Load balancing: how to deploy 50 charging stations without an EDF upgrade

Dynamic load balancing is the key technology that allows companies to deploy IRVE charging stations on a massive scale without changing their power contract with Enedis. In practical terms, it is what separates a successful project from an electricity bill multiplied by three.

What is load balancing in EV charging (IRVE)?

Load balancing — or dynamic power distribution — is a software mechanism that controls in real time the electrical power delivered to each charging station on a given site. Unlike a conventional installation where each station has a fixed, unchanging power level, load balancing continuously adapts the allocation based on:

• the number of vehicles plugged in simultaneously
• the residual power available on the building's main distribution board
• the configured priorities (fleet > employees > visitors, for example)
• the time slots defined by the operator

The goal is simple: never exceed the power subscribed from Enedis, whatever the conditions of use of the car park.

How does load balancing work with Spark Pilot?

Spark Pilot, Sparklin's supervision platform, includes a load balancing module natively. Its operation relies on three components:

1. The main power sensor

A telemetry sensor (or a Linky smart meter) is installed on the building's main distribution board. It reports in real time the power consumed by the entire site — heating, lighting, lifts, IT equipment. Spark Pilot thus has a precise view of the power available for charging at any given moment.

2. Real-time distribution calculation

Every 30 seconds (configurable), Spark Pilot recalculates the power allocated to each active charging station. The algorithm applies the rule: available charging power = subscribed power − current building consumption − safety margin. This power is then distributed across all charging stations according to the configured priorities.

3. OCPP 2.0.1 communication

Sparklin charging stations (Spark 1, Spark Plus) communicate with Spark Pilot via the OCPP 2.0.1 protocol. It is this channel that allows the platform to send power setpoints in real time, and the charging stations to report their actual consumption instantly. End-to-end latency is below 500 ms.

Real-world example: 50 charging stations on a 200 kVA site

Let's take a real-world example of a Sparklin deployment at an industrial client in the Île-de-France region:

In practice, on this site, no more than 22 vehicles ever charge simultaneously at full power (simultaneity rate: 44%). Spark Pilot distributes the available 200 kVA across these 22 active charging stations, guaranteeing an average of 9 kW per vehicle — a full charge in under 5 hours for most fleet vehicles.

What is the impact on the electricity bill?

The professional electricity bill in France (HTA tariff or BT > 36 kVA) breaks down into two main components:

• The energy component: the cost of the kWh actually consumed — this component mechanically increases with EV charging, but in a predictable and controlled way.
• The power component (fixed charge): the cost of the power subscribed from Enedis. This is where load balancing makes all the difference.

Without load balancing, a company deploying 30 charging stations of 7.4 kW often has to increase its subscribed power from 100 to 180 kW — which translates into a rise in the annual fixed charge of €8,000 to €14,000, regardless of actual consumption.

With Spark Pilot, this increase is nil or marginal. The ROI of the Spark Pilot subscription (from €1,200/year for a site) is generally achieved in 3 to 6 months through the power-component savings alone.

Static vs dynamic load balancing: what's the difference?

There are two approaches to load balancing, with very different performance:

Static load balancing

The maximum power is divided by the total number of charging stations and assigned on a fixed basis. Example: 100 kW / 20 stations = 5 kW per station, permanently, whether or not cars are plugged in. Simple to implement, but very inefficient: unoccupied stations "lock up" power needlessly.

Dynamic load balancing (Spark Pilot)

Power is distributed only among the active charging stations, in real time. If only 8 of 20 stations are occupied, each receives 100/8 = 12.5 kW instead of 5 kW. Vehicles charge 2.5 times faster for an identical overall cost. This is the standard adopted by Spark Pilot and required by the OCPP 2.0.1 standard.

LOM regulatory requirements and load balancing

Since the LOM decree 2021-1246, any IRVE deployment on a car park with more than 10 spaces must include energy management to prevent power overruns. In practice, this requirement translates into an obligation to deploy a load balancing system as soon as several charging stations share the same power supply.

From July 2026, DREAL inspections will be active and may impose fines of up to €75,000 per non-compliant car park. A car park equipped with charging stations but no smart control therefore exposes its operator to a double risk: financial (Enedis overruns) and regulatory (LOM fines).

Checklist before deploying your charging stations

Before launching an IRVE project, here are the questions to ask yourself in order to assess your load balancing needs:

1. What is your site's current subscribed power? (on your EDF/Enedis bill, in kVA or kW)
2. What is the building's current peak power? (ask your technical facility manager)
3. How many charging stations do you plan to deploy? and at what unit power?
4. What is the estimated simultaneity rate? (generally 30 to 50% in a company car park during the day)
5. Are there predictable consumption peaks on your site (employees arriving in the morning, leaving in the evening)?

If the combined power of the charging stations exceeds 50% of your subscribed power, dynamic load balancing is essential. Sparklin offers a free power audit that answers all these questions within 48 hours.