This is quite fascinating, if true. Having studied solar photovoltaics fairly extensively in both undergrad and grad school, I'm a bit skeptical that he achieved such efficiency with such a simple design, but it's not completely impossible. It's important to note, though, that most of the cost of present day polysilicon solar cells comes not from the semiconductor device and contacts, but from the module and supporti…
I think the "interesting" part of this is that you could generate useful amounts of electricity with panels that could be made and repaired/maintained/recycled in a very DIY fashion. They would definitely be worse than commercial Si panels in every other way, but when a ~400W panel on my roof breaks, it's probably going to wind up in a landfill rather than me troubleshooting and fixing it. A 5%-efficient panel that was very DIY-friendly would be pretty neat.