The initial simulations indicate that 5-10% of fuel savings in a plug-in hybrid truck is possible in Sweden, which is not a particularly photovoltaic-friendly country. In Spain, the result might be two times higher (80% more hours of sunlight).
The idea is to use an 18-meter long solar cell clad trailer with a total area along the sides and roof of 140 square meters. It's estimated that it should provide 14,000 kWh (14 MWh) annually in Sweden.
The electricity from the solar panels would be used directly by the PHEV vehicle (to drive or charge the battery).
A separate idea is to evaluate whether during the weekends (when not in use), the trailer could be used to send electricity to the grid (kind of like a V2G application).
"The truck will be operated in daily transport assignments by the Swedish haulier Ernst Express, which also collaborated with Scania in trials of the world’s first electric road with overhead catenary lines."
"The research project will also examine whether the trailer can feed electricity into the grid when the batteries are fully charged and the truck is parked, for example, over weekends."
We are cautious about the economic viability of the solar trailers in Sweden, especially since the company noted that the sun is weak except during summer, but in many markets, it might be an interesting solution.
We already saw multiple bus manufacturers that offer solar roof option, although only a small one for an auxiliary system, never to drive the vehicle.