Ya, I thought it was odd to, but it looks like it might actually work. I do have to ask how green (no smart comments) are balloons that will break down over time.
This will probably make a good roof top engine at retail centers.
My money is still on the sterling engine for daytime power generation.
I can see the balloon thingy maybe being a little cheaper than a stamped metal reflector, but only by a few bucks, if that. Everything else is standard issue and standard cost. They still need a tracking device, water and power conduits, etc.