Improvements have been made to the fuel cell power module (FCPM) within the SOFC cogeneration simulation code developed under the umbrella of the International Energy Agencies Annex 42 project. The main objective of the improved model developed here is to increase generality and applicability, and to decrease reliance on empirical data. A semi-mechanistic model has been developed to represent a nominal 5 kW tubular SOFC stack power module. This model has been implemented into the building simulation software ESP-r. Results illustrating the FCPM system performance as it relates to the output power required by the building as well as results from a number of different operating scenarios are presented in this study. Actual tests performed on a 5 kW SOFC unit were used to validate the model. The simulation results are found to correlate well with experimental observations. The improved model also allows for manipulation of operational parameters such as fuel utilization, excess air ratio and temperature as well as physical parameters such as cell dimensions and materials. Results from sensitivity and parametric simulations are also presented to demonstrate the enhanced capabilities of the model.