Oklahoma residents who produce their own energy through solar panels or small wind turbines on their property will now be charged an additional fee, the result of a new bill passed by the state legislature and expected to be signed into law by Gov. Mary Fallin (R).

On Monday, S.B. 1456 passed the state House 83-5 after no debate. The measure creates a new class of customers: those who install distributed power generation systems like solar panels or small wind turbines on their property and sell the excess energy back to the grid. While those with systems already installed won’t be affected, the new class of customers will now be charged a monthly fee — a shift that happened quickly and caught many in the state off guard.

“We knew nothing about it and all of a sudden it’s attached to some other bill,” Ctaci Gary, owner of Sun City Oklahoma, told ThinkProgress. “It just appeared out of nowhere.”