Domestic Heat-Pump Water Heater Aggregates: a Contribution to Demand Flexibility

In this paper, a method to quantify the flexibility of aggregates of domestic heat-pump electric water heaters for the provision of system services is proposed. Flexibility is defined as the capability of the aggregate to modify its power demand for a given time interval. The method uses the dynamical model of the water heaters and a stochastic model of ambient and cold water temperatures and hot water demand, combined in a Monte Carlo analysis. The case of large aggregates defined throughout the Italian territory has been studied.