* Cuts 2014 shipment forecast to 3.6-3.8 GW from 4-4.2 GW
* Expects lower selling prices in second half
* Q2 adj loss/share $0.26 vs est of $0.14
* Revenue $549.5 mln vs est $588 mln
* Shares fall as much as 9.6 pct (Adds executive and analyst comments, details, background; updates share)
By Shubhankar Chakravorty
Aug 27 (Reuters) - Yingli Green Energy Holding Co Ltd reported a bigger-than-expected quarterly loss and cut its forecast for 2014 panel shipments, faced with steep U.S. duties.
Shares of Yingli, the world's biggest solar panel maker by volume, fell as much as 9.6 percent in morning trading.
The company, whose panels powered the Maracana stadium in Brazil during the 2014 Fifa World Cup final, said it now expects to ship 3.6-3.8 gigawatts (GW) of panels this year, down from its earlier forecast of 4-4.2 GW.
Yingli expects the United States to account for only a tenth of total shipments this quarter, down from a quarter in the first quarter ended March.
The company faces a combined U.S. tariff of 42.33 percent, much higher than the industry average of about 31 percent. Tariffs vary depending on the U.S. Department of Commerce's evaluation of a company "dumping" practices.
The United States extended duties on China-made solar products to those made in Taiwan last month, after several Chinese solar companies moved manufacturing there.
Demand was robust in China, where shipments doubled in the second quarter from the first.
China is going to be a very important market for Yingli's shipment growth, S&P Capital IQ analyst Angelo Zino said.
But margins would likely shrink if Yingli relies too much on the domestic market, where prices are among the lowest globally.
Chief Financial Officer Yiyu Wang said he expected average selling prices to fall in the second half of the year from second-quarter levels.
The company, which has lost money in 12 quarters in a row, said it was opening offices and expanding in South America, Europe, Japan and the United Kingdom.
The company forecast shipment of 900-1,000 MW for the third quarter ending September. It shipped 887.9 MW in the second quarter ended June 30 - up almost 41 percent from the first.
Overall gross margin increased to 15.6 percent from 11.8 percent a year earlier, helping narrow net loss to $46 million, or 26 cents per American depositary share (ADS), from $52.3 million, or 33 cents per ADS.
Excluding items, it posted a loss of 26 cents per ADS.
Revenue fell to $549.5 million from $550.4 million.
Analysts on average had expected a loss of 14 cents per share on revenue of 588 million, according to Thomson Reuters I/B/E/S.
Baoding-based Yingli's shares were down 4.5 percent at $3.40, after touching a low of $3.22, on the New York Stock Exchange on Wednesday. They had fallen 18 percent in the 12 months through Tuesday. (Editing by Joyjeet Das)