Shifted or Additional Charging of Electric Vehicles? The Effect of Smart Charging on German Prosumers

Special smart charging modes are an energy service that enables prosumers to charge their electric vehicle exclusively with self-generated electricity. In this paper, we evaluate empirically how 39 prosumer households adjusted their charging behaviour after introducing this smart charging mode under real-life conditions in a field trial in Germany. With a panel-data regression strategy and rich set of household-level charging data, we test the following hypotheses: With the smart charging mode, prosumers charge (i) more during the midday PV peak (11am – 3pm), but (ii) their charging remains the same during off-peak hours (4 – 8pm). The smart charging mode led to changes in the participants' charging behavior that confirm the first part (i) of our hypothesis and partially the second part (ii). We find strong evidence of an increase during the midday peak by 16%. In line with our hypothesis, this shift was not offset by a corresponding decrease during off-peak hours. However, we identify a significant increase in the off-peak load during the treatment when we apply the morning load as a reference period. This intraday shift from the morning may be explained by a coincidence of participants’ presence at home and PV generation at the start of the off-peak hours (around 4pm). Overall, our results provide micro-level evidence that the introduction of smart charging based on PV production induces load shifting, but that the response is more complex than a mere shift from evening to midday.