UPDATE 1-SSE scales down Clyde wind farm in Scotland

(Adds details, SSE spokeswoman)

LONDON, July 1 (Reuters) - Scottish & Southern Energy PLC (SSE.L) said on Wednesday it was scaling down capacity by around 100 megawatts at its Clyde wind farm in southern Scotland, one of Europe's largest onshore wind farms.

SSE said the wind farm will have a total capacity of 350 MW, instead of 456 MW initially planned.

"Nevertheless, the design of the turbines, and their on-site configuration, mean the annual output of the wind farm, expected to be over 1,000 GWh, will be unaffected," it said.

"The construction cost, however, will be reduced to around 500 million pounds ($822 million)."

Last year, SSE was granted planning permission for the project, which was to cost about 600 million pounds and to comprise 152 turbines.

A spokeswoman at SSE said the change at the Clyde farm, one of Europe's largest onshore wind farms, would bring better returns as costs would be around 75 pounds per megawatt hour.

Germany's Siemens (SIEGn.DE) was likely to supply the 2.3 MW turbines, she added.

The wind farm was to be completed in 2012. (Reporting by Nao Nakanishi, Editing by Peter Blackburn)