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The Maryland Public Service Commission (PSC) has unanimously voted to adopt a comprehensive suite of vehicle-to-grid (V2G) interconnection rules for both DC and AC systems, becoming the first US state to do so.
The rules were set by the Vehicle-Grid Integration Council (VGIC) in the US, an advocacy group committed to advancing the role of EVs and smart EV charging.
Updated in the Code of Maryland Regulations (COMAR) 20.50, the guidelines – which cover both AC and DC systems – now include the following key provisions:
- The V2G system is defined, not using the terms ‘V2G-Capable Electric Vehicle (EV)’ or ‘V2G-Capable Electric Vehicle Supply Equipment (EVSE)’.
If these terms were used, says VGIC, it could inadvertently require all vehicles capable of bidirectional charging to request a utility interconnection agreement regardless of whether a customer has made any investments or plans to use their system in bidirectional mode when operating in parallel to the grid.
- All V2G DC systems (systems with a stationary inverter) are subject to the existing rules for stationary energy storage.
This is consistent with treatment of V2G DC systems in California’s Rule 21, Massachusetts, New York, Colorado, and other states.
- All V2G AC systems (systems where the inverter capabilities are onboard the vehicle) can seek interconnection with the utility under one of two pathways.
According to VGIC, this is a major step forward for the V2G industry, as it allows products to move through either certification process with the certainty that whichever pathway is chosen will be accepted onto the utility grid as a safe, reliable customer-sited energy resource.
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- Bidirectional charging systems for backup power are not routed through a lengthy interconnection study process.
Rather, customers using bidirectional charging systems in this manner need to notify the utility of the existence and location of these backup power systems. Meanwhile, customers using their charging systems in bidirectional mode when operating in parallel with the grid must move through the utility interconnection process to ensure safe and reliable grid operation.
Similarly, bidirectional charging systems may be installed and operate in load-only mode until a customer wishes to enable grid-parallel bidirectional charging operation, at which point the customer must first request utility interconnection.
This allows customers to instal and use future-proofed charging stations even before a V2G programme or rate is established.
For example, school bus operators can electrify their fleets with bidirectional charging equipment and transport students without having to wait for a bidirectional charging system to move through an often lengthy interconnection process.
Rates and regulatory certainty
Maryland’s new interconnection rules stem from the state’s Distributed Renewable Integration and Vehicle Electrification (DRIVE) Act (H.B. 1256), which went into effect October 2024.
The law also directs the utilities to propose compensation mechanisms for DERs, including V2G systems. Utilities are set to file applications with the Commission on June 30, 2025.
According to VGIC, the new V2G interconnection rule is a watershed for those developing bidirectional charging systems, including automotive original equipment manufacturers (OEMs) and charging manufacturers.
Specifically, organisations working toward scalable V2G AC systems, wherein the inverter functions are onboard the vehicle, are given a clear signal to proceed in developing systems that work best for their respective business models.
Technology providers are now in a race, says the Council, to develop, test, and deploy these systems to ensure customers can leverage their EV batteries for more than just mobility.
Maryland’s new V2G interconnection rules will officially go into effect on July 7, 2025.
