Gantner Instruments (Juergen Sutterlueti, http://www.gantner-webportal.com) and Steve Ransome (www.steveransome.com), using outdoor IV measurements on a wide variety of module technologies have developed a PV module performance model based on defining loss factors that affect the shape of the IV curve. Details of this model can be found on publications listed on Ransome’s website. We will include a summary of the model in the near future.