* Q3 sales 1.17 bln eur vs 1.19 bln Reuters poll
* Q3 EBITDA 168 mln eur vs 192 mln Reuters poll
* Still sees 2013 sales of about 4.5 bln eur, lower EBITDA
* Shares indicated 3.1 percent lower (Recasts, adds details on polysilicon business, shares)
FRANKFURT, Oct 31 Wacker Chemie's third-quarter core earnings plunged by nearly a fifth, hit by low prices for polysilicon, a key material it supplies to the crisis-ridden solar industry.
Wacker Chemie - the world's No.2 maker of polysilicon, used in solar cells - said its earnings before interest, tax, depreciation and amortisation (EBITDA) came in at 168 million euros ($231 million) in the third quarter.
Analysts had, on average, expected third-quarter EBITDA of 192 million euros.
"The prices for solar silicon remain a challenge. They were about one-third lower than a year ago," Chief Executive Rudolf Staudigl said in a statement on Thursday.
Wacker kept its outlook for the current year for sales of about 4.5 billion euros and a drop in EBITDA.
Through its polysilicon business, which accounted for nearly a third of nine-month core earnings, Wacker depends on the solar industry, where oversupply of cells and modules and falling government support has pushed a large number of sector players into insolvency.
Polysilicon prices have plunged to below $20 per kg from a 2008 peak of almost $400, squeezing Wacker Chemie as well as major rivals Hemlock Semiconductor and Norway's Renewable Energy Corp, triggering those in the sector to cut jobs or reduce capacity.
Sector leader Hemlock Semiconductor, a joint venture between Dow Corning and Shin-Etsu Handotai, in January announced it would cut 400 jobs.
Wacker Chemie also competes with Mitsubishi Materials , as well as Korean OCI Co Ltd and China's GCL-Poly Energy Holdings.