TAMPA, Fla. — A Maryland woman and neo-Nazi leader with Florida connections are facing charges after federal authorities say they spent months plotting an attack on a power grid in Baltimore.

None are connected to the power grid. The homes in this subdivision—a diverse mix of multimillion-dollar homes and shacks—are powered by solar panels, wind turbines, and backup generators.

To make sure the grid can serve all of these customers, they need to make sure that power plants are operational and meeting all of the demand. When demand increases, these companies may have to ...