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How to calculate electric truck charging costs per kilometre
Updated: 12 minutes ago
Electric truck charging costs depend on more than the electricity price per kilowatt-hour. Charging infrastructure, demand-related charges and fleet utilisation also affect what a business pays for each kilometre travelled.
For CFOs comparing electric and diesel vehicles, those costs need to be included consistently in the financial assessment. For fleet managers, the charging system must supply enough energy to prepare vehicles for their next shift.
This article explains how to calculate charging costs per kilometre, understand the relationship between charging speed and depot demand, and assess where solar PV and battery storage can help.
What to include in electric truck charging costs
Start by distinguishing two useful measures:
Purchased-electricity cost per kilometre: electricity usage charges attributable to fleet charging, divided by the fleet’s distance travelled.
Charging-system cost per kilometre: electricity usage charges plus the other costs of providing charging, divided by the same distance.
Consider an illustrative depot with 10 electric trucks travelling a combined 40,000 km per month. Metering records 40,000 kWh supplied to their charging system, costing R80,000 in electricity usage charges.
Purchased-electricity cost = R80,000 ÷ 40,000 km = R2.00/km
Now include the other costs associated with charging:
Cost attributable to fleet charging | Illustrative monthly amount |
|---|---|
Electricity usage charges | R80,000 |
Additional demand and capacity charges | R12,000 |
Charging infrastructure finance or lease payments | R15,000 |
Charging software, support and maintenance | R5,000 |
Total charging-system cost | R112,000 |
Charging-system cost = R112,000 ÷ 40,000 km = R2.80/km
These figures are hypothetical, not Aeversa pricing or a performance forecast. The example assumes grid-only charging, separately billed items and consistent VAT treatment. Electricity is measured at the input to the charging system, so charging losses are already included.
The difference between R2.00/km and R2.80/km shows why every cost estimate needs a clear breakdown.
When comparing electric and diesel vehicle total cost of ownership, add vehicle finance, maintenance, insurance and other relevant operating costs. Include each cost once. If a charging service fee already covers infrastructure and maintenance, adding those items separately would overstate the cost.
Also distinguish additional project expenditure from existing depot costs allocated to the fleet. An allocation does not necessarily represent an increase in cash expenditure.
How charging schedules affect depot power requirements
Energy and power describe different requirements:
Energy, measured in kilowatt-hours (kWh), is the amount of electricity needed.
Power, measured in kilowatts (kW), is the rate at which that energy is delivered.
Suppose the depot’s trucks need 600 kWh delivered to their batteries before departure.
Available charging time | Required average charging output |
|---|---|
Six hours | 100 kW |
Three hours | 200 kW |
The calculation is energy divided by time. These simplified figures exclude charging losses and assume charging can be distributed across the available window. Actual design must account for individual vehicle schedules, charging limits and changes in charging power during a session.
The shorter window requires twice the average output to deliver the same energy. This matters when vehicles return late, run a second shift or need to depart together.
Charging must also share the depot’s electrical supply with refrigeration, conveyors, lighting and other equipment. The charging plan needs to account for those loads when determining how much power is available to the trucks.
How demand charges can affect electric truck charging times
Depending on the tariff, part of a depot’s electricity bill may be linked to measured maximum demand or contracted supply capacity. These charges are separate from the charge for each kilowatt-hour consumed. Their calculation depends on the electricity supplier and tariff.
Charging several trucks together can increase the depot’s grid demand. One way to manage this is to limit charging power when the site approaches a chosen grid-demand limit.
That can help control demand-related costs, but it may also increase charging time. In the example above, limiting total charging output to 100 kW would mean allowing at least six hours to deliver 600 kWh. If the fleet needs that energy within three hours, the charging plan would not meet the requirement.
The decision therefore needs to account for both the tariff consequences of drawing more power and the operational consequences of charging more slowly. A power limit is only workable if vehicles can still be ready for departure.
How solar PV and battery storage can support faster charging
On-site solar PV and battery storage can supply additional power to charging stations while limiting the amount drawn from the grid.
For example, suppose 100 kW of grid power is available for fleet charging after accounting for other depot loads. If solar PV supplies a further 60 kW and battery storage supplies 40 kW, the system could provide 200 kW for charging while drawing only 100 kW from the grid for that charging load.
This could meet the example fleet’s three-hour charging requirement if those contributions are sustained and the charging equipment and vehicles can accept the required power. The calculation is illustrative and excludes losses. Supplying 40 kW from storage for three hours would require 120 kWh of delivered energy, with additional capacity allowed for losses and operating limits.
Solar output varies, and a battery has limits on both its discharge power and available energy. A control system using software such as Ampcontrol needs to dynamically adjust charging as solar generation, battery availability and other site loads change.
When enough on-site power is available, chargers can potentially operate at full rated output without creating the equivalent increase in grid demand. When that contribution falls, charging may need to slow down to maintain the grid-demand limit.
Solar and storage do not automatically eliminate demand or capacity charges. Their value depends on the tariff, system design and whether they can supply power during the periods that affect the bill and vehicle schedule.
How to include solar and storage in charging costs
Compare the cost of providing solar and stored energy with the grid purchases and demand-related charges they are expected to reduce. Include the applicable equipment, finance, maintenance and replacement costs, together with energy losses.
Compare grid-only charging with charging supported by solar PV and battery storage using the same routes, distances and departure times. For each system, calculate the total charging cost per kilometre and check whether it can deliver the energy each truck needs before its scheduled departure.
If faster charging is expected to support additional routes or reduce delays, explain that operational benefit separately and state the assumptions behind it.
How fleet utilisation changes charging costs per kilometre
Some charging costs, such as electricity usage charges, vary with distance travelled. Fixed monthly costs, such as a charger lease payment, remain the same regardless of how many kilometres the fleet travels.
Return to the original grid-only monthly example. Suppose fleet distance falls by 25%, from 40,000 km to 30,000 km. If electricity consumption falls proportionately and the effective electricity price stays unchanged, usage charges fall from R80,000 to R60,000.
If the remaining R32,000 of monthly costs stays unchanged:
Charging-system cost = R92,000 ÷ 30,000 km = R3.07/km
Purchased-electricity cost remains R2.00/km, but charging-system cost rises from R2.80/km to approximately R3.07/km.
Lower monthly energy consumption does not necessarily mean a lower maximum demand. A smaller number of charging sessions could still create the same peak if they overlap. The assumption that demand-related costs stay unchanged must therefore be checked against the expected charging pattern and tariff.
Test lower utilisation as well as the expected operating volume, particularly for seasonal operations or a gradual vehicle rollout.
Five questions to assess your depot’s capacity for EV charging
Before selecting chargers or approving a fleet expansion, establish how the proposed charging demand will fit within the depot’s power supply:
How much power can the site supply under its existing connection? Confirm the contracted supply capacity and the limits of the site’s electrical infrastructure. These may differ, and both affect how much charging can be added.
How much of that capacity is available when trucks need to charge? Review measured site demand across the operating day, including busy periods and seasonal loads. A monthly electricity total does not show how much spare power is available during a particular charging window.
How much energy will the planned electric fleet need each day? Estimate requirements from the proposed vehicle numbers, routes, distances, payloads and duty cycles, allowing for charging losses. Include the next planned phase of fleet growth.
What charging power is needed to meet departure times? Use each vehicle’s energy requirement and available charging time to determine which charging sessions will overlap. Test late returns and shorter turnaround times to identify the periods of highest combined demand.
Can the site meet that combined demand, and at what cost? Compare the projected charging load with the depot’s existing loads and supply limits. If there is a shortfall, assess whether charging schedules, solar PV, battery storage or a supply upgrade can resolve it, including the effect on demand-related charges.
These answers provide a basis for sizing the charging system and calculating its cost. Where site-load measurements or fleet-demand estimates are missing, the proposal still relies on assumptions that could affect both vehicle readiness and project expenditure.
Assess depot power capacity before investing in EV charging
Aeversa’s Power Demand Assessment focuses on the site’s existing electrical load, available capacity and constraints, with scope and timing agreed for each depot.
Combined with vehicle energy requirements and operating schedules, those findings inform required charging capacity, potential site upgrades and the assumptions used in the financial assessment.
Bring your electricity bills, planned vehicle numbers and typical return and departure times to the initial discussion.
Written By:
 | John Henry Ford Sales Manager AEVERSA |
Author Bio:
John is the Sales Manager at Aeversa, where he specialises in fleet electrification and sustainable energy solutions. With a strong background in the EVSE and automotive industries, John has led initiatives that integrate electric vehicle charging infrastructure with renewable energy sources, such as solar power and battery storage.
His work focuses on enhancing operational efficiency and reducing costs for logistics and distribution fleets. John is passionate about advancing clean transportation technologies and has been instrumental in projects that demonstrate the practical benefits of fleet electrification in South Africa.
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