You're exactly right in your assumption Acreo, the bottles function like a prism and refract natural light in every direction.

Also, for anyone who was wondering why you would add bleach to the water before sealing the bottles: bacteria. If the bottle has been exposed to open air for any period of time, or if you're using tap water, or any of a number of other circumstances, the water will have bacteria in it, which will grow and bloom in the sunlight. The 2 capfuls of bleach kills all that so that the bottles would never have to be emptied and cleaned (so long as the plastic holds up).

I also did a bit of digging at work on the university internet and found something very interesting in relation: internal solar power. Apparently someone in boulder who saw this had an idea: convert his garage into a solar farm. So what he did was put approximately 200 of these bottle-lights in his garage roof and lined the rest of the roof with solar panels. He then lined the interior of his garage with solar panels, effectively quadrupling the amount of solar energy he can harness with just the panels on the roof.

From what he was saying in the article, the only tradeoff he has is that he has to park his car in the driveway, but at the same time, he hasnt had an electric bill over 10 dollars since he started it (and the 10 dollars was just his service fee and taxes). He also actually sells electricity back to the local electric company, Xcel, and makes more than the 10 bucks. So effectively, the electric company is PAYING him every month instead of vice-versa.

The only real caveat that I can see is that you would want to make sure to do this in a detached structure from your house, because I know from firsthand experience that solar panels generate a LOT of heat and would probably cause your air conditioning to be in overdrive most of the time if you did it with an attached garage or room. Although, and I can think of several engineering possibilities for doing so, this would also provide you with cheap heat for your home in the winter on days that its sunny and cold. Could actually be done with underground insulated ducting, an air flow control flap and a fan with an on/off switch inside the main house.