Electrifying a company fleet: choosing wallboxes for businesses

Why a wallbox in a fleet is more than just a socket

A single wall-mounted charging station for a private home can still be chosen with common sense. In a fleet, whether a trades business with three vans, a care service with ten vehicles, or a logistics depot with several dozen, the criteria shift fundamentally. Suddenly it is no longer about a single device but about a charging infrastructure that has to supply several vehicles simultaneously, avoid overloading the service connection, bill electricity correctly and, if required, communicate with the energy supplier. From the second charging point onwards, a purchase turns into an infrastructure project.

In addition: commercial wallboxes are typically depreciated over several years and are expected to grow later. Anyone installing three charging points today and intending to operate twelve in two years should choose the system, load management and backend so that this scaling remains possible without civil engineering or transformer replacement. Topics such as calibration law, access management, dynamic electricity tariffs or the later connection of an in-house PV system also move into the foreground, all aspects that hardly play a role in the home carport.

AC or DC, which charging power suits the fleet?

The fundamental question is: alternating current (AC) or direct current (DC)? An AC wallbox with 11 or 22 kW always makes sense in a fleet when the vehicles are stationary for several hours, for example overnight in the depot or during working hours in the employee car park. The on-board chargers in most current electric cars and vans accept 11 or 22 kW AC, so a 22 kW wallbox overnight is generally enough for the next working day. For pure depot charging, AC is the economically sensible answer.

DC pillars charge faster, typically in the 50 to 150 kW range and above. They are worthwhile above all when dwell times are short, for example in multi-shift logistics, fast charging between two appointments, or in a passenger car fleet that commutes during the day. However, DC pillars are significantly more expensive to purchase, require a stronger grid connection, dedicated foundations and more complex ventilation, they are more of a rapid charging pillar than a wall-mounted charging station. As a rough guide: pure depot charging overnight almost always works with AC. As soon as vehicles need to be fully charged again within a few hours and are not regularly parked overnight, DC comes into play. For mixed fleets, a combination has proven itself in practice, AC for the base load and depot vehicles, DC for the critical vehicles.

A helpful question when deciding: how many kilometres does the vehicle need per day? If the daily energy requirement can also be recharged overnight on a 22 kW AC wallbox, DC is unnecessary. If not, DC becomes relevant. Companies that are growing should also ensure that the chosen manufacturer offers both AC wallboxes and DC pillars within one ecosystem, this simplifies backend and maintenance.

Load management, mandatory with multiple charging points

As soon as more than one wallbox can charge at the same time, a problem looms: if all points are driven at full power, this quickly exceeds the business's service connection. This is precisely where load management (English load management) comes in. It distributes the available connection capacity dynamically across the active charging points, first come, first charged; those who plug in only in the evening are topped up afterwards. This way, the same connection capacity can be used for significantly more vehicles without having to ask the grid operator to extend the transformer.

Legally, the topic is embedded in § 14a EnWG: the Federal Network Agency regulates the grid-friendly control of controllable consumption devices such as wallboxes. Anyone using funding from the Federal Charging Infrastructure Funding programme generally has to demonstrate that the system can be operated in a grid-friendly manner, functioning load management is effectively a prerequisite here. In addition, many distribution grid operators require every wallbox above 11 kW to be registered in any case.

Looking at the market, it becomes clear: inexpensive consumer wallboxes often come with no load management or only static load management. In a fleet, the system should therefore at least support static load management, preferably dynamic load management, which evaluates free capacity at the service connection in real time. Those who want to go a step further include PV generation and a stationary battery in the control loop, this way the fleet preferentially runs on solar power and protects the grid connection.

Calibration-law-compliant billing and access management

When employees, customers or guests charge their private cars on company parking spaces, the matter becomes relevant for accounting and legal purposes. In Germany, the Measurement and Calibration Act (MessEG in conjunction with MessEV) applies: anyone selling or passing on electricity to third parties needs calibration-law-compliant billing. In practice this means calibrated meters, transparent tariffs and a backend that documents charging processes tamper-proof, every kilowatt hour must be attributable to a specific user.

Many modern wallboxes therefore rely on the so-called calibration-law solution with signatures and transaction transmission via the open OCPP protocol (Open Charge Point Protocol). This allows each charging process to be assigned to a user in a tamper-proof manner and a billable invoice to be generated at the end, a prerequisite both for payroll when employees charge and for invoicing hotel guests, logistics customers or retail visitors.

Equally important is access management. RFID cards, key fobs or smartphone connection via app regulate who is allowed to charge at all. In a corporate environment, a solution is recommended that can be integrated into existing employee directories, shift systems or hotel PMS, so that nobody loses a key and nobody has to keep running a makeshift solution in the long term. Those who look out for an open interface (e.g. OCPP 1.6 or higher) can later switch the backend without having to replace the wallbox.

Grid connection and connection capacity at the business

The wallbox does not float in a vacuum, it is connected to the business's grid connection. Its free capacity is often the limiting factor for the entire electrification. A 22 kW AC wallbox draws around 32 A per phase; several of these operating simultaneously require connection capacities that a medium-sized business frequently does not have readily available. This is another reason why load management is so important.

In practice, the responsible grid operator checks when the wallbox is registered whether the connection point is sufficient. Adjustments to the grid connection, larger fuses, a dedicated transformer station, medium-voltage connection, cost time and money, but are often unavoidable if a larger fleet is to be converted to electric. This lead time is frequently underestimated in fleet planning and helps determine the timing of the switch to electric mobility.

Anyone wanting to keep the connection capacity small should factor in load management, PV self-consumption and, where possible, a stationary battery from the outset. An early consultation with the local energy supplier and a certified electrical specialist is therefore part of any serious fleet planning, ideally before the first vehicle is ordered.

Funding and tax, the economic side

Two factors play a central role in the economics of a fleet wallbox: subsidies on the one hand and tax treatment on the other. For commercial charging infrastructure, there is the Federal Charging Infrastructure Funding programme at federal level, which supports companies and fleet operators in particular in setting up non-publicly accessible charging points. In addition, KfW offers, within various programmes, low-interest loans and grants for companies that are converting their mobility to electric, from the wallbox through to a charging pillar network.

On the tax side, the legislator has expressly favoured charging electric vehicles at the employer's premises: under § 3 No. 46 of the Income Tax Act (EStG), the free or subsidised charging of a company electric vehicle or a private vehicle of an employee at the employer is tax-free, provided the electricity is generated or procured at the employer and supplied at a company charging station (see Gesetze im Internet). This makes employee charging attractive for both sides and the fleet effect extends beyond pure fleet electrification.

In addition, the THG quota for the electric cars registered in the fleet can generate additional revenue, further improving the economics of the charging infrastructure. However, the exact conditions of funding programmes change regularly, a current enquiry with KfW, the responsible district government office or a specialist energy consultant is mandatory before any investment.

Installation, maintenance and scalability

A commercial charging infrastructure is an infrastructure project with civil engineering, foundations, cable trays and grid connection, not an electrical goods purchase. When selecting, the following points belong on every shopping list: open communication protocols (OCPP 1.6 or higher), a manufacturer-independent backend, a modular design so that charging points can be added without civil engineering, load management with dynamic reservation of connection capacity, calibration-law-compliant meters and signatures, and a service and maintenance contract with clear response times.

Future topics are phase re-injection (charging infrastructure with unbalanced load) and preparation for bidirectional charging, which is likely to become market-ready in the coming years. Anyone planning only AC wallboxes today should at least keep the option open to retrofit DC pillars later, for example in a depot for the rapid-charge fleet. Anyone opting directly for a closed ecosystem of a single manufacturer saves on purchase costs, but pays when changing later on.

Selection checklist in three steps

1. Clarify requirements: How many vehicles are to be charged in the medium term, what dwell times do they have, what is the vehicle mix, and who is allowed to charge, just the fleet, also employees' private cars or guests?
2. Define the technology: AC or DC or a mixed operation, static or dynamic load management, calibration-law-compliant billing, open standards (OCPP) and suitable access management (RFID, app, backend connection).
3. Calculate the economics: Factor in possible funding (Federal Charging Infrastructure Funding, KfW), check § 3 No. 46 EStG for tax-free employee charging, include grid connection upgrades and maintenance costs, only then decide.