Vehicle-to-grid turns a parked EV into a dispatchable battery—exporting DC through a bidirectional charger/inverter stack when the grid or aggregator pays more than it costs to refill later. The idea is simple; the contracts, interconnection rules, and battery warranty math are not. V2G is real economics in pilot form, not fantasy, but only where utilities and ISOs allow export and compensate it.
What has to exist on site
- A V2G-capable vehicle platform and OEM warranty terms for discharge cycles
- UL-listed bidirectional hardware with utility approval
- Interval metering and a program enrollment (utility VGI, aggregator, or fleet tariff)
Revenue stacks
Programs may pay for capacity (available kW), energy (kWh delivered), or both. Frequency regulation wants fast response; peak shaving wants sustained export. Revenue differs by market—California pilots differ from Texas nodal markets.
Cycle wear vs. dollars in
Every discharge adds calendar and cycle aging. Owners must net tariff revenue minus accelerated degradation—often modeled as cents per kWh round-trip. Conservative drivers cap daily export depth and preserve a commute buffer the app enforces.
Carbon and sustainability reporting
Fleet operators stack renewable energy credits or avoided-emissions claims when discharged kWh displaces marginal peaker plants. Methodology matters: baseline grid emissions factor by hour, not annual average, if you want defensible reports.
Risks and fine print
- Interconnection limits on export
- Transformer backfeed rules in your neighborhood
- Tax treatment of energy sales vs credits
- Program curtailment when the grid does not call you
Near-term practical path
Start with managed charging (V1G)—shift import to off-peak without export risk. Add export when your utility publishes a residential or fleet V2G tariff with published compensation tables. Pilot one vehicle, log SOC daily, and compare paid export to warranty guidance.
V2G money is grid-program money first, EV hardware second. Read the tariff, model battery wear honestly, and treat carbon benefits as reporting icing—not the core business case until revenue proves out.