On-Site versus In-Factory Installation of Solar-Plus-Storage in Modular Construction

High initial cost, mainly due to inefficient construction processes, remains the greatest barrier for residential adoption of solar plus storage (SPS) systems. Modular construction, with a factory-controlled environment and control over the home design, is well suited to address these issues (e.g., efficiencies, waste, inventory control, and quality). Furthermore, these areas have great potential in modular construction to address the high initial cost issue. This study focused on the integration of solar-plus-storage installation upstream in modular housing. Although moving the solar-plus-storage installation process into the factory has many barriers (e.g., change of the scope of work at some workstations without affecting the whole production line, change of quality control, warehousing of solar-plus-storage in correct conditions, change in the supply chain, and required certification of workers), the great potential presented by modular construction methods warrants the study. This study analyzed on-site installation cost and in-factory installation cost through factory information modeling, as well as job safety. Results reveal that integrating solar-plus-storage installation into the production line of modular construction achieved a 37% reduction in installation time compared with onsite installation. Overall, a 21% reduction of total cost could be achieved if solar-plus-storage is installed in-factory. Furthermore, with the in-factory approach, 28% of safety hazards related to solar-plus-storage installation activities are removed. Such an approach could increase solar-plus-storage installation productivity, reduce inspection time, reduce costly on-site rework, and address the solar-plus-storage system affordability issue overall.