i think as a source of light, LEDs are the best, they are the lowest consumption to light output that you are going to get.
you could then have a few solar pannels on the roof, and then a deep cycle camping battery in the garage to run the LEDs,
the battery charges during the day, and runs the LEDs at night. with enough solar panels in parallel you should be able to charge the batteries before the next night.
thats what i would do anyway,
