Absolutely! If you have a solar system on your house, it generates electricity that is fed back into the grid. This electricity can then power anything, including your computer.
You can also buy a small solar panel to take with you when you are traveling which charges a battery that is charged through the current that is generated by the solar panel. I recently saw one of these systems at Costco. It had a small device that also was an inverter, that could even run a small Alternating Current (AC) light. It was pretty neat. You could plug your USB cable from it into your computer.