SPRING HILL, Tenn. (AP) — General Motors plans to buy enough solar energy to power its Tennessee assembly plant by late 2022. The automaker announced Thursday that its agreement at its Spring Hill plant with the Tennessee Valley Authority is expected to provide up to 100 megawatts of solar energy annually, the amount used by 18,000 U.S. households each year. A solar farm in Lowndes County, Mississippi, currently under development by Origis Energy will provide the energy. GM says the move should increase its sourced electricity to more than 50% renewable by 2023, moving it closer to its goal of 100% in the U.S. by 2030 at GM-owned sites. The Spring Hill investment is part of the Tennessee Valley Authority's Green Invest program, which involves long-term agreements to buy and claim new renewable energy.