Hey there, solar Fools. After a brief earnings season hiatus, we now return to our regularly scheduled solar roundup.

We saw a slew of earnings results this week, from European leading lights Q-Cells and REC Group to wafer whiz LDK Solar (NYSE:LDK) and a freshly cashed up Canadian Solar (NASDAQ:CSIQ). In addition to the dollars and cents, each company had interesting things to say about ongoing technological developments.

REC Group, which handles everything from polysilicon production to module manufacturing, announced that it's working with partner Silicon Genesis to develop an ultra-thin wafer that can "shave years from the industry's goal of reaching grid parity." (Grid parity means having costs per kilowatt-hour on par with electricity derived from fossil fuels.) If REC achieves anything approaching 50-micron thickness in high-volume production, its edge over LDK, Trina Solar (NYSE:TSL), and Yingli Green Energy (NYSE:YGE) would be anything but thin.

Q-Cells, meanwhile, revealed a very strong commitment to upgraded metallurgical grade silicon (UMG). The company expects UMG, a cheaper alternative to virgin polysilicon, to make up about 30% of supply next year, and over half of supply in 2010. That's huge news from one of the top solar cell companies in the world. LDK, meanwhile, is now integrating UMG into a new line of wafers.

The other big news this week was PG&E's (NYSE:PCG) award of two huge solar power plant deals to thin-film start-up OptiSolar and SunPower (NYSE:SPWR). The deals demonstrate that both crystalline and thin-film PV technologies are currently considered economically viable on a large (i.e. several-hundred-megawatt) scale.

Before popping the cork on the champagne, however, I think it's important to consider the caveat that these projects are contingent upon extension of the investment tax credit. This measure continues to meander in Congress, thanks in part to our leading presidential candidates, both of whom failed to vote on the measure before the summer recess. If you're a solar investor or supporter, think about calling your senator and encouraging him/her to get this measure passed.

Fool contributor Toby Shute doesn't have a position in any company mentioned. The Motley Fool has a disclosure policy.