Thin-film solar panels that can be printed in high-throughput processes could make solar as cheap as electricity from the grid. Or at least that has long been the promise. But while the panels have shown quite a bit of promise in the lab, they've been very difficult to make reliably at a large scale. Indeed, there have been a series of delays from companies developing printed solar panels.

But now one company, San Jose, CA-based Nanosolar, has started to ship printed solar panels. (See "Large-Scale, Cheap Solar Electricity" for our earlier coverage of the company.) The first cells off the line will be used for a power plant in Germany. The company plans to deliver one megawatt's worth of solar panels for the plant.

It's still too early to tell whether the company can meet its goal of producing cells at $1 a watt, and the company isn't yet disclosing the technical specifications of the panels, except under a nondisclosure agreement. But the fact that the company is shipping a product to a paying customer is certainly a good sign.

The company is marking the occasion by auctioning off the second commercial solar panel to come off its line. You can bid on it here.