Fundamentals · 6 min read

What is V2G (vehicle-to-grid)?

Vehicle-to-grid, usually shortened to V2G, is the practice of discharging a parked electric vehicle's battery back into the electricity grid instead of only charging it. It turns a fleet of idle batteries into a dispatchable energy resource.

How bidirectional charging works

An ordinary EV charger moves power in one direction: from the grid, through the charger, into the vehicle. A bidirectional charger adds an inverter path that can run the flow the other way, converting the vehicle's DC battery output back to grid-synchronised AC.

The conversion happens either in the charger (DC bidirectional, the common approach for CHAdeMO and CCS V2G equipment) or on board the vehicle (AC bidirectional, used by several newer platforms). Either way the site needs equipment certified to interconnect and disconnect safely — UL 9741 for the bidirectional charging equipment itself and UL 1741 SB for the grid-interactive inverter behaviour.

Control is what makes it useful. A site controller decides when to charge, when to hold, and when to export, based on tariff windows, the property's own load and signals from a utility or grid programme.

The three things V2G is actually paid for

Demand-charge reduction: discharging into your own building load during the monthly peak lowers the demand charge that often makes up the largest single line on a commercial power bill.
Energy arbitrage: charge when energy is cheap, discharge or avoid buying when it is expensive, under time-of-use or real-time tariffs.
Grid services: capacity, demand response and ancillary-service programmes pay for a resource that can be dispatched on request. Aggregation matters here — one vehicle is noise, a few megawatts is a grid asset.

Why dwell time decides feasibility

A vehicle can only export while it is plugged in. That makes V2G economics a function of how long batteries sit still, not how many vehicles pass through. Highway fast-charging sites have terrible dwell time; marinas, boat storage yards, campgrounds, RV resorts and residential garages have excellent dwell time.

This is why GridLynQ focuses on properties where vehicles, boats and rigs are parked for days or weeks. The battery is already there, already idle, and already connected to a pedestal.

What about battery wear?

Cycling a battery does age it, and manufacturers vary in how they treat bidirectional discharge under warranty. Well-designed programmes limit depth of discharge, keep the state of charge inside a conservative band, and guarantee the vehicle is at a set charge level by a departure time.

Check the specific manufacturer's warranty language before enrolling customer vehicles. Site-owned stationary storage, which GridLynQ deploys alongside bidirectional pedestals, carries none of this ambiguity and does much of the heavy lifting.