Julian OH8STN is featured on my blog roll, to the right. Just a few days ago, he made a video about operating a field station totally from solar power, off the grid. The South Plainfield Amateur Radio Club does this every Field Day, by using solar power to charge up our batteries. Our radios run from this power source for the entire 24 hours.
Last year, I purchased a portable, brief case type of solar panel, along with a charge controller in order to accomplish the same goal. I haven't taken it out to the field yet, but I have used it from the back yard; and I know it will work if needed in an emergency situation.
72 de Larry W2LJ
QRP - When you care to send the very least!