Trucks are arguably not the most aerodynamically-efficient vehicles around. The boxy shape cannot be avoided, though, as it is the most effective way of maximizing load space — the whole point of big rigs, basically. Therefore, truck manufacturers have to be a little bit creative in solving the fuel-economy problem for their vehicles.

One solution that Swedish truckmaker Scania is eyeing at is to cover the trailer with lots of solar panels. Pulled by a tractor head with a plug-in hybrid electric powertrain, the idea is for the photovoltaic cells to provide some of the electricity needed to charge the truck’s batteries. As a result, some of the charging load is taken off the tractor head’s engine, which lessens fuel consumption.

The sides and roof of the 18-meter trailer will be clad in solar panels. Ernst Express, a local hauling company, will do the road trials through actual delivery runs within the country. Another thing that is being looked at is the possibility for a fully charged trailer to supply power to the grid while parked.

It is estimated that the solar trailer will improve fuel economy by up to 10% in Sweden where the sun is weak almost all year round. Conversely, the amount of sunlight that Spain experiences annually should bring in even more fuel savings – as much as twice that in Sweden.