Get Unlimited Range by Adding Solar Panels to an E-Bike

The classic “pair solar panels with an electric vehicle” concept isn’t as foolproof as it seems at first. While an unfathomable amount of energy from the sun reaches the Earth’s surface, solar panels small enough to attach to a vehicle won’t have much area and their output will be low. In almost all cases, their output will only be a small fraction of what the vehicle requires to move and the added weight of the panels will reduce efficiency. But this setup can be useful in niche situations, as shown by Doctorclockwork42’s e-bike equipped with solar panels.

This is practical because e-bikes can operate under assistance from the rider and because people often have time to spare when cycling over long distances.

An electric car always consumes power when it moves, unless it is moving downhill or slowing down. An electric bike, on the other hand, can be ridden like a normal bike. In fact, you may only need to use the bike’s electric motor a small fraction of the time. And if you’re using the bike as transportation (rather than for hobby or exercise cycling), it is probably sitting stationary a great deal of the time. On nice, sunny days, those two factors will come together to make solar panels surprisingly practical for e-bikes.

For this to work as intended, your e-bike must be capable of charging while riding. Many models are not, so be sure to check yours. Assuming it is, Doctorclockwork42 will walk you through mounting solar panels on the bike and directing their output to the bike’s battery pack.

Lithium batteries — especially the large lithium battery packs used on e-bikes — require very controlled charging. That is necessary for safety and to maintain battery performance. Fortunately, many e-bikes (including Doctorclockwork42’s KBO Ranger) have chargers built into their battery packs and just need to be fed an appropriate current. The job of the solar charge controller is to take the raw output from the solar panel (which can vary dramatically) and convert it into a stable voltage. Doctorclockwork42 has his set to 54.6V, but that may be different if you have another e-bike model. In good sunlight, this should provide enough power to charge the battery.

The amount of power provided will depend on the weather and the solar panels. You will, realistically, be limited to a 50W panel. If you use the electric assistance very sparingly and stop for lots of breaks, that should be enough to provide a noticeable benefit. With enough time (a lot of time), it can even give you unlimited range.