The European Union (EU) is undergoing an energy transition. This transition is characterised by a number of important developments. For instance, the number of electric vehicles is increasing, leading to a rapid rise in demand for charging infrastructure. At the same time, grid congestion means only limited space is available for infrastructure and energy prices are rising. Vehicle Integrated Photovoltaics (VIPV), solar energy generated directly by vehicles themselves, can offer a solution.
This emerges from the SolarMoves project, in which TNO and Germany's Fraunhofer ISE are collaborating with suppliers Lightyear, Sono Motors and IM Efficiency. The project investigates to what extent VIPV can provide a solution to bottlenecks created by the energy transition. For instance, many companies want to switch to electric driving but are unable to do so due to a lack of grid capacity. The project is commissioned by the European Commission's Directorate-General for Mobility and Transport (DG MOVE) and will run until the end of this year.
Driving for weeks without charging
The study shows that VIPV contributes significantly to the energy autonomy of vehicles. In central Europe, passenger cars can generate up to 55% of their energy themselves, while in southern Europe this rises to 80%. The study uses 23 detailed vehicle models, from small city cars to heavy trucks, and combines them with meteorological data from Amsterdam and Madrid. Especially urban users who make short trips and park a lot can drive for weeks in the summer months without recharging.
For drivers, this means fewer charging occasions, which is financially attractive and reduces pressure on the energy grid. In urban environments, where public charging spots are under pressure, this leads to less searching, shorter waiting times and lower costs.
Could significantly reduce total energy demand
The benefits of VIPV go beyond individual vehicles, by the way, the study shows. If every new electric vehicle is fitted with VIPV between 2024 and 2030, total grid demand in Europe could be reduced by 15.6 TWh by 2030. This is equivalent to the output of over 2,200 3-MW wind turbines on land.
VIPV not only reduces overall energy demand, but also dampens the peaks that overload transformers. In Amsterdam, in simulations, this led to an effect equivalent to a 25% increase in transformer capacity. In addition, VIPV contributes to a CO₂ reduction of 1.8 megatons by 2030, because electricity from the grid is not completely CO₂-free.
Financial and operational benefits
VIPV can also bring financial and operational benefits, including for the logistics sector. For instance, with VIPV, trucks, vans and trailers are less dependent on charging speed, grid capacity and diesel. For electric trucks, VIPV increases daily range without charging by up to 15%, leading to fewer charging stops and more predictability.
On trailers, yields can reach 55 kWh per day in summer, and up to 90-110 kWh per day if the sides are also utilised. This is enough to power cooling engines or hydraulic systems completely emission-free. For diesel trucks, VIPV leads to lower fuel costs because air conditioning and heating no longer consume diesel. The investment costs for VIPV are thus recouped within 1-2 years, the parties calculate.
Data from practice
SolarMoves stands out for its use of real-world data. For example, sensors were fitted to cars, vans, trucks, buses and trailers, which recorded data on solar radiation, position, speed and shadow for months. The data collected showed that solar irradiance in practice is lower than assumed in models, mainly due to parking behaviour. Many vehicles are parked in the shade, which can halve solar radiation. The researchers therefore highlight the importance of behavioural modification and cleverly designed parking spaces to increase the impact of VIPV.
To realise the potential of VIPV, the SolarMoves project says follow-up steps are needed, such as a European framework recognising VIPV through the Renewable Energy Directive. In addition, VIPV output should be included in the VECTO trailer calculation model for determining fuel consumption and CO₂ emissions. Enshrining VIPV in the Worldwide Harmonised Light Vehicle Test Procedure (WLTP) or similar regulations, stakeholders call essential to be able to use CO₂ reduction for tax incentives and guidelines for 'solar-ready' parking areas.
