The Performance Assessment of Wave and Tidal Array Systems (PerAWaT) project, launched in October 2009 with £8m of ETI investment.The project delivered validated, commercial software tools capable of significantly reducing the levels of uncertainty associated with predicting the energy yield of major wave and tidal stream energy arrays. It also produced information that will help reduce commercial risk of future large scale wave and tidal array developments.Validation of the numerical models developed in TidalFarmer is essential in order to predict the expected energy yield with a quantifiable level of uncertainty. This will provide stakeholder confidence in the planning, investment and maintenance of a tidal array and will help accelerate growth of the tidal energy industry. The various numerical and experimental studies performed throughout the PerAWaT project can be used to form comparisons with the array-scale model to test whether it is an accurate representation of a tidal stream farm. In this work, it is assumed that each of these studies is comparable to the full-scale Tidal Generation Ltd device. As such, discussions relating to the accuracy of the studies to the full-scale device are provided throughout. In order to check the adequacy of the modelling assumptions and limitations of each model component, a comparison to experimental and numerical studies has been undertaken. In addition, an uncertainty analysis is provided whereby the impact of standard measurement uncertainty on the model outputs is discussed. Suggestions for further work, in order to decrease uncertainty in energy yield predictions, are provided.