Exhibit 21-A

OTTER TAIL CORPORATION

Subsidiaries of the RegistrantMarch 2, 2015

Company	State of Organization
Otter Tail Power Company		Minnesota
Otter Tail Energy Services Company, Inc.		Minnesota
Green Hills Energy, LLC		Minnesota
Sheridan Ridge I, LLC		Minnesota
Sheridan Ridge II, LLC		Minnesota
Otter Tail Assurance Limited		Cayman Islands
Varistar Corporation		Minnesota
Northern Pipe Products, Inc.		North Dakota
Vinyltech Corporation		Arizona
T.O. Plastics, Inc.		Minnesota
IMD, Inc.		North Dakota
6472702 Canada, Inc.		Ontario, Canada
BTD Manufacturing, Inc.		Minnesota
Miller Welding & Iron Works, Inc.		Minnesota
Shrco, Inc.		Minnesota
Galva Foam Marine Industries, Inc.		Missouri
SLI, Inc.		Minnesota
ASI, Inc.		Minnesota
Aevenia, Inc.		Minnesota
Foley Company		Missouri