Abstract
Smart Grid software applications are a kind of ultra-large-scale system (ULSS) where complexity has a profound impact on their quality and defect profiles. Their complexity also adds challenges to the process of designing studies to investigate their complicated software development. In this paper we propose an empirical research agenda to study the relationship between the characteristics of Smart Grid software applications as a ULSS and their software defect profile. We base our discussion on a structured literature review and on an ongoing case study in a software company. Future studies are needed on certain characteristics of Smart Grid software applications that affect their defect profile. For this purpose, not only the software development companies but also the grid utilities should be studied.