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THEKPV: A Real Solar-Powered Bike With Regenerative Braking Built by DIYer


THEKPV is more than a solar-powered bicycle. Designed and manufactured by Terry Hope, who has actually wrote to us about his bike, THEKPV (The Hybrid Electric Kinetic Photovoltaic Vehicle) is powered by a 50-watt solar cell array, has a battery and a capacitor for boosting its acceleration capabilities.

It’s an interesting design, as it features regenerative braking, solar cells, and a mains charging outlet. Weighing only 44 pounds (20 kilos), the total power of 424 watts installed on the bike can get recharged some 10,000 times.

The A123 batteries have 396 Wh and the Maxwell capacitor has 28 Wh. The most interesting, though, is the solar panel installation, making this bike a truly green one. And, given the fact that you can recharge it in 15 to 30 minutes, gives you an advantage when you want to go shopping on the thing.

Terry writes about THEKPV on his website, thekpv.com (for technical-minded people):

Harvested kinetic energy is converted to direct current and stored in a bank of ultracapacitors, the electricity can be quickly released via the propulsion booster switch. Motion is captured by an extra sprocket mounted on the opposite side of the rear wheel to the electric motor, using five gears engineered to rotate a set of very small 3-phase alternators designed with multi-pole configuration to reduce cogging torque.

Each of these alternators convert alternating current to direct current with 74% efficiency. The regen device frame structure is hand built out of polycarbonate. Usually electric vehicles or electric bikes or scooters equipped with regenerative capability utilize a type of controller that can switch the motor or hub motor into a generator only during braking events.

THEKPV genset is a variable power source precision tuned during acceleration, coasting, and braking events. A similar technology called KERS (Kinetic Energy Recovery System) was used in 2009 F1 racing season, except that formula 1 utilizes a flywheel design from a collaboration of italian electronics specialist Magneti Marelli, and british flywheel specialists Flybrid Systems.

It would had been even more useful if the inventor integrated some pedals, and the entire contraption on a light normal bike, with bigger wheels. Again, the need for pedals is a must, because otherwise you might get stranded somewhere sunless, and there would be no way out.

Here’s a short video of Terry riding his solar powered THEKPV:

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