EV Charging ROI and Total Cost of Ownership Modelling

Inputs that carry the result

Most charging models are dominated by three inputs, and the rest contribute noise. Utilisation, the energy margin including any demand-based component, and uptime. Getting these three approximately right matters far more than getting everything else precisely right.

Costs models routinely omit

• Demand or capacity charges, which are fixed and can exceed energy cost at low utilisation
• Connectivity per charger, small individually and material across a fleet
• Payment processing, which scales with revenue rather than energy
• The cost of an engineer physically reaching a site, which dominates rural service economics
• Revenue lost during downtime, and the lasting utilisation damage from a driver finding a broken bay
• Equipment refresh, because chargers do not last as long as the civil works around them

Model the range, not the point

For each dominant input, establish the value at which the decision changes rather than the value you expect. The useful output is not a payback figure. It is the sentence: this works provided utilisation exceeds a certain level and the tariff structure does not include a demand charge above a certain point.

That form survives contact with reality. A single payback number does not, because it was always conditional and the conditions were left implicit.

Ramp is not instantaneous

A site does not reach steady-state utilisation on day one. Models that apply mature utilisation from month one overstate early cash flow substantially, which matters most for the operators least able to absorb it.

Asset lives differ

Civil work and distribution infrastructure outlast chargers, frequently by a wide margin. A model that depreciates everything over one life either overstates the cost of the durable part or understates the refresh cost of the equipment.

What we will and will not do

We build the model structure with your inputs, and identify which assumptions carry the result. We do not publish benchmark utilisation figures or payback periods, because they vary enough by location that a published figure functions as an anchor rather than as information.

Three inputs that are usually guessed

A TCO model is only as good as the three or four inputs that dominate it, and those are usually the ones taken from a slide rather than from operation.

1. 1

   Utilisation

   Not one number. Apartments run highest and concentrate overnight, homes run lower, workplaces fill in a morning window. Model the site type you actually have.

2. 2

   Failure and service

   Unit failures across our AC fleet run near 0.5 percent, about one in two hundred, and that sizes spares. It does not size support. A large share of calls logged as charger faults are the supply, the installation or the vehicle, and they consume engineer time regardless of who owns them.

3. 3

   Supply capacity

   Modelled against simultaneous demand it becomes the largest line in the model. Modelled against scheduled demand it can shrink to nothing. Decide which assumption you are using and state it, because it moves the answer more than any other input.

How we would work through this with you

We build these models with your numbers rather than ours, and we hand them over so your finance team can pull them apart. A model you cannot audit is a slide.

Where the model does not support the project, that is the finding. We have told customers not to proceed and it is a better outcome than a deployment that underperforms for six years with our name on it.