This circuit generates an usable power 5V good for charging portables. Even lighting a White LED Array.
A Supercap Flywheel may be good addition to this, these kind of chips can also add supercap power management, as it will take a lot of current to charge up. This will keep power flowing when the sun goes behind the clouds.
"Obtaining all the available energy from a solar panel requires a switch-mode step-up or -down converter and battery charger, in addition to the battery. The converter must ensure that every bit of energy taken from the solar panel is efficiently stored in the battery for future use."
The MAX856-MAX859 are high-efficiency, CMOS, step-up, DC-DC switching regulators for small, low input voltage or battery-powered systems.