Applying Lean Process Principles to Improve Labor Efficiency of Solar Photovoltaic Installations

Abstract

Balance of systems (BoS) includes all costs related with solar beyond the photovoltaic modules and inverter system. BoS constitutes 78% of the cost of rooftop residential PV systems and 73% of the cost of commercial rooftop PV systems. An essential step in reducing the overall cost of PV systems is a systematic approach to labor costs reduction, supported by an understanding and quantification of the activities that make up the installation process. Historically, time and motion studies have occurred on standardized factory floors, but have been extended to the construction industry. Now this method is extended to solar PV systems, addressing barriers such as non standardized hardware, ad-hoc nomenclature, ad-hoc processes, and varying contextual parameters. The proposed methodology takes a three pronged approach to addressing these barriers, including initiation of a formalized domain specific language (DSL), utilization of a flexible site log, and creation of a robust data repository. The preliminary data from multiple residential sloped roof and commercial flat-roof sites provide comprehensive testing and validation of the proposed methodology. The data collected is used to identify the theoretical minimum installation and suggest the application of lean construction practices to further reduce installation labor and overall BoS costs by >50%.