The energy grid is vastly more complicated than it was ten years ago. The old model was to plug in and pay for what you use, but now the grid is starting to ask for something back from consumers. This change is aimed at flatten the demand curve.
Think about how you use electricity: you wake up, turn on some lights, and maybe have a hot shower. After work you come home, cook some dinner, and watch TV. In the winter, maybe you heat with some kind of electric heat, or – even more likely – maybe in the summer you switch on AC.