The kit from the link looks like a 12V solar panel with a 12V battery and a standard 12V DC to 120V AC power inverter. You wouldn't want to plug the SB power supply into the inverter, but instead convert the 12VDC directly to 5VDC using a high quality voltage regulator.
Or, to take it a step further, go for the all-battery conversion from Red Wine Audio (
link) or do something similar on your own, and use the solar kit's battery instead of Red Wine battery supply.
Either way, you're just running the SB off battery power and recharging the battery with a solar panel or regular household AC. It might be interesting to power the SB directly from the solar panel. While the output voltage of the solar panel might fluctuate depending on the amount of sunlight, the voltage would probably stay >5VDC until the sun sets, so the voltage regulator would be able to supply a constant 5VDC all day. Of course that wouldn't work with the Red Wine mod since it takes both 12V and 5V feeds.
-Rob
