Well, starting about 3 1/2 years ago...
It seems, BTW, that the second attempt at the pilot installation in Sand Point actually went considerably worse than the first. The first was delivered with ALL panels broken (none produced any electricity, and about 2/3 of them did nothing at all, and the LEDs on the remaining panels gradually failed). This may have had something to do with the panels having been hastily made over the course of a couple of weeks with untried methods and/or equipment when they suddenly realized they were supposed to install it in the near future, and there being no real attempt to keep water out of the installation, and it being installed into pooled water. However, the second try went rather worse. While all panels lit up this time, about a third of them gradually failed, then the installation CAUGHT FIRE. This may have to do with it again not being weather-tight, but also they apparently used ordinary consumer-grade extension cords internally, despite this thing producing much higher currents at much smaller voltages than these are rated for.
Apparently, the THIRD try actually works. And produces 55% of the output per unit area of a sanely designed and properly installed ROOFTOP installation, just like the similar prototype installation in the Netherlands does. And the only firm cost estimate is for the French system, which is 6 times the cost of rooftop solar. So, six times the cost, half the output, IF IT WORKS. (Result: It cannot pay the extra cost over using proper pavement.) That's not dealing with the problems of paving a road with GLASS TILES glued down to extremely brittle silicon wafers.
This foolishness has been kicking around since at least 2009 when it was in Wired, and all the way back then they were talking about needing to spend $50 million to determine if there was a material that would make this physically possible. This rather important phase of the research has not been done. In fact, one of the characteristics of this outfit is a general lack of numbers, and using numbers deceptively when they do have them.