Despite posting a third-quarter profit that beat analyst expectations and raising its full-year revenue forecast Friday, solar-cell maker JA Solar's stock took a 21.64-percent nose dive.

The Chinese company (NSDQ: JASO) reported its net income jumped to $22.1 million, or 47 cents per American Depository Share (ADS), from $553,135, or 2 cents per ADS, during the same quarter last year. Each ADS represents three common shares.

Analysts were expecting to see net income of 36 cents per ADS.

JA Solar also raised its revenue expectation for the full year of 2007 by about $20 million, to $320 million.

The company now expects its production capacity to reach 425 megawatts annually by the end of 2008, compared with its current 175-megawatt production capacity.

Still, Wall Street sent JA Solar shares down $15.04 Friday to close at $54.51 per share.

Nick Perry, an equity analyst for Schaeffer's Investment Research who writes for the Trading Floor Blog, said this might be a situation where short-term expectations became too lofty.

His conclusion comes after investors responded favorably to impressive earnings posted by thin-film solar manufacturer First Solar (NSDQ: FSLR) on Thursday.

First Solar shares jumped 34.3 percent from Wednesday's closing price to close at $224.43 per share Thursday after the company announced an increase in third-quarter profit and an improved 2007 sales outlook following plans to expand production (see Thin Film Solar Gets Another Boost, Thin-Film Solar Production to Leap Forward).

"I think some may have thought that if First Solar could surge after their report, then it was reasonable to expect the same type of move out of JA Solar," Perry said.

As a result, Perry said, investors raised the bar on company expectations to an unrealistic level.

"While the report looked solid, it wasn't the blowout that needed to be there," he said.

Perhaps investors shouldn't read too much into the day's events, he said. "The stock is still sitting verynear its all-time highs and is poised to show a small gain on the week."

Not bad considering that many Chinese stocks have been taking a hit.

Chinese solar companies, along with other new entrants, have struggled with high prices for the solar-grade silicon used to make solar panels (see Could China Steal the Solar Throne?).

And allegations of silicon-inventory discrepancies at LDK Solar (NYSE: LDK) have raised concerns about the quality of solar material coming from China (see New Details Surface as LDK's Stock Continues to Plunge, China Sunergy Snags Silicon).

Lower share prices could be an indication that investors fear JA Solar might suffer from some of the same issues in spite of solid third-quarter earnings.

In a research note Friday, Goldman Sachs analyst Cheryl Tang wrote that JA Solar is "unlikely to sustain" margins next quarter as some of JA Solar's customers start making their own solar cells.