Trucks with photovoltaics on the roof. Is it profitable at all and for whom?

The SolarMoves project commissioned by the European Commission lasted three years. This is the result of cooperation between scientists from the Fraunhofer Institute for Solar Energy Systems (ISE), the Dutch research organization TNO and a supplier of solar systems. They combined measurement data from one million kilometers traveled with satellite data and weather information.

The entire spectrum of vehicles took part in the tests – from light delivery vehicles to long-distance combinations with a tractor unit and a semi-trailer operating in various climatic conditions. They included electric trucks, diesel vehicles, refrigerated trucks, and city vehicles. The final report from December 2025 does not provide a simple and clear answer, but it indicated that the main obstacle to the dissemination of this technology is not the efficiency of the panels themselves, but the regulatory environment.

Large diesel vehicles have benefited. For example, cold rooms

Photovoltaics on the roof or on the side of the truck were not intended to replace the classic drive. The main task of the solar panels was to power auxiliary systems in order to reduce energy consumption from the engine or traction battery.

Light and flexible photovoltaic models were used for testing, which did not significantly affect the mass and aerodynamics of the set. They were mainly installed on the roofs of semi-trailers, refrigerated trucks and tractor cabs. Photovoltaic installations mounted on the sides of trailers were also tested, but mainly to increase the energy generating area, and not as a replacement for roof panels.

Mobile photovoltaics most often powered refrigeration units, parking air conditioning, telematics systems and other auxiliary devices from trucks. It turned out that photovoltaics in road transport makes sense, but not in every case.

The most clear conclusions concern diesel vehicles. Solar panels mounted on long-distance sets can pay for themselves in less than a year. They significantly reduce fuel consumption by relieving the alternator and prevent the batteries from discharging when stationary.

According to the report, under favorable circumstances, long-distance vehicles with panels could generate over 32,000. euro savings over five years. Therefore, the payback period was approximately 0.7 years. Additionally, the reduction in CO2 emissions reached up to 9%.

Electric trucks are not necessarily profitable. The problem is the regulations

The situation for electric trucks was different. It is true that some of them achieved a positive economic result (return on investment after 2.8 years for long-distance sets and 4.6 years for city vehicles), but there were also installations that turned out to be unprofitable in the analyzed period of five years. According to data from the SolarMoves project, installations mounted on the roofs and sides of trailers can generate up to 90 – 110 kWh of energy per day in summer. This translates into approximately 50 km of additional range for the electric long-distance set.

But the problem is the applicable legal regulations and the structure of the transport market. The energy produced by solar panels on trucks is not included in the VECTO system, used to hold truck manufacturers accountable for CO2 emissions. Hence, there is no motivation to factory install PV installations.

Moreover, the costs of such a solution must be borne by the trailer owner, while the savings go to the vehicle operator, which is why the authors of the report recommend including photovoltaics in the VECTO system and recognizing the energy produced by vehicles as renewable under the RED III directive.