Last week, I spotted two reasons for solar investors to sweat, pointing to a pair of tech titans making the lateral move from similar industries. Monday saw the entrance of yet another heavyweight.

AU Optronics (NYSE:AUO), Taiwan's biggest LCD panel manufacturer, announced that it plans to take a stake in M.Setek, a veteran supplier of solar raw materials as well as solar cell equipment. AUO's energy ambitions stretch beyond the upstream solar segment, to solar and other renewable energy systems integration, and the firm has established an energy subsidiary with a dedicated R&D team to pursue these goals.

Get used to it, Fools -- these barbarians will keep storming the solar gate. They're well capitalized and hungry for growth, especially in light of the global recession's impact on their traditional lines of business.

Speaking of capitalization, some solar firms have recently sought to bolster theirs by various means. ReneSola (NYSE:SOL) registered to sell $100 million worth of new stock this week, while Trina Solar (NYSE:TSL) landed some new credit facilities. Nothing new there. The solar pure plays by and large remain dependent on the capital markets (and Chinese banks), rather than internal operations, to finance growth.

Analysts lost some enthusiasm for two solar-related outfits this week. JPMorgan Chase chopped its price target on MEMC Electronic Materials (NYSE:WFR) to $12, citing polysilicon oversupply stretching into 2010. Canaccord Adams, meanwhile, dialed back its bullishness on First Solar (NASDAQ:FSLR) following the company's daylong analyst/investor meeting, which I plan to give an in-depth look early next week.

Finally, on the utility front, PG&E (NYSE:PCG) announced that it's bringing on an additional 92 megawatts of solar thermal power, courtesy of partners NRG Energy (NYSE:NRG) and eSolar. You can read more about that pair's ambitious energy plans here.

Fool contributor Toby Shute doesn't have a position in any company mentioned. Check out his CAPS profile or follow his articles using Twitter or RSS. First Solar is a Motley Fool Rule Breakers recommendation. Try any of our Foolish newsletters today, free for 30 days. The Motley Fool has a disclosure policy.