Behind-the-meter residential electric vehicle smart charging strategies: Danish cases

This paper presents and compares electric vehicle (EV) smart charging (SC) strategies for residential customers with a photovoltaic (PV) system. Three SC strategies are designed with a focus on user interests, the vehicle charges depending on (1) spot price and time-of-use (ToU) tariffs, (2) prognosis for grams of emission per kWh, and (3) own PV production. All strategies consider a local virtual aggregator, which collects information regarding price and emission prognosis, power flow at the household meter, EV connection time, time availability, and EV-user charging needs. Based on a survey of EV Danish owners, three charging patterns are identified and used to compare the effect of varying the charging flexibility within the aforementioned SC strategies. The results show that strategies with regard to price and emission signals are able not only to provide a positive impact on their own specific goal but also to reduce both costs and CO2 emissions. However, this is highly dependent on the connection time of EVs, where overnight charging and more frequent EV connection increase the strategies effect. Charging based on own PV production requires greater user awareness with respect to connection times to have a noticeable effect. However, when the EV is connected during sunny hours, there is good potential for self-consumption increase.