Maryland will increase the amount of electricity that suppliers must obtain from renewable energy sources after the state’s General Assembly voted to override the Republican governor’s veto of a renewables mandate.

Gov. Larry Hogan cited concern about the impact on ratepayers when he vetoed bills (S.B. 921/H.B. 1106) that will boost the level of required renewables to 25 percent of retail electricity sales by 2020, up from the current mandate of 20 percent by 2022.

Under the Maryland Constitution, bills enacted over the governor’s veto take effect 30 days after the override vote, which occurred...