No, he just compared it to an inefficient distribution (a roof with panels on the south and the north side).

As was pointed out in other comments there are 20 cells on the tree and, most probably, 10 cells on each side of the roof. Had he really compared to 20 cells in a flat panel array, he would have found that the tree distribution is less efficient than the flat panel.

By the way, there is an optimum inclination (vertical angle) of a photovoltaic module, which in Europe is between 30 and 50 (depending on the latitude and the height), see this map (pdf, 11 Mb).

I nevertheless admire the idea and the work of the young boy. As an adult I'm sure he would have spotted the error in the result, unlike the jury and the submitter of the story.

Visible light would not be safer here, since the pulse is just 100 ns long and thus much faster than any reflex of the eye.

If I read the original Science paper correctly this is nothing more than an etalon in front of an absorbing material (i.e. a plate of silicon, as they used in their experiment, in front of a black sheet of paper). Of couse it works as a selective absorber or "anti-laser", this is well known.

I wonder if they wrote the Science paper just to show what you can publish using a lot of buzzwords...

The original image can be resized without showing the watermark, see their demo page (and press Ctrl +/- if you browse with Firefox). But so can the re-encoded picture, it shows the watermark only at the zoom level of 100%.

From this I suppose that there is also one zoom level at which the original picture shows the VOID watermark (you better choose it to be an odd value)!

The linked article at Connectify says they measured a resistance of 2 Ohm, but on the picture I read 2 MOhm!

Check yourself with the large version of the picture.

I'd say it's nearly a Gi$ = 1,073,741,824 $.

No, it's not legal to copy the articles to Wikipedia, since they grant no other right than free view. See their copyright: basically the author retains the copyright, and grants Stanford the right to publish the article electronically.