A Ljubljana demonstration tested automated scheduling for electric-vehicle charging using day-ahead electricity-price signals while maintaining vehicle charging requirements. The trial involved Avant Car and Kolektor sETup, with optimisation shifting charging into lower-cost periods. Results from the two-month programme were reported as narrowing the gap between actual charging costs and a theoretical least-cost scenario.
Ljubljana trial results for price-optimised charging
The two-month trial used automated scheduling to move EV charging into lower-cost electricity periods while keeping charging requirements met. It covered six charging stations and relied on day-ahead electricity-price signals to determine when vehicles should charge. Before optimisation, actual charging costs were reported at 18.9% above the theoretical least-cost scenario.
During the demonstration, the reported gap fell to 5.99%, described as an improvement of around 68% in alignment with the cheapest available charging periods. The project’s focus was primarily on day-ahead price optimisation, including shifting charging sessions towards less expensive periods, particularly after midnight. The demonstration reported that automated optimisation materially narrowed the difference between actual charging cost and the theoretical optimum.
Charging flexibility as an actively managed portfolio
The reported commercial significance extends beyond cheaper electricity. EV fleets were described as combining characteristics that can be valuable to power systems: large electrical loads, predictable periods when vehicles are connected, and flexibility over when charging occurs. A vehicle may need a certain amount of electricity before its next journey, but it was stated that it rarely needs to consume every kilowatt-hour immediately after plugging in.
The hours between connection and departure were described as a flexibility window that software can monetise. A fleet-management platform can determine which vehicles need immediate charging, which can wait, and how much aggregate consumption can be moved between different electricity-market periods. Charging was characterised as becoming an optimisation problem rather than a simple transaction between charger and vehicle.
Implications for electricity procurement and grid operations
For fleet operators, the immediate benefit described is reduced electricity cost. For aggregators and electricity suppliers, the larger opportunity described is combining hundreds or thousands of chargers into a controllable portfolio. A fleet with hundreds of vehicles was stated to have potential to move several megawatts of electricity demand from one period to another without changing the transport service delivered to customers.
The source material linked this to relevance for energy procurement and, eventually, demand response, balancing and local flexibility markets. It also highlighted a potential issue at larger scale: if thousands of vehicles receive the same price signal and move charging into the same cheap hour, the result could be a new demand peak. It was stated that what is optimal for consumers may not be optimal for the network.
Signals for smart charging beyond time-of-use tariffs
The source material described next-generation smart charging as more sophisticated than simple time-of-use tariffs. Charging algorithms were said to increasingly need to consider at least two signals simultaneously: the wholesale price of electricity and the physical condition of the local network. A third signal was described as potentially coming from balancing or flexibility markets.
An EV fleet could then respond differently depending on which service has the highest value. The material described scenarios where a fleet could charge aggressively during an hour when wholesale electricity is inexpensive, reduce charging later to relieve a distribution constraint, or alter demand when a system operator needs balancing flexibility. This was described as turning a charging portfolio into a virtual power-system asset.
Fleet management models and infrastructure procurement
The business model was described as particularly attractive for centrally managed fleets. Car-sharing operators, delivery companies, municipal fleets, taxis, corporate vehicles, buses and logistics companies were said to typically have better information about vehicle schedules than individual residential customers. That information was described as making charging flexibility easier to forecast.
A fleet operator was described as often knowing which vehicles must leave at 06:00, which will remain parked until noon, and how much energy each one requires. An optimiser can use those constraints to determine the cheapest or most valuable charging schedule automatically. The physical charger was described as only one part of the service, with more value potentially sitting in software controlling thousands of chargers.
Scaling considerations and bidirectional charging context
The source material stated that Slovenia’s demonstration remains small compared with the scale required for a liquid national flexibility market. It also reported that smart charging of a shared fleet can materially reduce the gap to optimal charging costs under real operating conditions while noting that scaling is the larger opportunity now identified. It further stated that unmanaged EV charging risks becoming another source of peak electricity demand as EV adoption grows.
The material described managed fleets as offering an opposite possibility by treating electric vehicles as one of its largest controllable loads instead of becoming a burden on the grid. Vehicle-to-grid technology was mentioned as potentially extending opportunities by allowing electricity to flow back from EV batteries, but it stated that bidirectional charging is not necessary for the first stage of the market. It concluded that simply controlling when vehicles consume electricity already creates substantial flexibility.
The value proposition for electricity companies and fleet operators was described as including not only kilometres travelled but also flexibility created during hours when vehicles are standing still.