UPDATE 1-Enel's SE sees 2010 prices 15-20 pct down

* Slovak market following German power prices

* Ups capacity at nuclear power plant Jaslovske Bohunice

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BRATISLAVA, Oct 20 (Reuters) - Market power prices in Slovakia will be 15-20 percent lower next year than in 2009, Slovenske Elektrarne (SE), a unit of Italy's utility Enel (ENEI.MI) (ENEI.MI), said on Tuesday.

Chief Executive Paolo Ruzzini said the Slovak market, linked with the Czech power market, was following German power prices.

"There is a conversion of Slovakia's and Czech (power) markets with the Germany's," Ruzzini told journalists on the sidelines of an energy conference, adding positive trends in commodity prices were another factor.

Slovakia runs a day-ahead spot power market in Slovakia, and the exchange has 16 market participants.

Power Exchange Central Europe (PXE), operated by the Prague Stock Exchange, offers power futures with physical settlement in the Czech Republic, Slovakia, and Hungary and spot contracts in the Czech Republic in cooperation with the state-owned market operator OTE.

Ruzzini also told reporters the company had increased capacity at its nuclear power plant Jaslovske Bohunice by 1.7 percent. The increase takes the overall available power output at the facility to 970 MW from 954 MW.

The Slovak power firm, which has already decommissioned two older blocks at Bohunice, aims to boost power capacity from its nuclear sites to 1,940 MW by 2010 compared with 1,760 MW in 2007.

Enel, which holds a 66-percent stake in Slovakia's major power utility, is currently finishing two further blocks at its second nuclear site in Mochovce. Slovenske Elektrarne operates 5,617.24 MW of gross installed capacity. (Reporting by Martin Santa; Editing by Jan Lopatka)