* LDK Solar drops more than 18 percent
* Barclays downgrades U.S. solar energy sector to neutral
* Analysts upgrade, raise target price for JA Solar
(Adds details on JA Solar)
NEW YORK, Aug 13 (Reuters) - U.S. solar power company shares fell on Thursday, led by an 18-percent drop in LDK Solar Co Ltd LDK.N, which posted a wider-than-expected quarterly loss.
The slump came as Barclays Capital downgraded the U.S. solar energy sector to "neutral" from "positive," as it sees slowing growth in demand and recommended that investors wait for better entry points.
And in Germany, Q-Cells AG QCEG.DE, one of the world's largest solar cell makers, said it would slash its workforce by about a fifth as a result of a price slump in the industry that caused a first-half loss before interest and tax.
"Although solar shares have underperformed so far, we believe lack of potential near-term catalysts, relatively rich valuation and weak seasonality could likely result in further downside pressure," Barclays analyst Vishal Shah wrote in a note to clients.
In trading on the New York Stock Exchange, LDK Solar's stock was down $2.06, or 18.38 percent, at $9.15.
China's Yingli Green Energy Holding Co Ltd (YGE.N) was down 8.25 percent to $12.35, Suntech Power Holdings Co Ltd STP.N fell 7.19 percent to $17.03 and Trina Solar Ltd TSL.N fell 8.69 percent to $27.22.
On the Nasdaq, First Solar Inc (FSLR.O) was down about 60 cents at $144.39 and Sunpower Corp SPWRA.O slipped 44 cents to $28.32.
Still, some analysts saw a few sunny rays. Analysts at Simmons and Co upgraded Chinese solar company JA Solar Holdings Co Ltd (JASO.O) to "neutral" from "underweight" and Credit Suisse raised the target price of the company's stock to $4 from $3.
JA Solar's stock was down more than 8 percent to $4.09 on the Nasdaq on Thursday, a day after it posted a quarterly net loss. (Reporting by Steve James in New York and Laura Isensee in Los Angeles. Editing by Gerald E. McCormick and Robert MacMillan)