The short answer
Estimate charging energy from miles driven and vehicle consumption, add charging losses, then apply the relevant electric rate. Public charging has its own fee structure.
The decision this guide helps you make
Keep home or workplace metered energy separate from public-session pricing. A price per minute, session fee or idle fee needs its own calculation.
Evidence to gather before deciding
Gather monthly miles, vehicle kWh per 100 miles, charging efficiency assumption, all-in electric rate and any incremental fixed charges.
The detail that is easy to miss
At a business, simultaneous charging may create a demand peak. An energy-only miles calculation does not capture that demand charge or electrical upgrade cost.
Include charging losses and peak overlap
Decision case · figures, where used, are hypothetical
Delivering an illustrative 1,000 kWh to batteries at 90% efficiency requires about 1,111 grid kWh. At $0.12/kWh, energy costs about $133 before demand and equipment costs. Use measured efficiency where available.
What would make this decision ready?
Two 20-kW chargers operating together can affect the site peak differently from sequential charging. Test overlap with the building load. A calculator does not approve electrical capacity or installation.
Calculate metered electricity, not just battery energy
Multiply monthly miles by the vehicle’s kWh per 100 miles and divide by 100. Divide that result by charging efficiency as a decimal to estimate metered energy. Multiply by the applicable price per kWh. Public charging can add session, idle, parking or other charges, so a home-rate calculation should not be presented as an all-network charging budget.
Check the business demand effect
A charger adds power while it operates. Several chargers running together can coincide with the site’s existing peak. Managed charging may change when that load occurs, subject to vehicle readiness and operational constraints. Use interval data and the tariff to evaluate billed demand. The energy calculation alone does not capture demand charges, service upgrades, network fees or maintenance.
Verify current program and tax timing
Use the exact utility program and current IRS guidance before assigning an incentive to a charger project. The IRS currently states Section 30C qualifying property must be placed in service before July 1, 2026 and meet applicable requirements, including location rules. Do not assume an old credit applies to a new installation. Distinguish a tax benefit from a utility rebate and confirm eligibility with appropriate professional help.
An energy-only charging example
For illustrative monthly driving of 1,000 miles at 30 kWh per 100 miles and charging efficiency of 90%, metered energy is about 333.33 kWh. At an illustrative all-in 15 cents/kWh, energy cost is $50. This excludes incremental demand, charger hardware, installation and public fees. Shifted charging reduces this figure only if the relevant rate or cost component changes with time.
| Record | Why it matters | How to verify |
|---|---|---|
| Account and scope | Keeps the decision tied to the right service and customer. | Use the current utility, meter and customer class; keep account identifiers private. |
| Period and units | Prevents comparisons across different months or measures. | Write down billing days and whether the amount is kWh, kW, therms or dollars. |
| Written terms | Distinguishes a claim from an obligation. | Save the full proposed agreement, tariff or program notice and its date. |
| Unknowns and exclusions | Shows what the estimate cannot establish. | List unresolved charges, eligibility and operating assumptions before deciding. |
Use a tool without sending your numbers
A calculator is useful for checking an assumption, not for confirming a tariff, incentive or legal interpretation. Enter only nonidentifying figures in the relevant worksheet. If you need a human review, describe the question and utility first; do not paste an account number or confidential document into the inquiry. Keep the model alongside the written terms so an apparently precise output is not mistaken for a complete quote.
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Sources & further checks
Primary references checked for this guide on October 15, 2026. Follow the source for current tariffs, eligibility and program terms; rates here are not live offers.