The nice thing about e-mobility: Those who want it can drive with clean solar power and thus protect the environment. There are now many approaches to harmonize the climate-friendly energy source with the mobility structure.
If the burgeoning e-mobility is to make a substantial contribution to climate protection, as much power as possible must come from renewable sources. Among other things, the booming photovoltaics could provide this clean energy to the currently rapidly increasing number of e-cars and e-scooters. In the meantime, there are increasing approaches to merge photovoltaics with cars and the traffic structure. There are some promising levers that could make our mobility of tomorrow more climate-friendly.
Not strong enough for the crowd
The most obvious and also well-proven option is the integration of solar cells into the outer shell of electric vehicles. Since the 80s, the Solar World Challenge, which now takes place every two years, has used experimental, lightweight electric vehicles in which large-scale solar panels are used as the exclusive energy source for the drive. In the case of passenger cars for the mass market, on the other hand, comparable applications are still the exception and, in relative terms, are not very efficient. A currently available series solution is available for the Toyota Prius, which can optionally be ordered with PV technology in the roof. The solar module can generate electricity for up to 5 kilometers per day and up to 1.000 kilometers per year. However, the option costs exactly 3.000 euros extra. With energy costs of around 6 euros per 100 kilometers, the investment would yield a profit after 50 years at the earliest.
The electric van Sion from Sono Motors, which was initially announced in 2019 and now for 2022, promises significantly more benefits in relation to the costs, and with a comparatively large solar cell cover, it is supposed to generate traction current for up to 34 kilometers per day. The model, priced at 25.500 euros, could even be used independently of the charging infrastructure with low mileage. The E-sedan Lightyear One from Holland, which has already been announced for this year, should even be able to generate traction current for the equivalent of 20.000 kilometers throughout the year. However, the One costs around 177.000 euros including VAT. A significantly cheaper alternative to solar cars could be a loading area cover from the Canadian company Worksport. The “charging station to go”, specially developed for electric pick-ups that will soon be available in large numbers, is supposed to produce 30 percent of the energy required by a commuter for the daily commute with its solar cells. Worksport has not yet announced prices or a specific date of availability.
Bad to implement
Another interesting solution: Instead of clad cars with PV technology, the streets they use could serve as the basis for horizontally installed solar cells. Integrating these directly into the road surface does not seem to work quite as easily and efficiently as the theory suggests. In France, the Wattway project, in which a road in Normandy was paved with solar cells in a pilot test, is considered to have failed. Even with the solar cycle path built by the Berlin start-up Solmove in Erftstadt in 2019, a lot of problems have been reported so far, but not yet a resounding success. An alternative solution could be solar roofing over the roadway. In a research project, Fraunhofer ISE is planning to set up a test facility on the A81 motorway together with its Austrian partners Forster FF and the Austrian Institute of Technology. At the Hegau-Ost service area, a PV system is to be built over the road surface at the end of 2021, under which the cars will drive. It remains to be seen whether such a solution really makes economic sense.
Alternatively, users of e-cars can simply set up a solar infrastructure themselves and then use it specifically for their own vehicle. PV systems on the house or carport roof are suitable for this. If this technology is combined with an intelligent wallbox, the self-produced green electricity can land directly in the lithium tank of the eco-vehicle. Since solar power is now a financially affordable alternative to grid power, such an installation can save money in the medium term. The in-house production of solar power can bring even more advantages in terms of costs, provided the e-car has bidirectional charging technology. Then the vehicle could also supply the house electricity network at night with the solar power stored during the day.
Just as a support
The self-sufficiency principle is already being used for public charging stations. For example, a flagship charging park on the A2020 motorway that was put into operation by energy company EnBW at the end of 8 has its own solar roof, which serves as weather and sun protection and also generates around 38 kW of green electricity at its peak, which is then also used in the tanks Cars lands. However, the roof is only a kind of supplement, because the electricity that is fueled by e-cars on the system will continue to come from the grid. Another self-sufficient solar solution could become interesting for hydrogen filling stations in the somewhat more distant future. The electricity from the photovoltaics could also be used for the production of hydrogen directly on site, which is then fueled by electrically powered fuel cell cars. A study presented in 2018 by the Swiss EMPA (Eidgenössische Materialprüfungs- und Forschungsanstalt) showed how this could work. The concept envisages that filling stations will in future use excess energy to independently produce various types of fuel such as hydrogen themselves. But according to the study, this will probably not be the case until 2035.
Hydrogen produced by electrolysis would ultimately only be a storage medium that makes solar power available when the sun is not shining. Storage parks that use old traction batteries from e-cars are also pursuing a similar goal. In the future, discarded batteries should be given a second life here. Instead of disposing of them or recycling them, they are recycled after the car's life. At the end of 2020, the electric car pioneer Renault put such a battery storage system into operation in Elverlingsen in North Rhine-Westphalia. The system, which was installed in a former coal-fired power station with partners “The Mobility House” and “Fenecon”, bundles 72 traction batteries from the Renault Zoe electric car into an XXL battery with 3 megawatt hours of storage capacity. A similar system already exists in Douai in France. More are to follow. The stationary storage systems take on several tasks on the way to the energy transition. They allow energy from renewable sources to be temporarily stored in order to close the gap between electricity consumption and electricity generation. In addition to e-cars, the giant stationary batteries could also supply households with climate-friendly solar power at night.