Any discussion about the week in solar has to start with what's going on at First Solar (Nasdaq: FSLR). The company lowered guidance this week, and the market has punished the stock to new depths. I do find it somewhat ironic that the market has punished the one profitable solar company more than others, but when you are king of the mountain, it's a long fall from the top.

Despite the disappointment around First Solar grabbing most of the headlines, there were other notable events happening in solar this week.

Another big name in solar
Canadian Solar (Nasdaq: CSIQ) announced it was supplying 2.5 MW of solar modules to a rooftop and carport solar system being built by Siemens. The size of the project itself isn't notable, but the partner is.

Siemens joins a growing list of large, multinational companies that are investing in solar, in one way or another. Berkshire Hathaway (NYSE: BRK-B), Total, and General Electric (NYSE: GE) are just a few notable names recognizing the power of the sun.

The shakeout continues
The solar world lost another company this week and may be close to losing another. Solon, a German module manufacturer and power plant developer, filed for insolvency this week after being crushed by $500 million in debt.

Energy Conversion Devices looks to be following the same path and is currently in discussions with note holders about modifying the company's capital structure. ECD also deferred an interest payment that was due yesterday, which it has the ability to do with a 30-day grace period.

Talking with debt holders about modifying terms and missing interest payments aren't exactly signs that your business is strong, and before long ECD will likely be headed to the trash heap.

Foolish bottom line
Solar stocks have had a lousy 2011 by any account. But it's also important to keep an eye on industry trends and partnerships to see how the industry as a whole is doing. Earlier this week I highlighted a few of the positive trends here in the U.S., where industry leaders see a bright future. And as I've highlighted above, big companies are beginning to put big money into solar.

The shakeout will continue with lower tier companies like LDK Solar (NYSE: LDK), JA Solar (Nasdaq: JASO), and ReneSola (NYSE: SOL) coming under increased pressure, but a few failures don't spell doom for the industry.

Interested in reading more about solar? Add your favorite stock to My Watchlist, which will find all of our Foolish analysis on this stock.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.