Energy storage through water heaters to support renewables in residential segments

Abstract

Residential segments are gaining momentum from the point of view of Demand-Response. Main end-uses in this segment such as Water Heating, Electrical Heating or Cooling can modulate, at some extend, their service to offset a change in generation through and increase or decrease of demand. This enables an adaptation of demand to the volatility of Renewable Energy Sources and, moreover, satisfy some requirements during network constraints. Due to the volatility of renewables and the changing requirements of networks, it seems difficult to plan the management of demand through “black box” models. The alternative of “grey box” approaches appears as more suitable than other methods. For instance, Physical-Based Methodologies, can achieve a more accurate control of demand, while monitoring state variable changes on loads, and surveying comfort thresholds. The aim of this paper is the reformulation of an elemental Water Heater model (including Heat Pump technologies) that makes easier the participation of these loads in complex products through aggregation. In some countries (Spain or Italy), the size of residential units is smaller than in the USA, Canada or France, and this capacity conditions control and energy storage. In this way, the possibility of load performance as a responsive resource or as a storage element (sometimes cheaper than electrical storage) achieves an interesting potential for the coordination of demand with renewables. Simulation results demonstrate that this coordination can be improved using these ‘grey models’ to reduce or mitigate the volatility of renewables without inducing a noticeable customer discomfort. Simulation results show that self-generation can increase from 15 to 35% in a representative residential scenario.