Analyst upgrades:

• Thomas Weisel upgraded PerkinElmer (NYSE: PKI) to Overweight from Market Weight on valuation as it sees limited downside to consensus estimates. The firm raised its target on shares to $20 from $18.
• Jefferies upgraded WuXi PharmaTech (NYSE: WX) to Hold from Underperform following the Q2 results as it believes the company's cross-selling strategy is paying off. The firm raised its target on shares to $12 from $5.
• FBR Capital upgraded J. Crew (NYSE: JCG) to Outperform from Market Perform to reflect the company's trend-right product, inventory control, unit growth, and strong management. The firm raised its target on shares to $36 from $25.
• Popular (NASDAQ: BPOP) was upgraded to Buy from Neutral at B. Riley.
• Pan American Silver (NASDAQ: PAAS) was upgraded to Buy from Neutral at UBS.
• HearUSA (AMEX: EAR) was upgraded to Buy from Hold at Roth Capital.

Here are some highlights from this past week's earnings coverage from BloggingStocks:

• American International Group Inc. (NYS: AIG) posted a record loss even as it asks for more taxpayer funds.
• AnnTaylor Stores Corp. (NYSE: ANN) shares sank after it missed Q4 expectations by a wide margin.
• AutoZone Inc. (NYSE: AZO) reported strong Q2 results, sending shares upward toward its 52-week high.
• Big Lots Inc. (NYSE: BIG) shares soared after it reported better-than-expected numbers for Q4.
• Chico's FAS Inc. (NYSE: CHS) Q4 loss widened on impairment charges and severance costs.

Chinese solar concern ReneSola Ltd. (NYSE: SOL) is trading sharply higher today after the company reported that fourth-quarter revenue will exceed analysts' expectations. SOL expects to rake in revenue of $157 million to $159 million, compared to the Street's consensus estimate of $154 million.

However, the rest of ReneSola's forecast wasn't quite as sunny. The alternative energy firm warned that it will swing to a fourth-quarter net loss of $125 million to $130 million, prompted by "significant downward pressure" on average selling prices and margins. ReneSola predicted quarterly writedowns of $130 million to $140 million, due to the rapid deterioration in the price and value of materials.

Analyst upgrades:

• JP Morgan upgraded Astoria Financial (NYSE: AF) to Neutral from Underweight on valuation as it finds the stock fairly valued at current levels.
• Seagate Technology (NASDAQ: STX) was upgraded to Neutral from Sell at American Technology.

Analyst downgrades:

• Soleil downgraded Sunoco (NYSE: SUN) to Hold from Buy on valuation following the recent rally and is concerned about rising distillate inventories on the East Coast.
• Deutsche Bank downgraded MedCath (NASDAQ: MDTH) to Hold from Buy and lowered its target to $12.50 from $14 as it believes FY09 consensus estimates remain too high.
• Piper Jaffray downgraded ReneSola (NYSE: SOL) to Neutral from Buy and Canadian Solar (NASDAQ: CSIQ) to Sell from Neutral.
• LHC Group (NASDAQ: LHCG) was cut to Hold from Buy at Deutsche Bank.

Last week, JA Solar Holdings Co. Ltd. (NASDAQ: JASO) posted a quarterly loss and lowered its guidance. But as interest in alternative energy continues to grow, analysts polled by Thomson Financial are still looking for good things from solar energy concerns scheduled to report earnings this week.

Strong growth at Trina Solar Ltd. (NYSE: TSL) in the third quarter prompted it to lift its guidance back in October. Analysts expect the Chinese company to post profits that are 76.3% higher than a year ago, or $1.18 per share on revenues of $268.4 million (+225.0%). Though Trina Solar missed estimates in the second quarter, analysts on average recommend buying TSL. Shares are down 81.4% from a year ago and trading near an all-time low.

Earnings of rival LDK Solar Co. Ltd. (NYSE: LDK) are expect to have risen 47.9% to $0.71 per share on revenues of $486.7 million (+206.6%). Also based in China, LDK has not missed estimates in recent quarters; in fact, it blew past expectations in the second quarter. Yet the consensus recommendation is to hold LDK. Like Trina Solar, LDK's shares are trading near an all-time low; the share price has fallen 50.0% in the past year.

Analysts anticipate third-quarter earnings for Canadian Solar Inc. (NASDAQ: CSIQ) to be a whopping 96.3% higher than a year ago, or $0.54 per share on revenues of $248.0 million (+154.5%). The company easily topped estimates in the previous quarter. ReneSola Ltd. (NYSE: SOL) and Suntech Power Holdings Co. Ltd. (NYSE: STP) are also expected to report earnings growth of 29.7% ($0.37 per share) and 23.8% ($0.42 per share), respectively. All three of these stocks reached 52-week lows last week, and all are considered buys.

Rival home improvement chains Home Depot Inc. (NYSE: HD) and Lowe's Companies Inc. (NYSE: LOW) are scheduled to report quarterly results this week. Not surprisingly, given the ongoing housing slump, analysts surveyed by Thomson Financial on average expect both companies to post earnings lower than in the same period a year ago. For Home Depot, that's 61 cents per share, down 20.8%, and for Lowe's, 56 cents per share, down 16.4%. Meanwhile, cabinet maker American Woodmark Corp. (NASDAQ: AMWD), for whom Home Depot and Lowe's are major distributors, is also expected to report lower earnings: 11 cents per share, down 67.6%.

The presidential campaigns have prompted much discussion of energy policy and alternative energy sources. Some solar-energy-related concerns are scheduled to report this week, and expectations seem to be high. Trina Solar Ltd. (NYSE: TSL) is expected to report 81 cents per share earnings, up 67.9%; ReneSola Ltd. (NYSE: SOL) is expected to post earnings of 32 cents per share, up 62.5%; and Suntech Power Holdings Co. (NYSE: STP) is expected to have earnings of 32 cents per share, up 21.9%. Even China Sunergy Co. Ltd. (NASDAQ: CSUN) is expected to have swung to a profit of 3 cents per share, from a per-share loss of 14 cents a year ago.

MOST NOTEWORTHY: British Sky Broadcasting, ReneSola and Chordiant Software were today's noteworthy initiations:

• Jefferies believes British Sky Broadcasting's (NYSE:BSY) exposure to discretionary household expenditure seems more dangerous than it is. Shares were initiated with a Buy rating.
  
• Oppenheimer assumed ReneSola (NYSE: SOL) with a Perform rating and said it is waiting for margins to re-accelerate before becoming more constructive on shares.
  
• Chordiant Software (NASDAQ: CHRD) was initiated at B. Riley with a Buy rating and $7 target and believes the recent sell-off is overdone.

OTHER INITIATIONS:

• JMP Securities initiated American Capital (NASDAQ:AGNC) with an Outperform rating and $23 target.
  
• UBS assumed Omnicom Group (NASDAQ: OMC) and Interpublic Group (NYSE: IPG) with Neutral ratings and targets of $50 and $9.50, respectively.
  
• Real Goods Solar (NASDAQ: RSOL) was assumed at Broadpoint with a Buy rating and $10 target.

MOST NOTEWORTHY: Weyerhaeuser, Infineon and Intuit were today's noteworthy downgrades:

• Deutsche Bank downgraded shares of Weyerhaeuser (NYSE: WY) to Hold from Buy following the company's investor day, as they were disappointed that no REIT conversion will occur before 2010. Deutsche lowered their target price to $65 from $95.
  
• Citigroup assumed coverage of IFX (NYSE: IFX) and downgraded the stock to Hold from Buy on valuation following the recent rally.
  
• Merrill Lynch cut Intuit (NASDAQ: INTU) to Underperform from Neutral. The rating changes reflect Merrill's new rating system based on relative recommendations within the sector.

OTHER DOWNGRADES:

• Morgan Stanley lowered ReneSola (NYSE: SOL) to Underweight from Equal Weight.
  
• RBC Capital downgraded Canadian Pacific (NYSE: CP) to Sector Perform from Outperform.
  
• Praxair (NYSE: PX) was downgraded at HSBC to Neutral from Overweight.

Over the past few months, solar stocks have had more than their fair share of ups and downs. Last month, they were so volatile it seemed as if I was writing an article about another solar play every other day, introducing investors to the sector by casting the characters in a fictional movie to be called Solar's Eleven, encouraging buying on breakouts in this article, and warning investors to drop them as if they were poorly selling music artists in this article. (Yes, I go over the top sometimes, but it's all to help you better understand how the stock market works.)

I know buy and hold investors don't understand how I can change my mind so quickly about the same companies, but as you can tell from the charts of stocks like Evergreen Solar (NASDAQ: ESLR), Solarfun (NASDAQ: SOLF), DayStar Technologies (NASDAQ: DSTI), Akeena Solar (NASDAQ: AKNS), Canadian Solar (NASDAQ: CSIQ) and China Sunenergy (NASDAQ: CSUN), remaining nimble is key to profiting from this sector's volatility. In fact, only JA Solar (NASDAQ: JASO) and MEMC Electronic Materials (NYSE: WFR) have managed to hold near their highs.

So, what changed? Perception. While these companies all still have great potential, they are speculative and in bear markets, speculative stocks, especially those that don't continuously put out spectacular news, get crushed -- as shareholders in Apple (NASDAQ: AAPL), Baidu.com (NASDAQ: BIDU) and VMware (NYSE: VMW) have learned the hard way.