Solar Bike Project

THE SOLAR TOURING BIKE

Our project is to design and build a solar-electric recumbent touring bike which will allow two riders to ride in long-distance tours powered only by the sun and our muscles. It’s not intended to be the car of the future, rather an experiment to see how a solar powered touring bike can be made using easy-to-obtain parts. What it’s designed to do is similar to the function of million-dollar solar race cars: go far under only solar power. But it’s made by two guys in a garage, not an army of engineering students spending millions of dollars, which is the case for race cars. We’ve used Bryan’s old 2002 Greenspeed recumbent tandem trike, off-the-shelf solar panels, commercial motors and controllers, store-bought batteries and other components and assembled them over the last year in Bryan’s Sacramento garage. The only large custom component is the solar panel trailer, which we designed and had welded together locally. It’s been a design-and-test, trial-and-error process, a real engineering development exercise—a lot of fun for us techies.

RUSSELL AND BRYAN: SOLAR KIDS

Both of us grew up teething on solar photovoltaics in the 1960s. Both of our fathers were mechanical engineers designing satellites during the California aerospace boom. Both of them brought home cells and panels from work as samples or stress-tested modules. Both of us kids connected these solar modules to toys and radios, learning early the magic of converting light to useful power. Solar powering electric devices is natural to us. But neither of us became solar engineers.

Russ and Bryan first met in the 1970s in student co-op housing at UC Berkeley, and soon infected each other with our bizarre hobbies. Before hot springs were a fad, we sought out long-abandoned holes in the desert to soak in, using topo maps and accounts by 19th century explorers. On one 1985 trip to the Black Rock desert in Nevada, Russell came up with an idea for a solar-powered electric vehicle to roam the flat sun-drenched playas. We would talk about it over the desert campfires but at that time in our lives realization of the idea and 1980s technology made the project impractical.

A dozen years later, in 1997, we decided to begin a series of garage construction projects to see what we might do about our solar bike dream. Together and singly over the next ten years we eventually built four models of solar bikes and tested them on the harsh desert playa. The way we learned about solar and electrical construction between 1997 and 2007 is a wonderful example of homespun engineering which steepened our learning curve and prepared us for what was to come. To learn about those experimental projects, click the “Early Experiments” button.

DESIGNING THE ALL-DAY SOLAR TOURER

The four solar vehicles we built could operate on the desert playa for only one to two hours continuously before they needed to be stopped and recharged. This was ideal for short local transportation, but what we now dreamed about was a bike we could ride all day if we liked, perhaps as much as 200 miles entirely powered by the sun and our muscles. We wondered whether off-the-shelf commercial technology had advanced enough for two guys to build our 200-mile-per-day dream vehicle affordably and without a million dollars or a 50-person university team.

This new design challenge was a lot more ambitious than the intermittent flat-terrain models we’d cut our engineering teeth on. The solar tourer would have to carry two riders and camping gear and tools and spare parts. It would need to be powerful enough to take us perhaps 1,500 miles over a two-week trip. And the trip might include multiple western mountain ranges, maybe even crossing the Continental Divide. We started a massive technical search for what technology was now available.