuned at time scales ranging from hourly to annually. It is found that there is only a 3% gain in productivity by tuning hourly over tuning annually, suggesting that for a non-resonating wave energy converter, power output is not very sensitive to the value of the power take off damping. Interaction between wave energy converters in arrays is also considered, and results for an array of idealized point absorbers suggests that interactions are minimal when devices are placed 10 diameters apart from each other.