French nuclear giant Areva kicked off an eventful week in the sector with an acquisition of U.S. concentrated solar power (CSP) player Ausra. This follows Siemens' (NYSE:SI) investments in Archimede and Solel last year, underscoring the attractiveness of solar thermal, as opposed to solar photovoltaics, for some serious heavy hitters in the power market. Areva says it "intends to become the world leader in the CSP market." Join the club, bub.

Elsewhere on Monday, Suntech Power's (NYSE:STP) chief strategy officer told Reuters that he expects polysilicon prices to fall to a range of $35 to $40 per kilogram, down from around $55 per kg. That's around where manufacturing costs stood for the world's leading poly players last summer! Apparently, a bunch of startups are pumping out some decent poly. That arguably erodes too-big-to-fail LDK Solar's (NYSE:LDK) in-house production advantage, which once appeared so promising.

On Tuesday, talk emerged out of Germany that the powers that be may push back feed-in tariff reductions to June from April, which would give developers some breathing room. Here in the U.S., two solar stocks revealed their rather sorry state of affairs.

On Wednesday, Europe's REC issued another gloomy earnings report. Not only did the company have a bum fourth quarter, but the first quarter looks rough as well, with a 20% sequential decline in wafer prices. Higher-cost solar players are plainly taking it on the chin from Asian rivals.

Speaking of which, both JA Solar (NASDAQ:JASO) and ReneSola (NYSE:SOL) made a splash on Thursday. JA Solar reported a booming fourth quarter, while ReneSola snagged a multiyear, 600-megawatt module supply deal. Looking at these releases in isolation, you'd never know times were so tough elsewhere in the sector.

SunPower (NASDAQ:SPWRA) didn't let these guys entirely steal the spotlight, though. Taking a page from the First Solar (NASDAQ:FSLR) playbook, the stateside solar player picked up SunRay and its 1.2- gigawatt solar development pipeline. The company shelled out $235 million in cash, which is quite a significant chunk relative to the $472 million on hand as of Sept. 27. Is this a proactive move, or one of desperation to secure end-market demand? Sound off in the comments section below.

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Fool contributor Toby Shute doesn't have a position in any company mentioned. Check out his Motley Fool CAPS profile or follow his articles using Twitter or RSS. The Motley Fool has a disclosure policy.