When German automotive startup Sono Motors introduced a pre-production prototype of its Sion solar-electric family car as part of the online-only CES 2021, the company also showed a huge solar trailer built with Finland's Valoe. Now that idea is taking to the streets, but in the shape of a specially developed passenger-carrying trailer bus.
Sono reckons that the photovoltaic cells on the hood, roof, sides and back of its upcoming Sion solar-EV could add as much as 245 km (152 miles) of range to its batteries per week in ideal conditions. But how much energy could be harvested if solar panels were installed atop a passenger bus? Sono has partnered with Munich's MVG to find out.
Some 20 semi-flexible photovoltaic modules have been installed on the roof of a bus trailer that will travel the roads in the Munich metropolitan area behind a passenger bus operated by local transport company Münchner Verkehrsgesellschaft (MVG), to test real-world energy yields and gauge the technology's potential in daily use.
"The partnership with MVG illustrates the enormous potential of our unique solar technology, which is now being used for the first time in the company's history on public transport," said Sono's co-founder and CEO, Laurin Hahn. "This is a milestone in Sono Motors’ mission to make every vehicle solar. Especially in times of rising energy prices and increasing urban area emission regulations, our solar technology offers great added value for public transport operators. City buses and coaches, whether electric or diesel-powered, offer a lot of space and are out on the road every day. The first solar bus trailer for MVG will hit the streets of Munich in the future and allow MVG passengers to experience solar mobility in daily use."
This iteration of Sono's proprietary PV tech was developed specifically for implementation on buses, and features the company's MPPT central unit as well as a charge controller featuring an algorithm to optimize energy yields. The solar bus trailer that will serve as its rolling testbed was created in collaboration with MVG, and features some 12 sq m (129 sq ft) of PV modules rated at over 2,000 watts. It's expected that the energy harvested by this setup will be enough to meet the needs of the HVAC system and the trailer's steering system.
"The photovoltaic system on our bus trailer now allows us to test under real conditions how well the power generation works and whether there are perhaps routes in our network that are better suited than others for this type of power generation," said MVG's Veit Bodenschatz. "The question of what energy savings can be achieved by using solar energy are, of course, particularly exciting against the background of current fuel and energy prices."
On that, Sono estimates that such technology has the potential to save 2,500 liters (550 gal) of diesel and 6.5 tonnes of CO2 per bus per year, meaning that operators running a modest fleet of 300 buses could be looking at annual savings of up to 2,000 metric tonnes of CO2.
The solar tech does come with its own environmental footprint of course, with calculations showing some 1.5 metric tonnes of CO2 being produced per bus or bus trailer during the production of the system. But Sono reckons that this one-off figure could be successfully offset in less than a year of operation.
"We need a change of course in the transport sector," said Munich's vice mayor, Katrin Habenschaden, at today's launch. "Transport still misses the climate protection targets by a very wide margin, and this also has a direct impact on air quality in Munich. The solar buses can be a cornerstone in this urgently needed change towards climate-friendly mobility. I am convinced by the idea, as a lot of fuel can be saved here, and CO2 emissions can be significantly reduced.
"We are already working with MVG to completely convert our bus fleet to electric drives. Harnessing the power of the sun is of course even more sustainable and I hope that this pilot project will show that we can also extend the range of the e-buses using solar energy. I am particularly pleased about this cooperation with our MVG that such an innovative idea comes from a Munich-based company."
Following technical approval by local authorities, the trailer bus will head for the streets of Munich to determine if those estimates add up to meaningful real-world savings.
Other recent collaborations have seen Sono's PV tech installed in a driverless shuttle and an electric panel van, and the company has signed eight more letters of intent so we could be seeing more examples of solar integration in transport solutions in the near future.
Source: Sono Motors
