** Shares of utility Talen Energy TLN.O fall ~1% to $229.22 premarket

** Co reports Q1 net loss of $135 million, compared with a profit of $294 million a year ago

** TLN says Q1 interest costs rose 25.4% to $74 million during the quarter, while total energy expenses rose 10.8% to $235 million

** Co to extend planned outage in Unit 2 of Susquehanna nuclear facility until mid-May to conduct incremental maintenance work

** As of last close, stock is up 14.8% YTD

(Reporting by Vallari Srivastava in Bengaluru)

((Srivastava.Vallari@thomsonreuters.com;))