Just for history's sake, the passive component requirement is not impossible, its just impractical with all the modern components that we have today.
Back in the early days of automobile radio, the only active devices were vacuum tubes. These tubes require a large plate voltage. The problem because how to generate this voltage. The solution was a relay and a transformer. The relay contacts connected the transformer's primary to the battery. The relay's coil was attached to the battery with a set of normally closed contacts. Every time the relay pulled in, it broke its own relay current and the relay would drop back out before energizing let again. The allowed the relay to produce pulsed DC to the transformer which stepped up the voltage and fed the plates of the vacuum tubes.
As far a power generation from solar cells, so some searching of the Texas Instruments web site. They release a new IC a couple of weeks ago that is designed to take the varying low voltage output from a solar cell and step it up to levels that can be useful to microcontrollers etc.