One of the main goals of the solar energy industry is making solar technologies cost-competitive with other forms of energy. In particular, balance-ofsystem (BoS) costs associated with the installation of photovoltaic (PV) systems require significant cost savings to stay competitive with conventional energy sources. Significant potential for cost savings exists through increasing the productivity of the labor force installing the system. A gap in knowledge exists regarding approaches to measuring and improving solar installation labor productivity. The objectives of this research are to design a proper method for conducting time and motion studies for solar contractors, collect and aggregate data related to installation practices, and examine factors that affect solar installation labor productivity. In order to achieve these objectives, the Georgia Technology Research Institute (GTRI) laboratory, in partnership with the Rocky Mountain Institute (RMI), conducted time and motion studies on residential and commercial projects sites to collect and document data on the steps in the installation process of PV systems. An aggregation and analysis of data recorded for each step in these studies was performed to estimate the time to accomplish each task and identify the patterns that affect labor productivity. For this research, the proposed time and motion study approach was examined on two residential and commercial solar installation projects. The findings of the research show that conducting proper time and motion studies can determine the time spent on solar PV installations activities, in order to better understand which activities consume the most labor time and what types of contextual variables have greater impacts on installation labor productivity.