The rapid deployment of electric vehicle (EV) charging infrastructure in the C&I sector presents significant challenges in managing contracted power. BESS acts as an energy buffer, enabling the deployment of efficient and cost-effective fast and ultra-fast (DC) chargers without the need to oversize the grid connection infrastructure.
Alexandre Morant, Renewable Energy Product Manager at Vector Energy
Article published in issue 254 of Energética21 magazine
The challenge of power and demand charge management in C&I
Fleet electrification and the installation of charging hubs in C&I environments face a key challenge: the instantaneous power demand of high-capacity DC chargers. The peak demand generated by ultra-fast charging can far exceed the installation’s contracted power, resulting in:
Penalties: Additional costs for excess power under the Spanish tariff framework.
Infrastructure CAPEX: The need to request a costly and time-consuming expansion of the electrical connection, leading to higher fixed access tariffs and a significant initial investment.
BESS solves this problem by acting as a “virtual charging station.” The system decouples the EV’s charging power from the power drawn from the grid, allowing the company to optimize demand charging (the cost of contracted power) and the use of its point of connection (POC).
The BESS operation: Dynamic Peak Shaving to mitigate power spikes
The application of dynamic peak shaving is the most immediate economic benefit of the BESS. Its purpose is to limit the maximum grid power draw.
Monitoring and EMS: The Energy Management System (EMS) is the brain of the system, monitoring the net grid power draw and the power demanded by the chargers (OCPP protocol).
Hybrid Supply: When the combined demand (vehicle + chargers) approaches the contracted limit, the EMS calculates the deficit and instructs the BESS to discharge at a C-Rate sufficient to cover the need (power discharge rate). EV charging is fast and uninterrupted, while the installation’s grid consumption remains stable and below the penalty threshold. The BESS, which recharges slowly from the grid during off-peak hours (P3) or with PV production in self-consumption installations, manages instantaneous power, optimizing fixed and variable costs.
Technical Sizing and Energy Arbitration
Proper sizing ensures profitability and functionality:
BESS Power (kW): Must be at least equal to the difference between the maximum power of concurrent chargers and the target contracted power.
BESS Capacity (kWh): Sized to cover the duration of expected peak periods, depending on the fleet’s usage pattern.
Additionally, the BESS facilitates price arbitrage within the Spanish tariff framework: it stores energy from the grid during off-peak hours (minimum cost) or from rooftop PV systems, and injects it into loads during peak hours. This arbitrage strategy, combined with peak shaving, accelerates the Return on Investment (ROI) of the BESS.
BESS as an Enabler of Smart Mobility and V2G
The BESS is not just a battery; it’s a key element in active fleet management and smart charging.
PV integration and green charging: The BESS allows for the storage of surplus solar energy and prioritizes its use for EV charging. This makes it easier for companies to meet their sustainability and carbon footprint reduction goals by maximizing “direct green charging.”
Vehicle-to-Grid (V2G) and captive fleets: The BESS is the first step towards V2G. In captive fleets (logistics, buses, etc.), the BESS and vehicles can operate in a coordinated manner. When parked and with sufficient battery capacity, vehicles can feed energy back to the BESS or the C&I installation during periods of high demand or high prices. Although V2G regulations are still being developed in Spain, the bidirectional capability of the BESS and V2G-ready chargers lays the groundwork for this future fleet monetization. The integration of BESS solves the most pressing problem in EV infrastructure deployment in the C&I sector: power limitations. BESS systems are becoming essential for the technical and financial viability of fleet electrification.
Looking ahead, these storage assets will not only benefit individual companies but will also be integrated into the global electricity grid. BESS in C&I, through demand aggregators, will be able to offer flexibility services to the grid (such as frequency or voltage regulation), transforming the charging hub into a distributed resource and opening a new revenue stream for the Spanish C&I sector.
Learn more about BESS storage solutions from SUNVEC Storage