I am part of a project that electrifies refrigeration units that operate on trucks (mainly last mile distribution of temperature-sensitive goods). We've installed solar panels on top of the trucks before and the results were very poor. Apart from the various problems we ran into (required thin and flexible panels compatible with automatic car wash brushes, building shades covered the panels in a large portion of the day, etc.) the amount of energy recovered was still very small. Even though the actual results seem great, it's still hard to say something about its performance in real-world usage.