FRANKFURT, Feb 7 (Reuters) - Siemens Energy swung to a 1.58 billion euro ($1.7 billion) net profit in the first quarter, citing a one-off gain related to the sale of an Indian affiliate to former parent Siemens AG.

"The solid first quarter is encouraging, in part also due to project shifts, which are normal in plant engineering, especially with the market dynamics we are currently seeing," CEO Christian Bruch said.

"That is why our focus remains on solving the quality problems in our onshore wind business and making the most of the growth potential for the rest of the company."

($1 = 0.9301 euros) (Reporting by Christoph Steitz; editing by David Evans)