Understanding the Impact of Electric Water Heater Control on the Grid

Electric water heaters (EWHs) are common in Vermont and are currently being controlled on a small scale to minimize loads at peak times. This paper presents a framework for understanding how increasing the EWH control in areas like Vermont will impact the grid and the customer's experience. We report on a a case-study using on two Rutland, VT feeders with two different EWH control strategies, at multiple penetrations of EWH participation. We quantify the rebound, the implications on water temperature and customer satisfaction and, using a co-simulation framework, we also estimate the impact on the feeder voltage. Our results show that, with a large customer participation (75%), we can deduce the peak by as much as 25%, but there are trade-offs between customer satisfaction and the rebound effects on both energy use and voltage.