At 55 mph, a conventional bike like the Enertia will use roughly 6kw. Conventional solar panels (100w/m^2) mounted on all available horizontal surfaces (typ $200/m^2, likely $1k+ to shape panels to fairing) would produce around 100w, giving approximately 1 minute of riding per hour of charge.
Riding at reduced speeds - say 30 mph - might cut the ride power in half, giving you a minute of riding per 30 minutes of charge. If you push the bike at 1 mph, you're going to be traveling farther under your own power than you will be under solar. And of course solar will not help you at all should you be stranded at dusk/dawn/evening.
Another way of looking at it - in a commuter application where the bike is parked in the sun all day, fixed solar panels could add another 300-600wh of charge back to the battery on a good day with no cloud cover.
Stirling engines are indeed cool. A wood burning bike is a neat idea, and
feasible.
