How Many Charge Points Should You Install? Sizing an EV Charging Infrastructure

“How many charge points should we install?” is probably the first question a business, a homeowners' association or a local authority asks when facing a charging project. The answer is never a standard figure: it depends on the number of electric vehicles to serve, on their parking durations and, above all, on the power actually available on site. This guide sets out the method for sizing a charging infrastructure without over-investing or running out of room in the very first year.

Why correct sizing is decisive

Getting the sizing of a charging infrastructure wrong has a price in three ways, and all of them are costly in the long run.

The first risk is over-sizing: installing too many charge points, or power ratings that are too high, relative to actual usage. You then tie up capital in equipment that is rarely used, and sometimes trigger an upgrade of the Enedis grid connection that was not necessary. The second, symmetrical risk is under-sizing: too few charge points, queues, frustrated users who end up charging elsewhere. The third issue is compliance: depending on the type of building and the applicable regulations (notably the LOM law and its pre-equipment obligations), an under-specified project may fail to meet legal requirements.

• Control costs: invest in what is genuinely used, not in a power reserve that is never tapped.
• Ensure satisfaction: avoid usage conflicts and charge points that are permanently occupied.
• Stay compliant: cover the regulatory obligations specific to the building.

Correct sizing is therefore not an abstract calculation: it is the balance between a real need, an electrical constraint and a budget. It is built, not guessed.

The questions to ask before counting charge points

Before talking about equipment, you have to frame the usage. Three questions structure the entire approach.

How many electric vehicles to serve?

The starting point is the electric vehicle fleet to be supplied, today and tomorrow. A company fleet gradually switching to electric, a homeowners' association where a few residents go electric each year, a public local-authority car park: the trajectories are very different. You have to estimate the number of vehicles over the target horizon, not just the immediate need, or you will have to redo everything two years later.

What parking durations?

The same vehicle does not tie up a charge point in the same way depending on whether it is parked for eight hours or thirty minutes. The longer the dwell time, the more a single charge point can pool several sessions across the day, and the fewer charge points are needed for a given fleet. An office car park where cars stay all day does not have the same need as a fast-turnover transit zone.

What are the actual uses?

Convenience charging during the working day, essential charging for a fleet that heads out again in the evening, top-up charging for visitors: each use calls for a different logic. Identifying the dominant use shapes both the number of charge points and their power.

Site power: the real limiting factor

This is the point most often underestimated. People think first in terms of the number of charge points, whereas the decisive constraint is almost always the available electrical power on site and the level of the subscribed capacity.

Every charge point draws power. Plugging in several vehicles at the same time, at full power, can quickly exceed what the grid connection is able to deliver. Exceeding this limit means either tripping the installation, or asking Enedis for a grid connection upgrade — an operation that can be long and costly, sometimes the heaviest item in a project.

The real question is not “how many charge points can I buy?” but “how many charge points can my grid connection supply?”. This nuance changes the whole design: you size from the available power, not the other way round.

Before settling on a number of charge points, you therefore need to know the subscribed power, the margin actually available once the building's other uses are deducted, and the capacity of the grid connection. This electrical analysis is the foundation of sizing.

Dynamic load management: more charge points without an upgrade

Good news: the available power does not impose a rigid ceiling on the number of charge points. That is precisely the role of dynamic energy load management (load balancing), which radically changes the equation.

The principle is to distribute power intelligently between the charge points according to what the installation can deliver at any given moment, rather than allocating a fixed full power to each one. Since all the vehicles are never plugged in at 100% simultaneously, and since those parked for a long time do not need to charge at full rate continuously, you can supply far more charge points than a static split would allow.

• Distribute the available power between the plugged-in vehicles, without ever exceeding the site's capacity.
• Avoid an Enedis upgrade by staying below the threshold of the existing subscription.
• Prioritise certain vehicles when usage requires it (a fleet that has to leave early, for example).

In practice, dynamic load management often makes it possible to install several times more charge points than a rough calculation would suggest, without touching the grid connection. For a homeowners' association or a fleet set to grow, it is a decisive lever to factor in from the design stage.

AC or DC: choosing the power according to usage

The charging technology depends directly on the usage identified above. Two main families coexist.

Alternating current (AC) charging

The AC charge point, known as “slow” or “accelerated”, covers the vast majority of needs when vehicles are parked for a long time: company car parks, homeowners' associations, employee or resident spaces. It is simpler to install, more economical, and perfectly suited to charging spread over several hours. For a fleet that spends the day or the night on site, it is generally the right choice.

Direct current (DC) charging

The DC charge point, known as “fast”, delivers a much higher power and recharges in a shorter time. It makes sense for fast-turnover uses: a fleet that cannot keep its vehicles idle, a station open to the public, a top-up between two trips. In return, the equipment and the grid connection are significantly heavier and more expensive. Reserving it for cases where it is genuinely useful avoids over-investing.

The table below gives, purely as a guide and to be confirmed after an audit, an orientation logic by site profile:

Site profile	Parking duration	Typical orientation
Company / office car park	Several hours	AC, with dynamic load management
Residential homeowners' association	Full night	AC, scalable pre-wiring
Turnover fleet	Short	Enhanced AC or DC depending on the pace
Public reception / transit	Very short	DC depending on traffic

These orientations do not replace a study: the right trade-off depends on your site, your available power and your actual uses.

Planning for scalability: pre-wiring

An electric vehicle fleet rarely grows all at once. It rises in stages, as fleets are renewed or as residents go electric. Sizing for today while forgetting tomorrow is the classic mistake: you end up reopening the trenches and removing the walls two years later, at a much higher cost.

The remedy is pre-wiring (or pre-equipment). Rather than installing all the charge points straight away, you deploy the heavy infrastructure from the outset — cable trays, a dedicated panel, electrical provisions — so that adding charge points later comes down to a simple connection, with no structural work.

• Anticipate the fleet's growth over 3, 5 or 10 years.
• Reduce the cost of future additions by avoiding rebuilding the infrastructure.
• Limit disruption: no new heavy works with every expansion.

This scalable logic is in fact in keeping with the spirit of the regulations on car park pre-equipment: provide generously for the electrical provisions, equip the spaces gradually. It is almost always the most economical choice over the lifetime of the infrastructure.

Common sizing mistakes

Beyond the method, certain pitfalls come up regularly in poorly framed projects.

Over-sizing consists of multiplying high-power charge points “to be on the safe side”, without taking parking durations into account. The result: an inflated investment, a grid connection needlessly upgraded, under-used equipment. Conversely, under-sizing ignores fleet growth and rising usage: the charge points saturate quickly, users get discouraged, and the expansion costs more than a project properly thought through from the start.

Two other mistakes are common. Forgetting dynamic load management leads to wrongly concluding that the grid connection needs upgrading, when intelligent power management would have been enough. And neglecting pre-wiring turns every future addition into a full-scale worksite. In both cases, it is anticipation that is missing — exactly what a prior audit makes it possible to avoid.

The role of the Volticom audit

Everything above converges on a single point: correct sizing rests on an on-site audit, not on assumptions or generic ratios.

In concrete terms, the Volticom audit assesses the power actually available on your grid connection, measures the margins once the other uses are deducted, and cross-references this data with your vehicle fleet, your parking durations and your uses. From there, sizing becomes factual: the number and type of charge points (AC or DC), the power, and above all the integration of dynamic load management to multiply the charge points without triggering an Enedis upgrade.

The infrastructure is designed to be scalable from the outset, with pre-wiring that prepares for future expansions. Volticom, an IRVE installer based in Paris, works with the QUALIFELEC IRVE qualification, remote monitoring of connected installations, a decennial liability insurance policy with AXA, subject to the declared activities, limits and terms of the current insurance certificate and AXA insurance. The objective is simple: align the number of charge points with the reality of your site, no more, no less.

FAQ: sizing your charging infrastructure

How many charge points for X electric vehicles?

There is no reliable universal ratio: the right number depends on parking durations and on the available power. A fleet where vehicles are parked for a long time pools more charge points; a transit zone requires more. Only an audit can set this number for your site.

Do I need to upgrade my Enedis grid connection?

Not systematically. Dynamic load management often makes it possible to install several charge points while staying below the threshold of the existing subscription, which avoids a costly upgrade. The audit confirms the margin actually available before any decision.

AC or DC: how to choose?

It depends on parking duration. For vehicles idle for several hours, AC is usually enough and costs less. DC fast charging is justified for short turnover or public reception, where every minute counts.

How do I anticipate fleet growth?

Through pre-wiring: you deploy the heavy infrastructure from the outset so that adding charge points later happens without major works. It is almost always more economical than redoing everything with each expansion.

How much does sizing a charging infrastructure cost?

The cost depends on the number of charge points, the chosen power and the state of your grid connection: it is therefore established on a quote. At Volticom, the sizing audit and the detailed quote are free and priced within 48 hours, across France, with no commitment. You thus know exactly what your project costs before any decision.

Can I size and install my charge points myself?

An IRVE installation with several charge points involves the electrical panel, the grid connection and NF C 15-100 compliance: it requires a 30 mA Type B residual current circuit breaker and a recognised qualification. Above a certain power, installation by a QUALIFELEC IRVE-qualified electrician is mandatory, and it is also the condition for remaining eligible for the ADVENIR scheme (subject to its rules) and to eligibility. Our certified technicians handle the whole process, throughout France via our installer partners.

How long does setting up a charging infrastructure take?

The timeframe depends on the scale of the project, but installing a charge point is generally done within a timeframe confirmed after the site assessment once the study is validated and the equipment is available. Anticipated pre-wiring greatly reduces the timeframes of future expansions, since only a simple connection remains to be made. We provide you with a precise schedule as soon as the quote is delivered within 48 hours, across France.

What happens if there is a fault after installation?

All our installations are covered by a decennial liability insurance policy with AXA, subject to the declared activities, limits and terms of the current insurance certificate, with an after-sales service that intervenes. On connected charge points, OCPP monitoring makes it possible to detect and diagnose most incidents remotely, often before you even notice them. You are never left alone facing idle equipment.

Can charge point consumption be re-billed to users?

Yes: our charge points connected to the OCPP standard allow re-billing for the kWh actually consumed, ideal for a homeowners' association, a shared fleet or public reception. Combined with load shedding and dynamic power management, this function ensures a fair distribution of costs between users. We configure the re-billing solution suited to your site during the audit.

How do I obtain a sizing study for my project?

Simply contact us to schedule an on-site audit: we assess the available power, your uses and your fleet, then deliver a free, detailed quote within 48 hours, across France, with no commitment. You can reach us on 09 55 92 66 32 or at contact@volticom.fr. You thus get sizing aligned with your on-the-ground reality, neither over-sized nor cramped.

Let's size your infrastructure together

The ideal number of charge points is not a magic formula: it is the result of a precise diagnosis cross-referencing your vehicle fleet, your parking durations, your uses and the power actually available on your site. Volticom, an IRVE installer in Paris, carries out a free sizing audit to calibrate your project as precisely as possible — dynamic load management to avoid an Enedis upgrade, scalable infrastructure through pre-wiring, and support from design to follow-up, with the QUALIFELEC IRVE qualification, a decennial liability insurance policy with AXA, subject to the declared activities, limits and terms of the current insurance certificate and AXA insurance. To find out how many charge points to install at your site, request your free audit: we size on the basis of your on-the-ground reality.