That may be about to change.
Scientists at Lawrence Berkley National Laboratory have announced a breakthrough with a high efficiency solar cell that can work... in the dark! The new full spectrum solar cell can capture lower bandwidth light like the moon, stars and other energetic sources. Scientists at Ohio State have a second generation panel in the works that improves performance loss due to heat.
In the meantime you can just grab a few cans of photovoltaic spray paint. That's right, turn the barn into a battery!