Retrofitting Solar Panels on Trucks: Lessons Learned from the Monitoring Project on PV-Equipped 200 Trucks in Japan

The decarbonization of the transportation sector necessitates the adoption of practical measures that can be implemented within existing fleets. One such measure is the installation of solar panels on trucks, which has shown potential to reduce fuel consumption in heavy-duty vehicles (HDVs). This study presents lessons learned from a monitoring project involving 200 commercial trucks retrofitted with 300–500 W solar panels, aimed at supplementing battery charging and minimizing alternator operation. The system incorporated commercially available flexible photovoltaic (PV) modules, adhesive mounting techniques, a charge controller, and a data logger housed within a control box. Documentation covered installation procedures, wiring practices, and safety considerations across various truck models, with additional insights from electrical contractors regarding labor time and costs. Results indicate that adhesive-based mounting can be carried out safely and reliably without structural modifications, although wiring and control box placement constitute the most significant portions of the installation process. The project further identified variability in installation duration and economic viability, depending on vehicle configuration and technician expertise. Overall, the findings affirm that vehicle-integrated photovoltaic (VIPV) retrofits are both technically feasible and operationally robust. They also underscore the practical requirements, constraints, and workforce considerations essential for scaling deployment within commercial fleets.