Solar panels installed on a bus

Keolis Denmark and Lectron test flexible solar panels on buses

Solar panels installed on a bus
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PostedJAN. 21, 2022
Words byKeolis
Recently, Keolis and power supply specialist Lectron tested roof-mounted solar panels on buses in Denmark to measure savings in fuel consumption and reductions in CO2 emissions. The test was the first of its kind in Denmark.

Context: Putting solar panels to the test for green mobility  

Incorporating solar into the energy mix of public transport vehicles and infrastructure has long been an ambition of many operators. Solar radiation is historically a stable source of energy, with solar cell technology being thoroughly tested and widely considered safe. As an investment, solar energy represents an environmentally friendly option to reduce greenhouse gas emissions — an obvious choice as a supplement to the energy consumption of special vehicles in a drive towards green mobility. A bus roof has a large, otherwise unutilized surface that offers great potential for energy supplementation by installing solar panels. The only thing left to do was put it to the test.   

Innovation: A green mobility project requiring external solar panel expertise   

It is a given that installing solar panels on buses will help supplement power with a green source, thereby reducing reliance on fossil fuels. The challenge, and the reason for the test, was to find the perfect system configuration to maximize the use of the energy produced by the solar panels, which required the in-depth knowledge of both the Keolis and Lectron teams. 

Solar panels on a bus

Klaus Hansen, Account Manager, Lectron ApS

Klaus Hansen

Account Manager, Lectron ApS

"Keolis Denmark was able to rely on and leverage Lectron’s specialist knowledge in electrical power supply and related IoT technology."

Value: Fuel savings and carbon footprint reductions achieved  

The result was a minimum fuel economy of 5%, with this figure growing considerably in sunnier countries and with the installation of newer, more efficient solar panel technology down the line. Extrapolated across an entire fleet, the potential for diesel savings is substantial, saving 100 liters of fuel per month per bus. Over the duration of the test, 387 liters of diesel were saved, which represents 1 ton of CO2 discharged. 

 Solar panel technology for bus

Next Steps: Striving for even greener mobility through advances in solar panel tech   

With the first test being a success, future testing will focus on electric buses to increase the autonomy of the batteries and their lifespan, and will use newer solar panels capable of producing 20% more energy. 



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minimum fuel economy thanks to the solar panel technology


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liters of fuel potentially saved per month per bus


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ton of CO2 discharged over the duration of the test

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