announced that the manufacturing costs for its thin-film photovoltaic panels had dipped below $1 per watt for the first time. With comparable costs for standard silicon panels still hovering in the $3 range, it's tempting to conclude that First Solar's cadmium telluride (CdTe) technology has won the race. But if we're concerned about the big picture (scaling up solar until it's a cheap and ubiquitous antidote to global warming and foreign oil) a forthcoming study from the University of California-Berkeley and Lawrence Berkeley National Laboratory suggests that neither material has what it takes compared to lesser-known alternatives such as—we're not kidding—fool's gold.