Cost-effective optimization for electric vehicle charging in a prosumer household

Abstract

The operating expenditures of electric vehicles (EVs) consist mainly of the electricity used to charge the EV battery and of the replacement of wearing parts. This paper aims to optimize the EV battery charging as cost-effectively as possible for a household with a small-scale photovoltaic (PV) power plant. The optimization is carried out by problem-based optimization to closely match the average Finnish user behavior. For reference, an optimization was also performed disregarding the user behavior to make EV charging as cost-effective as possible. Cost minimization was done by using Nord Pool Spot market data to find the cheapest grid electricity prices, employing a perfect PV forecast, and using only surplus PV electricity for EV charging. Six years’ worth of data were analyzed, and it was found that the annual savings with average user behavior ranged between 25.4% and 51.9% when comparing optimized charging with uncontrolled charging. When disregarding the typical user behavior and having the EVs chargeable at all times, the annual savings ranged between 38.3% and 54.5%. The results show that the more the user uses the EV daily, the more cost-effective the optimization becomes compared with uncontrolled charging methods. The results also show that depending on daily fluctuations in the electricity prices, it is sometimes more beneficial to sell the produced PV power rather than use it to charge the EV and instead charge the EV with grid electricity at nighttime.