The manufacturing costs of solar power — or at least for thin-film photovoltaic panels — have broken below a golden benchmark, as reported by Popular Mechanics: $1 per watt.

First Solar, based in Tempe, Ariz., has brought the costs down to $0.98 per watt. The company says that further cost reductions will be achieved as technological and manufacturing process potentials are reached.

But things are not all rosy since reaching this milestone of sorts. Popular Mechanics reported:

Despite the buck-per-watt announcement, First Solar’s share price plummeted more than 20 percent on Wednesday, thanks to warnings from CEO Mike Ahearn about the effect of the credit crisis on potential solar customers—as much as 10 to 15 percent of current orders might default. He recently told analysts in a conference call that “as good as things look for the mid-term and beyond, the short-term outlook for the solar industry in our view has never looked more difficult.”