Low Utilization and High Installation Costs: Can Mobile EV Charger Solutions Improve Parking Lot ROI

A data-driven guide for parking operators, commercial property owners, fleet facilities and EV infrastructure planners

Electric vehicle adoption is expanding faster than many parking facilities were originally designed to accommodate. Yet for parking operators, installing more chargers does not automatically produce a better business case. A project can have strong EV traffic and still generate a weak return if expensive charging hardware sits idle, if electrical upgrades are oversized for short demand peaks, or if charging spaces are located where drivers do not actually need them.

That is why the next stage of EV infrastructure planning is increasingly about utilization rather than charger count. The key question is no longer simply, “How many charging points should we install?” It is “How much useful energy can each charging asset deliver, how many vehicles can it serve, and what fixed infrastructure must be built to support it?”

For facilities with variable or spatially distributed charging demand, a Mobile EV Charger can change that equation. Instead of reserving charging capability for a single fixed bay, mobile energy storage can be dispatched to the vehicle. Door Energy develops integrated storage-and-charging products for applications ranging from autonomous parking-facility charging to roadside rescue, commercial fleets, heavy vehicles and outdoor industrial power support. Explore Door Energy.

I. Parking Lot Charging Economics Are Becoming a Utilization Problem

EV charging demand is growing, but charger count alone does not measure financial performance

The long-term demand signal is clear. The International Energy Agency reported that nearly 1.8 million public charging points were added globally during 2025, bringing the worldwide total to more than 7 million. Fast and ultra-fast charging points rose from about 1.5 million in 2024 to 2.2 million in 2025. Europe also continued to expand its public network, while the United States recorded strong public charging growth.

However, network expansion and individual-site profitability are different questions. IEA estimates that time-based utilization of the European public charging network was about 10% in 2025 and is expected to rise to about 15% by 2035. In other words, demand is increasing, yet significant charging capacity may still remain unused during much of the day. For parking operators, this distinction matters because capital expenditure is paid upfront while revenue is earned only when energy is actually delivered.

Data note: IEA, Global EV Outlook 2026. Values are network-level indicators and are not a forecast for any individual parking site.

Source: IEA Global EV Outlook 2026

Parking behavior creates a mismatch between where cars stay and where charging equipment is installed

Parking facilities have an unusual operating profile. A workplace garage may experience a sharp arrival wave in the morning and very little new demand after lunch. A hotel may have long vehicle dwell times but a concentrated evening charging peak. A shopping center may experience high turnover and unpredictable parking-space selection. Airport parking can involve extremely long dwell times, even though the actual energy-delivery requirement for a vehicle may be modest relative to the total time it occupies a bay.

This creates a utilization problem at two levels. First, the charger itself may be idle. Second, even when a vehicle remains parked for many hours, the connector may only be actively transferring energy for a fraction of that time. U.S. Department of Energy analysis of about 2.4 million DC fast-charging sessions from 2020 to 2023 found that paid sessions averaged 42 minutes and 22 kWh. The operational implication is straightforward: long parking duration does not necessarily require one charger to remain tied to one vehicle for the entire stay.

Operational patterns vary by site; a site-specific dwell-time and charging-demand study should be completed before investment.

II. Why Fixed Charging Can Produce High CAPEX and Low Asset Utilization

The charger is only one part of the installed cost

Fixed EV charging is often budgeted too narrowly. The hardware price is visible, but civil works and electrical infrastructure can be equally important. Depending on the site, the project may require trenching, conduit, switchgear, protection devices, transformer upgrades, utility coordination, engineering drawings, permits, inspections, network commissioning, signage and accessibility work. Long cable runs across a parking garage can also make installation progressively more expensive as chargers are distributed across additional bays.

The U.S. Department of Energy Alternative Fuels Data Center currently cites public charger hardware costs of approximately USD 3,500 per connector for Level 2 and roughly USD 38,000-90,000 per connector for DC fast charging, with higher DCFC costs depending on power output. DOE also emphasizes that installation cost varies materially with trenching, existing wiring, required electrical upgrades, labor and permitting.

Source framework: U.S. DOE AFDC charging-infrastructure development and O&M guidance.

Low utilization makes every fixed dollar more expensive per delivered kWh

A useful way to think about charging economics is to divide fixed annualized cost by actual energy throughput. If two charging assets have the same annual ownership cost but one delivers four times more energy, its fixed cost per delivered kWh is one-quarter as high. This is why utilization is not just an operational KPI; it is a direct cost-allocation mechanism.

A U.S. public-charging study covering 3,705 public stations and 8,732 ports found that, in March 2022, public Level 2 charging averaged 5.6 kWh per port per day and 0.42 sessions per port per day, while public DC fast charging averaged 13.5 kWh per port per day and 0.69 sessions per port per day. These are historical observations rather than a 2026 market average, but they illustrate the economics of early-stage infrastructure: a charger can exist, be functional and still deliver relatively little energy.

Historical benchmark from a U.S. public-charging study using data through March 2022. It should not be treated as a current utilization estimate for every market or site.

Source: Public Electric Vehicle Charging Station Utilization in the United States (OSTI/NREL-associated research)

Demand charges and grid peaks can penalize low-use high-power infrastructure

High-power charging can also increase electricity cost through demand-based tariffs. DOE guidance notes that DC fast charging is more likely to trigger demand charges than Level 1 or Level 2 charging. NREL research similarly shows that demand charges can have a particularly large effect on low-utilization DC fast-charging sites because the site may pay for a high monthly peak even when total monthly energy sales are modest.

This creates a classic parking-lot problem: electrical infrastructure must be capable of supporting the peak, while the business earns money from average utilization. If several vehicles request high-power charging at the same time for only a short window, the grid connection and transformer may be sized for a condition that exists for a small fraction of the day.

Sources: DOE AFDC - O&M and demand charges | NREL REopt DCFC case study

Grid connection timelines can also become an investment risk

Capital cost is not the only risk. U.S. DOE research on EV charging soft costs notes that DC fast-charging projects can take from six months to more than two years to energize, depending on requested capacity, grid upgrades, equipment availability, permitting, easements and local processes. A parking operator therefore has to consider not only “What will the charger cost?” but also “How long before the asset can begin generating revenue?”

Source: U.S. DOE - Understanding the Soft Costs of EV Charging

III. How a Mobile EV Charger Changes the Parking Lot Cost Structure

The core change is from fixed-bay capacity to shared, dispatchable capacity

In a traditional model, charging capacity is geographically fixed. A vehicle must move to an equipped bay, and the charger can only serve vehicles that reach that location. A Mobile EV Charger reverses the service logic: the vehicle can remain in a standard parking position while the energy asset moves within an approved operating area. That mobility allows one storage-and-charging unit to serve multiple bays over time.

The economic value comes from sharing. A parking operator does not necessarily need high-power electrical infrastructure at every location where a future charging request might occur. Instead, the operator can build a smaller number of fixed base chargers, establish one or more replenishment points for mobile units, and dispatch mobile capacity when fixed infrastructure is occupied or demand appears in another zone.

This matrix is a planning guide, not a project-specific financial recommendation.

Mobile storage can separate the timing of grid consumption from vehicle charging

Energy storage introduces another dimension. The unit can be replenished when facility load is lower and then deliver energy to vehicles during a higher-demand period. This does not eliminate the need for grid energy; instead, it creates a buffer between when electricity is drawn from the site and when it is delivered to vehicles. NREL research has found that behind-the-meter storage can be effective for peak shaving and is particularly useful for peaky or low-utilization DC fast-charging loads under demand-based tariffs.

For parking facilities, this can be valuable when the transformer has adequate energy capacity over the day but insufficient instantaneous capacity to support several high-power chargers at the same moment. A well-designed mobile storage strategy can therefore postpone some infrastructure expansion, reduce peak coincidence, or improve service before a permanent grid upgrade is justified. The exact savings depend on local tariffs, operating schedules, charging power and storage cycling.

Source: NREL REopt - PV and Storage for DC Fast Charging

Managed charging already shows why parking dwell time is an energy-management opportunity

A U.S. Department of Energy case study of a national-laboratory parking garage illustrates the broader principle. The facility had 108 EVSE parking spaces and a potential 720 kW peak load. Because an eight-hour workday creates significant vehicle dwell time, managed charging was used to limit peak power rather than simply upgrading transformers to accommodate the theoretical simultaneous maximum. Mobile charging applies a related logic in physical space: if vehicles remain parked long enough, energy can be sequenced rather than delivered to every vehicle at once.

Source: DOE - Managed Charging in a Parking Garage

What mobility does not solve

A mobile system is not automatically cheaper. It adds batteries, drive systems, controls, navigation hardware, dispatch software and operating procedures. It also needs a safe replenishment point, suitable routes, collision-risk controls and maintenance planning. If a site already has inexpensive electrical capacity, high utilization at fixed bays and continuous charging demand, a fixed charger may produce the lower total cost of ownership. The business case must therefore compare the avoided fixed infrastructure and improved utilization against the additional cost of mobility and storage.

IV. Door Energy MCP-D: Autonomous Mobile Charging for Parking Facilities

A parking-specific Door Energy platform, separate from the 420 kW rescue and industrial system

Door Energy develops several storage-and-charging platforms for different use cases. For parking facilities, the most relevant product is the MCP-D autonomous charging unit. The published product specification lists 105 kWh battery capacity, up to 100 kW EV charging output, CCS1/CCS2 interfaces, a 200-1000 VDC output range, OCPP 1.6J communication, IP55 protection, liquid cooling, L4 autonomous capability and a maximum travel speed of 10 km/h.

Door Energy positions the MCP-D as a Mobile EV Charger for controlled parking environments where charging demand shifts between bays. View the 100 kW Autonomous Mobile EV Charger or review the MCP-D parking-facility solution case.

Product data source: Door Energy MCP-D product page. Site conditions, operating procedures and final configuration should be confirmed for each project.

Five-step charging workflow: from request to task completion

The practical advantage of autonomy is that charging can become an on-demand parking service instead of a fixed-space amenity. The workflow can be integrated into a parking platform, facility-management system or fleet-dispatch environment. Door Energy describes a five-step process:

Workflow adapted from Door Energy parking-facility application information.

The ROI KPI should shift from “chargers installed” to “charging tasks completed”

Once charging is dispatchable, the operator can manage the system as a service fleet. Relevant KPIs include charging tasks per unit per day, delivered kWh per operating hour, travel time per task, queue time, percentage of tasks completed before customer departure, energy remaining before replenishment, replenishment downtime, uptime and cost per delivered kWh. These metrics make it easier to determine whether one additional mobile unit creates more value than several additional fixed bays.

Door Energy also supports higher-power rescue and industrial applications

The parking-focused MCP-D should not be confused with Door Energy’s larger high-power mobile storage products. Door Energy also manufactures a 420 kWh mobile energy storage and charging system with up to 420 kW total EV charging output across four charging guns, OCPP 1.6J communication and CCS1/CCS2 interfaces. This larger platform is intended for applications such as road rescue, heavy vehicles, construction machinery, temporary industrial power and other locations where high-power energy must be brought to the load.

For these broader applications, see the Door Energy Mobile EV Charger product range, the 420 kWh mobile storage-and-charging system, and Door Energy’s application solutions. The larger system can also supply AC loads for equipment such as electric excavators, pumps and temporary lighting, depending on configuration.

Door Energy uses a modular product architecture to simplify service and component replacement. For operators, modularity matters because maintenance cost is not limited to the price of spare parts; it also includes downtime, technician time and the revenue lost while a charging asset is unavailable. A system that can be diagnosed and serviced at module level can therefore improve lifecycle economics, particularly in commercial duty cycles.

V. Building a Realistic ROI Model: Fixed, Mobile or Hybrid?

Start with energy throughput, not nameplate power

The simplest way to understand utilization is to convert rated charging power into annual energy throughput. A 100 kW charger operating at full rated power every hour of the year would theoretically deliver 876,000 kWh. Real assets never operate this way, but the number provides a denominator for scenario analysis. At a 5% equivalent power utilization rate, annual throughput would be 43,800 kWh; at 20%, it would be 175,200 kWh.

The following example uses a hypothetical USD 0.20 contribution margin per delivered kWh after variable electricity cost. It is not a Door Energy revenue claim and does not represent any specific market tariff. Its purpose is to demonstrate how utilization can dominate asset economics.

Illustrative scenario only. Actual revenue and margin depend on tariff structure, charging price, losses, maintenance, labor, software, battery depreciation and local taxes.

A better ROI formula includes both avoided infrastructure and mobile operating cost

For a fixed-charging project, the investment model should include equipment, installation, utility upgrades, civil works, engineering, permits, networking, maintenance and energy costs. For a Mobile EV Charger, the model should include equipment acquisition, storage degradation, replenishment losses, maintenance, navigation/dispatch systems, labor where manual connection is used, insurance and site adaptation. The correct comparison is therefore total cost of service, not hardware price.

Illustrative 200-space parking-lot scenario

Consider a 200-space commercial parking facility where EV demand is growing but still uneven. The operator expects 20-30 charging requests on a busy day, but those vehicles park across multiple zones. A fixed-only design might create 20 dedicated charging spaces and size electrical infrastructure for substantial simultaneous load. A mobile-only design could reduce fixed bay count but would require enough stored energy and mobile task capacity to meet service-level targets. A hybrid design could install a smaller fixed base and use one or more mobile units for overflow and dispersed requests.

Conceptual scenario only. A project model should use measured parking dwell time, arrival distribution, SOC, charging acceptance and local tariff data.

When a Mobile EV Charger is most likely to improve investment return

The strongest cases are usually sites where flexibility has measurable financial value. Examples include properties where the next fixed charging expansion would trigger a transformer upgrade, where demand moves between parking zones, where utilization is still too low to justify one charger per planned EV bay, or where the property owner expects the EV share to grow rapidly but does not know the final charging mix. Mobile storage can also be valuable when a facility wants to launch a charging service before a larger grid connection is available.

• Charging demand is growing, but the exact number and location of future charging sessions are uncertain.
• The site has long vehicle dwell times, allowing charging to be sequenced rather than simultaneous.
• High-power electrical infrastructure at every target bay would be expensive or disruptive to install.
• Short peak periods create a high maximum demand relative to average daily energy use.
• Parking-space flexibility is commercially valuable, so permanently reserving many EV-only bays has an opportunity cost.
• The operator can integrate task scheduling, payment, fleet or parking data to dispatch charging intelligently.

When fixed charging is still the better investment

A high-throughput charging hub with constant demand, inexpensive grid capacity and predictable vehicle flows may not benefit much from mobility. If a fixed 150 kW or 350 kW charger can remain busy for much of the day, then the civil and electrical investment is being spread across substantial throughput. Likewise, a fleet depot with highly repeatable parking positions may prefer pantographs, fixed dispensers or high-power cable management rather than moving an energy-storage robot between vehicles.

The correct conclusion is therefore conditional: mobile charging improves ROI when it reduces expensive idle capacity, delays infrastructure that would otherwise be underused, or allows one asset to complete substantially more economically valuable tasks. It does not create value simply because it moves.

A practical decision scorecard for parking operators

Qualitative scorecard based on the economic logic discussed in this article; not a substitute for engineering and financial modeling.

VI. FAQ: Mobile EV Charger ROI for Parking Facilities

Can a Mobile EV Charger reduce parking-lot charging infrastructure costs?

It can reduce or defer some fixed infrastructure when charging demand is dispersed or still uncertain. The largest potential savings usually come from avoiding premature installation of high-power equipment at many bays, reducing long cable routes, or delaying a transformer and distribution upgrade. However, mobile systems have their own acquisition and operating costs, so the savings must be demonstrated with a site-specific total-cost model.

Is a Mobile EV Charger always cheaper than installing fixed chargers?

No. If fixed chargers can achieve high daily utilization and the site already has adequate electrical capacity, a fixed installation may have the lowest cost per delivered kWh. Mobile charging is most attractive when flexibility, storage and shared use create measurable value that fixed hardware cannot provide economically.

How does Door Energy’s autonomous charging process work in a parking facility?

A charging request is submitted through a platform or dispatch system. The vehicle location is identified using mapped parking information and available sensors. The MCP-D then travels to the target vehicle, the connection is completed automatically in a robotic-arm configuration or manually by trained staff, and the charging session begins. After the target condition is reached, the unit can proceed to another task, return to standby or recharge.

What are the key specifications of the Door Energy MCP-D?

Door Energy publishes a 105 kWh battery capacity and up to 100 kW EV charging output for the MCP-D, with CCS1/CCS2, OCPP 1.6J, 200-1000 VDC, IP55 protection, liquid cooling, L4 autonomous capability and a maximum travel speed of 10 km/h. Gradeability is listed at more than 20%, which is relevant to many parking-garage ramps. Final project configuration should always be confirmed against the actual site.

Can the 100 kW Door Energy product provide bidirectional charging?

The product page lists up to 100 kW EV charging power and separately describes a 50 kW two-way charge/discharge function in its feature information. Because bidirectional capability may depend on configuration and system architecture, project documentation should state the configured bidirectional power separately rather than assuming that all 100 kW charging power is bidirectional.

Can mobile charging reduce grid-upgrade requirements?

In some projects, yes. Storage can allow the facility to replenish energy at lower-load periods and deliver it later to vehicles, while mobile dispatch can reduce the need to install high-power feeds at every service location. This may defer an upgrade, but it does not eliminate the need for adequate daily energy supply. Engineering analysis should compare transformer capacity, load profile, replenishment power and peak charging demand.

Can a Mobile EV Charger help with demand charges?

Potentially. NREL research shows that storage can be effective for peak shaving at DC fast-charging sites, particularly when loads are peaky or utilization is low. Savings depend on the local utility tariff. The operator should model demand-charge intervals, site base load, charging peaks, storage power and replenishment schedule before assuming a financial benefit.

Is the Door Energy MCP-D suitable for underground parking garages?

It is designed for controlled parking environments, and Door Energy lists L4 low-speed autonomous movement, a 10 km/h maximum speed and more than 20% gradeability. Nevertheless, every underground facility is different. Ramp slope, turning radius, lane width, pedestrian traffic, communication coverage, fire code, ventilation, emergency routes and the charging/replenishment point all require site assessment.

How many vehicles can one mobile unit serve per day?

There is no universal number. Daily task capacity depends on energy requested per vehicle, travel distance, connector time, charging power accepted by each EV, replenishment time and operating hours. A parking operator should model the system as a queue: requests per hour, average kWh per request, service time, travel time and required service level. The goal is to maximize completed economically valuable tasks, not simply the theoretical number of sessions.

How should parking operators compare fixed, mobile and hybrid designs?

Use the same financial boundary for all options. Include hardware, electrical distribution, utility upgrades, civil works, permits, networking, energy, maintenance, labor, software, downtime and residual value. Then compare annual delivered kWh, completed sessions, peak grid demand, cost per delivered kWh, revenue per asset and payback. For many commercial sites, a hybrid architecture is the most practical because it combines efficient fixed base capacity with flexible mobile peak capacity.

What other applications does Door Energy support beyond parking lots?

Door Energy develops mobile storage and charging products for road rescue, commercial vehicles, heavy trucks, construction and industrial equipment, and temporary off-grid or emergency power scenarios. The larger Door Energy mobile platform can reach up to 420 kW total DC charging output in its published configuration and can also support AC power loads such as electric construction equipment, pumps and lighting.

How quickly can Door Energy mobile storage products be replenished?

Replenishment time depends on the specific model, battery capacity, starting SOC, input power, temperature and charging curve. In appropriately matched Door Energy application configurations, DC replenishment may be designed around roughly one hour and suitable AC replenishment around roughly two hours. These figures should be treated as configuration-dependent planning references rather than universal guaranteed times.

VII. Conclusion: The Best ROI Comes from Matching Charging Architecture to Real Demand

Parking operators should resist a simple “more chargers equals better service” approach. The more useful objective is to maximize reliable energy delivery and customer coverage per dollar of installed infrastructure. Public charging networks are expanding rapidly, but the IEA utilization data and historical U.S. utilization studies both show why installed capacity can remain underused. Meanwhile, high-power fixed charging can involve substantial hardware, electrical, civil and soft costs, particularly when grid upgrades are required.

A Mobile EV Charger can improve this equation when it converts idle fixed capacity into shared, dispatchable capacity. The benefit is strongest where vehicles have long dwell times, demand is uneven, parking positions are dispersed, grid peaks are expensive or future EV penetration is uncertain. In these environments, mobile storage can be used as a flexible capacity layer rather than forcing the operator to build the final-state charging network on day one.

Door Energy’s MCP-D is specifically designed around that parking-facility logic. By integrating 105 kWh energy storage, up to 100 kW EV charging, CCS1/CCS2, OCPP 1.6J and autonomous low-speed movement, the platform allows a facility to schedule energy delivery as a task. Door Energy’s broader product portfolio then extends the same mobile-energy concept to higher-power rescue, heavy-vehicle and industrial scenarios, including a published 420 kWh / 420 kW multi-gun system.

For many properties, the strongest investment strategy will be hybrid. Fixed chargers should serve stable base demand where utilization can be high. Mobile charging can handle peak periods, overflow, hard-to-wire parking zones and demand that has not yet become predictable enough to justify permanent infrastructure. As utilization increases, the operator can add fixed capacity selectively rather than speculatively.

Before procurement, the site owner should therefore model charging demand by hour, parking dwell time, vehicle SOC, requested kWh, departure deadlines, transformer headroom, local electricity tariffs and expected EV growth. The final decision should be based on cost per delivered kWh, completed charging tasks, peak-demand exposure and total lifecycle cost—not on charger count alone.

Learn more from Door Energy: Official Website | Mobile EV Charger Products | 100 kW Autonomous Charging Robot | Parking Facility Solution | Application Solutions | Contact Door Energy