EV charging station financial model: costs and utilization

An EV charging station financial model links charging activity to customer revenue, utility bills and site operating contribution. Build it by site and month, then compare the actual session export with the assumptions in your planning workbook. Keep energy sold, energy purchased and charging time separate: each answers a different operating question.

Start with the exports and the utilization definition

Bring the charging session register, utility invoice, processor settlement report and site expense ledger. Keep site ID, port ID, session dates, delivered kilowatt-hours, charging duration, billed amount, refunds and taxes in the session export. From the utility bill, take billing dates, metered consumption, energy charges, demand charges and other fees.

Count ports rather than connectors. The Department of Energy's charging station definitions distinguish a port, which serves one vehicle at a time, from its connectors. Counting every connector as separate capacity inflates the denominator.

For this workbook, time utilization means active charging hours divided by scheduled port-hours. A plugged-in vehicle that has stopped charging does not add active hours. Record occupied hours separately if parking turnover matters. Keep outages visible alongside utilization instead of quietly deleting their hours from scheduled capacity.

Use one month across every export. If the utility billing cycle differs, show the allocation method and reconcile it back to the original bill. Do not compare calendar-month sales with an unadjusted bill that covers different dates.

Build a monthly plan and actual worksheet

Put labels in column A, plan in B and actual in C. The row numbers below are spreadsheet rows; the header occupies row 1. Dollar inputs exclude sales tax, and fixed site expense includes rent, maintenance, insurance and network charges. These are illustrative assumptions for one US site in a 30-day month.

Enter these Excel formulas in column B, then copy them across to column C:

B13 = B2*B3*B4
B14 = B5/B13
B15 = B6*B7
B16 = B8*B9
B17 = B15*B12
B18 = B15-SUM(B16:B17)-B10-B11

Microsoft's formula documentation explains cell references and how relative references change when formulas are copied. Covirage is not affiliated with Microsoft.

The 40.0% actual utilization is 1,152 / 2,880. It does not directly determine energy sales: average charging power and session mix also matter. Use the recorded delivered energy for actual revenue, rather than assuming every active hour delivers the same quantity.

Explain the contribution difference

Actual revenue is $3,240.00 below plan because delivered energy is lower while the realized price is unchanged. Lower purchased energy saves $1,092.00, and lower revenue saves $97.20 in processing fees. Demand charges rise by $300.00 despite the lower monthly energy consumption.

That last movement is possible because a demand charge depends on capacity usage under the tariff, rather than simply total monthly energy. The EIA's demand charge definition describes this distinction. Use the applicable invoice calculation; do not assume a lower energy total guarantees a lower demand bill.

The proof is 4,454.00 - 3,240.00 + 1,092.00 + 97.20 - 300.00 = 2,103.20. The total contribution difference is -2,350.80, which must also equal C18-B18. Values are calculated before rounding; currency is displayed to cents and utilization to one decimal place.

This is a small variance analysis. It gives the site manager a specific question about utilization and the utility bill instead of a general instruction to cut costs.

Check the workbook before changing the plan

Reconcile charging revenue to billed sessions after refunds, then explain any timing difference to processor settlements. Settlement cash can be net of fees and taxes, so it is not automatically the revenue figure. Match the energy expense plus demand and other charges to the utility invoice.

The DOE's operation and maintenance guidance describes several charging price structures, including energy, session and time pricing. If your site uses more than one, retain separate revenue lines and calculate an effective price only after summing them.

Operating contribution here excludes installation spending, depreciation, financing and income taxes. Use a separate cash schedule for those items. A break-even analysis can test operating volume assumptions, but it should not turn this monthly comparison into a promise about recovering construction costs. A gas station financial workbook has related site economics with different throughput and inventory drivers.

Where it goes wrong

• Using billed energy as utility consumption. Purchased and delivered kilowatt-hours need their own rows and reconciliation.
• Changing the capacity denominator. Removing downtime can raise reported utilization without adding a single charging hour.
• Applying one tariff to every period. Demand charges and time-based energy prices can change the bill even when monthly throughput is stable.
• Treating contribution as cash. Equipment spending, settlement timing and loan payments affect cash outside this operating subtotal.

Compare your own charging site file in Covirage

Bring your monthly charging export, utility costs and planning workbook; Covirage maps the columns, and its tools compute and check the figures. The external AI model explains the differences with every figure traced to its rows. Create a free Covirage account and bring a sample of your own data.

See FP&A reporting with Covirage for the supporting finance workflow.