First Solar Inc. (NSDQ: FSLR) shares rose a whopping 24.5 percent Thursday after several analysts upgraded their ratings on the stock.

Merriman and Soleil Securities both upgraded their ratings to "Buy" following better-than-expected earnings earlier this week, as well as announcements of several new supply deals.

The company posted a 54 percent jump in third-quarter profit Wednesday to $99.3 million, or $1.20 per share, compared with $46 million, or $0.58 per share, in the same period a year ago. The Tempe, Ariz., company also posted a third-quarter revenue of $348.7 million, up 54.4 percent from $159 million in the year-ago period (see First Solar Profits Up 54%, Credit Crunch Could Impact Biz).

Analysts expected earnings of just $1.01 per share on revenue of $339.3 million, according to Thomson Reuters.

The earnings report came with news that First Solar also had invested in SolarCity and would supply panels to the residential solar installer, marking First Solar's first residential customer agreement.

In addition, the company Thursday announced it has signed a long-term deal to sell panels to Sorgenia Solar, a developer of large solar power plants in Italy, and extended supply agreements with several existing customers, including EDF Energies Nouvelles, Ecostream, Juwi and Phoenix Solar AG.

Combined, the new agreements announced Thursday expand First Solar's sales contracts by 525 megawatts worth of panels from 2009 to 2013 and would be worth approximately $800 million at an exchange rate averaging $1.15 for €1 during that time.

"With strong market growth in Italy we are pleased to announce our new partnership with the Italian utility company Sorgenia Solar, who is well-positioned to develop solar-power plants in this important region," First Solar CEO Mike Ahearn said in a written statement. "These new module supply agreements and contract extensions enable our partners to increase solar-electric generation in multiple markets throughout Europe."

In a research note, Lazard Capital Markets analyst Sanjay Shrestha wrote that he views First Solar as "attractive" for medium- to long-term investors, but warned that trading will likely remain volatile in the near term.

"First Solar remains a core holding in our opinion given its cost leadership, manufacturing excellence, and strong balance sheet position," he wrote. "Risks include any unanticipated issues with capacity ramp, long-term contracts, or the macro/energy environment."

The company's stock price rose $28.32 per share Thursday to close at $144.07 per share.

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