Yea he's selling it for more than he's buying it. So this isn't really a sustainable scheme, and won't work on a much larger scale. He's basically being payed for doing something for the environment rather than for the value of the power he's producing.

That 10 year payback period you mentioned before, and which I've heard elsewhere too, is probably for selling power of any sort, which would be safe from changes in public opinion about renewable energy, safe from oversupply of that product, and applicable to other states and countries.