You're right! I can't wait for 14 June 1933!

OK, there's a crap-ton of people making this same observation, so I'll reply to the first: Current solar cells absorb light in the visible spectrum. Commercially available solar cells range from 5%-19% efficiency. The best research cells are running at about 40% efficiency, again with only visible light. This kid's solar cell adds UV light to the mix. The UV spectrum is much broader and more energetic than the visible spectrum, so a 500x gain over current commercially available PV cells (note, they don't claim 500x better than the *best* commercially available PV cells) is plausible. I think the kid is more likely to have attended the Tesla School than Hogwarts.