This paper presents a complete power loss model for an Archimedes screw used for power generation (ASG) including a non-dimensional model to predict power losses due to outlet submersion flooding. This model amends a prior idealized, frictionless ASG performance model to include power losses due to bearing friction, outlet exit effects, internal hydraulic friction and outlet submersion. This study presents data and a derived relationship for power losses due to outlet submergence and found that unmodified Manning's coefficients can be used to model internal fluid friction losses. Laboratory experiments on a scale-model ASG were conducted to determine variable relationships and validate power loss models. The performance of a 7 kW grid-connected ASG was measured and used to validate model predictions. The proposed ASG power loss model improves the prior frictionless power model significantly and was generally capable of predicting the power output of a real-world ASG. (C) 2017 Elsevier Ltd. All rights reserved.