Start with energy, not chargers
Take 20 cars that each drive 60 km a day. An electric car typically uses between 0.15 and 0.20 kWh per kilometre, so we use 0.17. Each car then needs about 10.2 kWh a day. Charging is not perfectly efficient, so with 90% efficiency the depot draws about 227 kWh from the supply each night.
Then ask how fast, and how many
If the cars have ten hours to charge, the average load is about 22.7 kW. A standard 7 kW AC point can deliver 70 kWh in ten hours, so in energy terms about four points would be enough if cars were moved between them during the night. In practice most fleets install one point per car, because nobody wants to move cars at 2 a.m. That is 20 points.
Twenty 7 kW points running at once would draw 140 kW. Smart scheduling can hold the peak well below that. Our planning rule of thumb is about two and a half times the average load, which here is roughly 60 kW. The real figure comes from a site survey and the supply authority.
Solar
If you want solar to supply 40% of the energy, that is about 91 kWh a day. At around 4.5 peak sun hours, that needs roughly 20 kWp of panels. Because cars charge at night, solar helps most when paired with battery storage or when cars charge during the day.
What it costs to run
At a placeholder electricity cost of ₦225 per kWh, an electric kilometre costs about ₦43. A petrol car doing 10 km per litre at ₦1,355 a litre costs about ₦136 per kilometre. Over 22 days, 20 cars cover 26,400 km, giving about ₦1.12 million in electricity against about ₦3.58 million in petrol. The saving is about ₦2.46 million a month before the cost of the vehicles and charging equipment.
The electricity figure is a placeholder, not a quoted tariff. If your power comes from a generator, your cost per kWh will be higher, and the saving smaller. Put your own number in the depot calculator.
What the arithmetic leaves out
- The purchase or lease cost of the vehicles and the chargers.
- Demand and standing charges on the electricity bill.
- Maintenance, which is usually lower for electric vehicles but not zero.
- Heat and battery ageing, which reduce usable range.
Sources and notes
- Figures are produced by the VoltAfrica depot sizing calculator at the default assumptions: 20 vehicles, 60 km per day, 0.17 kWh per km, 90% charging efficiency, 10 charging hours, 7 kW points, 40% solar share, 4.5 peak sun hours, ₦225 per kWh, 10 km per litre, ₦1,355 per litre, 22 days per month.
- The electricity tariff is a placeholder. Petrol price is the Lagos pump price quoted for October 2026.
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