InsightsPractice
PracticeP003Energy & Fleet OperationsBy Fabrice Macarty · Maxime Ferrand

The Net Return on a Fleet Battery

V2G tariffs are on sale, and the revenue quoted to a fleet is gross: before conversion losses, before the aggregator’s retained share, before battery wear. Four contract clauses, from net ledger to downside case, turn a fleet battery into a number a CFO can approve.

$9,741/yr
upper bound of PJM Regulation revenue for a 33 kW fleet vehicle, from measured pilot performance and 2021 to 2025 market prices. The report states the figure net of energy losses and before aggregator fees, customer support and any allowance for battery wear. (UD / Exelon, final report, March 2026)
€132/MWh
compensation a vehicle owner needs per MWh of V2G energy flow to break even on battery degradation and infrastructure cost under the 2030 market scenario. BMW/E.ON’s published feed-in rate of €0.40/kWh equals €400/MWh, three times that floor, before charging cost and losses. (Sagaria et al., Applied Energy, 2025; BMW Group, February 2026)
Finance & RiskAutomotive & MobilityEnergy, Utilities & Grid
The decision stakes

From quoted revenue
to retained value.

Something that might not be obvious to everyone is that these payments are not a subsidy; these EVs are earning money by competing with legacy generators, which is novel in a lot of ways.Prof. Willett Kempton, University of Delaware, April 16, 2026

The net return on a fleet battery is what remains of the market payment once conversion losses, the aggregator’s retained share, the electricity bought to refill the pack and a provision for wear have been deducted. Only the first of those four deductions is set by physics; the contract sets the other three.

Because the same meter feeds the sustainability report and the P&L, a fleet modelling net return before signature reports its V2G contribution as metered energy returned to the grid, auditable by an external party, rather than as a narrative. Rigorous modelling makes the contribution auditable, and a board approves an auditable contribution as an asset decision.

The decision tool

Four clauses
before signature.

01

Net Ledger

Identify the contract model, direct utility or aggregator, and obtain each price in writing: the payment per hour of availability, the payment per kWh discharged and, for an aggregator, the share of market revenue retained and the fees passed through. Apply a 90% round-trip efficiency as the planning assumption, the value the Delaware pilot measured, and hold 80% as the stress floor because metered annual losses reached 16 to 25% with standby. Present the CFO with the net figure only.

The margin between what the market pays and what the fleet receives is public in a direct utility tariff and private in most aggregator contracts. Unless the agreement discloses it, that margin is modelled at the fleet’s expense, and the headline figure has been set by the party keeping the margin.
02

Soc Covenant

Write the state-of-charge window into the agreement, aligned with the OEM recommendation for the vehicle model rather than with the aggregator’s default. Calendar ageing at high charge accounts for 85 to 90% of ten-year degradation without V2G; managed cycling adds about 0.31% a year, and the Delaware vehicles, held mostly between 29 and 43%, showed no measurable loss of health after a year of service. Renault Mobilize reports unchanged warranty terms, eight years or 160,000 km, at 20 to 80%.

An OEM warranty department can verify a window written into the contract, while a window left to the dispatch algorithm gives it grounds to contest a claim. The covenant costs nothing at signature and decides who carries the battery risk for the following eight years.
03

Throughput Envelope

Specify a megawatt-hour throughput envelope in the EV procurement RFP and in the V2G service agreement: a guaranteed minimum, so the fleet is paid for a defined service, and a contractual maximum, so annual cycling stays within warranty tolerance. In a year of Regulation, the Delaware pilot moved three to five times the vehicles’ driving energy through the packs, so throughput and its effect on residual value belong in the contract as measured quantities. The OEM prices the maximum, because it carries the warranty.

A fleet requiring the envelope in its RFP obliges its suppliers to produce it, and a clause repeated across several procurement rounds becomes a market standard. Availability bonuses per hour are now published by at least one OEM; the throughput ceiling is the next figure to demand in writing.
04

Downside Case

Run the downside before the base case: Regulation prices at the low year of the series, $21 rather than $55 per MW-hour, availability cut by eight driving hours a day, the aggregator’s share at the top of its range, efficiency at the 80% floor and wear provisioned at €132/MWh of energy flow. At what net return per vehicle does the programme still cover its cost of capital? It is signable when that number stays positive in the downside, since a figure positive only in the brochure remains a forecast.

The downside number is the one a CFO can approve on the balance sheet rather than in the fleet operations budget. It also fixes the rank of the service: V2G stays secondary to mobility, and any clause allowing the grid to override a scheduled trip is priced as a cost, however small the probability.
The proof

BMW / E.ON

Germany’s first commercial V2G tariff, on sale since 9 February 2026. A private-customer product, and so far the most complete public price list available for benchmarking.

€720/yr

Availability bonus: 24 cents per connected hour with V2G active, capped at €60 a month, paid regardless of energy flow. A second, cumulative stream pays 40 cents per kWh discharged to the grid. BMW’s own footnote prices the bonus against 2,184 kWh of charging at 32.97 cents, or 12,000 to 14,000 km a year. (BMW Group press release, 9 February 2026)

The product is sold to private iX3 owners, and its interest for a fleet lies in the architecture rather than in the amount. Stream one pays for availability: 24 cents per hour connected with V2G activated, capped at €60 a month, hence €720 a year on 250 hours of connection a month, earned whether or not a single kWh moves. Stream two pays for energy: 40 cents per kWh discharged, additional and cumulative. BMW’s own footnote converts the bonus into 2,184 kWh of charging at an average 32.97 cents, which is why the offer is marketed as free driving for 12,000 to 14,000 km rather than as income. Read as a contract, the tariff discloses the unit of payment, the cap, the assumption behind the headline and the fact that the dispatch algorithm, jointly developed by BMW and E.ON, keeps the battery inside a protected operating range while the driver sets the charge targets. Because E.ON pays fixed prices, any spread between those payments and the value of the pooled grid services sits inside the tariff rather than on a separately disclosed aggregator line. For a fleet manager reading an aggregator offer, those are the items to require in the same detail, with one line added for the retained share.

BMW and E.ON published the unit, the cap and the assumption behind their headline. A fleet negotiating with an aggregator can hold the same standard of disclosure, with the retained share added to the list.

The full case

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