Minnesota tribe built solar for its casino. Now its electric supplier vows to cut off power.

A Dakota tribe in western Minnesota plans to turn on a new solar array as soon as next month to help power its casino and hotel.

But if the Upper Sioux Community follows through on that plan, the local electric provider says it will disconnect the tribe’s gaming enterprise from the grid, leaving the tribe without enough energy.

The unusual conflict between Upper Sioux and Minnesota Valley Cooperative Light and Power Association has pitted assertions of tribal sovereignty against claims the project flouts state utility laws.

That debate has now landed at the Minnesota Public Utilities Commission, after the tribe asked the board of utility regulators in early May to make Minnesota Valley keep the lights on.