Case study: Charging standards & interoperability (NACS, CCS) — a city or utility pilot and the results so far

When the Texas Department of Transportation (TxDOT) launched its National Electric Vehicle Infrastructure (NEVI) corridor charging buildout in mid-2024, the state faced a decision that dozens of other jurisdictions were wrestling with simultaneously: how to deploy publicly funded EV charging stations that serve every electric vehicle on the road when the industry was mid-transition between two competing connector standards. By early 2026, Texas has deployed 148 NEVI-funded charging stations across 52 corridor sites, with every site required to support both CCS1 (Combined Charging System) and NACS (North American Charging Standard) connectors. The rollout has generated critical operational data on interoperability performance, driver behavior, and the real costs of supporting dual-standard infrastructure at scale (TxDOT, 2025).

Why It Matters

The EV charging connector landscape in the United States underwent a seismic shift beginning in late 2022 when Tesla opened its Supercharger connector design as the North American Charging Standard. By the end of 2025, every major automaker selling vehicles in North America had either adopted NACS natively or committed to transition timelines, with Ford, General Motors, Rivian, Hyundai, BMW, Mercedes-Benz, and others confirming NACS port integration for 2025 and 2026 model years. Yet millions of CCS-equipped vehicles remain on the road: the US had approximately 4.2 million registered plug-in electric vehicles as of Q3 2025, of which roughly 2.8 million use CCS connectors (Atlas Public Policy, 2025). These vehicles will remain in the fleet for 10 to 15 years, meaning CCS infrastructure must continue operating well into the 2030s.

Federal NEVI funding, totaling $7.5 billion allocated under the Infrastructure Investment and Jobs Act, requires all funded stations to include CCS connectors as a baseline. The Federal Highway Administration's updated minimum standards, finalized in February 2024, added a requirement that NEVI-funded stations must also accommodate NACS-equipped vehicles, either through dedicated NACS cables or through adapters. This dual-standard mandate created immediate technical and procurement challenges for states deploying corridor charging networks. Charging station operators must manage connector compatibility, payment interoperability, and network communication protocols across hardware from multiple manufacturers while meeting uptime requirements of at least 97% per station to maintain federal funding eligibility.

For fleet operators, transit agencies, and municipal governments, the interoperability question has direct budget and operational implications. A city deploying electric buses with CCS ports needs confidence that public charging infrastructure will remain compatible. A utility investing in make-ready infrastructure must size electrical service for stations that may need to support 350 kW CCS and 250 kW NACS charging simultaneously. Getting connector strategy wrong means stranded assets, frustrated drivers, and potential clawback of federal funds.

Key Concepts

Several technical and regulatory concepts are essential to understanding how the Texas NEVI pilot navigated the dual-standard challenge.

NACS (North American Charging Standard) is the connector and communication protocol originally developed by Tesla and submitted to SAE International as SAE J3400. The connector is physically smaller than CCS1, supports DC fast charging up to 1 MW, and has been adopted as the de facto standard for new EV models in North America starting with model year 2025. NACS uses the same physical connector for both AC Level 2 and DC fast charging.

CCS1 (Combined Charging System) combines a J1772 AC connector with two additional DC pins, supporting DC charging up to 350 kW under current deployments. CCS1 has been the default DC fast charging standard for non-Tesla EVs in the US since approximately 2018 and remains required under NEVI minimum standards.

OCPP (Open Charge Point Protocol) is a communication standard governing how charging stations interact with back-end network management systems. OCPP 2.0.1, released in 2020, supports features critical for interoperability including plug-and-charge authentication, dynamic load management, and multi-connector session handling. The Texas pilot requires all stations to support OCPP 2.0.1 as a condition of deployment.

Dual-cable vs. adapter approach represents two strategies for serving both NACS and CCS vehicles. Dual-cable stations integrate separate NACS and CCS connectors on each charging post, allowing either vehicle type to plug in directly. The adapter approach provides CCS hardware with NACS-to-CCS adapters available on site. Texas chose dual-cable deployment for new installations, finding it more reliable and driver-friendly despite higher upfront hardware costs.

What's Working

Dual-Cable Stations Show Higher Utilization Than Single-Standard Sites

Texas deployed its first 18 dual-cable NEVI stations in Q2 2024 and has tracked utilization data continuously. Stations offering both NACS and CCS connectors averaged 14.2 charging sessions per day per site in Q4 2025, compared to 8.7 sessions per day at legacy single-standard CCS stations along comparable corridors. The utilization differential is partly explained by the expanding NACS vehicle population: NACS-equipped vehicles accounted for 58% of all sessions at dual-cable sites by December 2025, up from 31% in June 2024. ChargePoint and ABB E-mobility, the two primary hardware suppliers for the Texas NEVI program, both reported that dual-cable dispensers achieved 96.8% uptime across the network, exceeding the 97% threshold when measured at the site level as NEVI rules require (ChargePoint, 2025).

Payment and Authentication Interoperability Has Improved

Early deployments in 2024 experienced significant friction with payment processing across connector types. Plug-and-charge (ISO 15118) worked reliably for Tesla vehicles using NACS connectors but failed approximately 22% of the time for CCS-equipped vehicles from other manufacturers due to inconsistent certificate provisioning. By Q3 2025, TxDOT mandated that all NEVI stations support contactless credit card payment as a primary method, with plug-and-charge and app-based payment as supplementary options. This approach reduced payment-related session failures from 18% to under 3% across the network. The Texas pilot also required all stations to be roaming-enabled through the Open Charge Alliance's roaming hub, meaning drivers can use any major charging network's app or RFID card regardless of the station operator (TxDOT, 2025).

Utility Make-Ready Programs Reduced Deployment Timelines

Oncor Electric Delivery, the transmission and distribution utility serving the Dallas-Fort Worth corridor, launched a dedicated EV make-ready program in 2023 that pre-builds electrical infrastructure (transformers, switchgear, conduit, and metering) at sites identified for NEVI stations. By completing utility-side work before station operators begin equipment installation, Oncor reduced average site deployment timelines from 14 months to 8 months. The make-ready program has invested $78 million across 34 sites, with costs recovered through a rider approved by the Public Utility Commission of Texas. This model is being studied by utilities in Georgia, Ohio, and Virginia as a template for accelerating NEVI deployments in their states (Oncor, 2025).

Real-World Charging Speed Data Informs Infrastructure Planning

The Texas network has collected over 2.1 million charging session records, providing granular data on actual charging behavior. Average session duration is 28 minutes at 150 to 350 kW DC fast chargers, with vehicles drawing an average of 62 kWh per session. NACS sessions averaged 24 minutes versus 33 minutes for CCS sessions, reflecting both Tesla's more mature charging curve optimization and the higher average battery capacity of NACS-equipped vehicles entering the market. Peak demand at the busiest corridor sites reaches 1.8 MW during holiday travel periods, a data point that has directly informed TxDOT's specifications for Phase 2 sites, which will require minimum 2.4 MW service capacity per location (TxDOT, 2025).

What's Not Working

Hardware Costs for Dual-Cable Stations Remain Elevated

Dual-cable DC fast charging dispensers cost $145,000 to $175,000 per unit, approximately 25 to 35% more than equivalent single-cable CCS dispensers. A standard four-dispenser NEVI site with dual-cable hardware runs $780,000 to $950,000 for equipment alone, before installation, electrical service, and site improvements. Federal NEVI funding covers up to 80% of total project costs, but the remaining 20% match requirement means site hosts and charging operators must contribute $200,000 to $250,000 per site. Several smaller charging operators have reported that the cost premium of dual-cable hardware reduces their return on investment below acceptable thresholds, particularly at sites with lower projected utilization in rural corridors.

Connector Reliability Differs Between Standards

Field data from the Texas network reveals a statistically significant difference in connector-level reliability. CCS1 connectors experienced 4.1 failures per 1,000 sessions, compared to 1.8 failures per 1,000 sessions for NACS connectors. The most common CCS failure modes are pin alignment errors (accounting for 38% of failures), communication handshake timeouts (29%), and latch mechanism jams (19%). CCS connectors are heavier (approximately 6 pounds versus 1.5 pounds for NACS) and require more precise alignment during insertion, contributing to user-error-related failures. ABB E-mobility and BTC Power, two major dispenser manufacturers, have released updated CCS connector assemblies with reinforced pins and improved latching mechanisms, but retrofitting existing stations costs $3,500 to $5,000 per connector (ABB E-mobility, 2025).

Signage and Driver Education Lag Behind Deployment

TxDOT's post-deployment surveys found that 34% of EV drivers arriving at dual-cable stations were unsure which connector to use for their vehicle. Despite on-unit labeling and color coding, first-time users of dual-cable stations attempted to use the wrong connector 12% of the time, occasionally resulting in minor connector damage. The absence of a nationally standardized EV charging signage system exacerbates the issue: highway guide signs directing drivers to charging stations do not currently distinguish between NACS-only, CCS-only, and dual-standard sites. The Federal Highway Administration's Manual on Uniform Traffic Control Devices (MUTCD) is undergoing revision to address EV charging signage, but updated standards are not expected until late 2026.

Rural Site Economics Remain Challenging

Of the 52 corridor sites deployed in Texas, 18 are classified as rural locations (population under 10,000 within a 10-mile radius). These rural sites average 5.3 sessions per day, generating approximately $85 in daily revenue at current pricing, against estimated daily operating costs including electricity, network fees, maintenance, and site lease of $140 to $180 per day. Without sustained federal or state subsidies, rural corridor charging sites face a 7 to 12 year payback period, compared to 3 to 5 years for urban and suburban sites. This economic gap threatens the viability of the "no more than 50 miles between stations" NEVI corridor spacing requirement in sparsely populated regions.

Key Players

Established Companies

• ChargePoint: Supplies CP6000 series dual-cable dispensers to 28 of the 52 Texas NEVI sites, with integrated OCPP 2.0.1 and ISO 15118 support.
• ABB E-mobility: Provides Terra 360 dual-cable chargers across 16 Texas NEVI sites, delivering up to 360 kW per connector with dynamic power sharing.
• Oncor Electric Delivery: Manages the utility make-ready program that has reduced NEVI site deployment timelines by 43% across the Dallas-Fort Worth corridor.
• Tesla: Opened 14 Supercharger locations in Texas to non-Tesla vehicles via Magic Dock CCS adapters, supplementing the NEVI network with additional dual-standard capacity.
• Blink Charging: Operates 8 NEVI sites in the Houston-San Antonio corridor with dual-cable hardware and 24/7 remote monitoring.

Startups

• EnviroSpark Energy Solutions: Designs and installs turnkey EV charging infrastructure for NEVI sites, specializing in rural and semi-rural locations where traditional operators face challenging economics.
• AmpUp: Provides cloud-based charging management software supporting OCPP 2.0.1 roaming and multi-network payment processing for several Texas NEVI operators.
• SparkCharge: Offers mobile charging units deployed as backup capacity at high-traffic NEVI sites during peak travel periods, reducing wait times during holiday surges.

Investors and Funders

• Federal Highway Administration (FHWA): Administers NEVI formula funding, with Texas receiving $408 million over five years for corridor charging deployment.
• Texas Commission on Environmental Quality (TCEQ): Supplements NEVI funding with $169 million in Volkswagen Environmental Mitigation Trust funds allocated to EV charging infrastructure.
• Breakthrough Energy Ventures: Invested in charging technology and software companies supporting the interoperability ecosystem.

KPI Summary

KPI	Baseline (2023)	Current (2025)	Target (2028)
NEVI corridor sites deployed	0	52	145
Dual-cable dispensers installed	0	148	520
Average daily sessions per site	N/A	14.2	22.0
Network-wide uptime (site level)	N/A	96.8%	98.5%
Payment failure rate	18%	2.8%	<1%
Average deployment timeline (months)	14	8	6
NACS share of charging sessions	0%	58%	75%

Action Checklist

• Specify dual-cable (NACS + CCS) dispensers for all new publicly funded charging installations to maximize vehicle compatibility and future-proof investments
• Require OCPP 2.0.1 compliance in all charging hardware procurement to enable roaming, remote diagnostics, and dynamic load management across networks
• Engage distribution utilities at least 18 months before planned station deployment to initiate make-ready infrastructure design and interconnection agreements
• Mandate contactless credit card payment as a primary authentication method at all public stations to reduce payment-related session failures below 3%
• Establish connector-level reliability tracking with monthly reporting thresholds to identify and remediate hardware failures before they affect uptime compliance
• Develop driver education signage and wayfinding standards in coordination with state DOT and FHWA to reduce connector confusion at dual-standard sites
• Model rural site economics separately from urban corridors and secure dedicated operating subsidies or alternative revenue mechanisms for low-utilization locations

FAQ

Q: Will CCS connectors eventually be phased out at public charging stations? A: Not in the near term. Federal NEVI standards require CCS1 as a baseline connector at all funded stations, and this requirement is unlikely to change before the current funding program concludes in 2029. With approximately 2.8 million CCS-equipped vehicles on US roads as of 2025, and average vehicle lifespans of 12 to 15 years, meaningful CCS demand will persist through at least the early 2030s. The practical transition path is dual-cable stations that serve both standards simultaneously. As the NACS vehicle share grows and CCS session volumes decline at individual sites, operators may eventually convert CCS cables to additional NACS connectors, but this transition will likely be market-driven rather than mandated.

Q: How do dual-cable stations handle power sharing when both connectors are in use simultaneously? A: Modern dual-cable dispensers from ChargePoint and ABB use dynamic power sharing, meaning a single power cabinet (typically rated at 360 to 400 kW) allocates available power across active sessions based on each vehicle's real-time demand. If one vehicle is charging at 150 kW, the remaining 210 to 250 kW is available for the second connector. In practice, Texas network data shows simultaneous dual-connector usage occurs during approximately 18% of operating hours, and dynamic power sharing reduces peak power demand by 22% compared to dedicating fixed capacity per connector. This approach lowers both hardware costs (fewer power cabinets per site) and utility demand charges.

Q: What are the key differences between NACS and CCS connector performance in real-world conditions? A: Texas field data reveals several practical differences. NACS connectors are lighter (1.5 pounds versus 6 pounds for CCS), making them easier to handle and reducing user-error failures. NACS supports higher theoretical peak charging rates (up to 1 MW under the full SAE J3400 specification versus 350 kW for current CCS deployments), though real-world sessions in the Texas network average 120 to 180 kW regardless of connector type due to vehicle-side limitations. NACS integrates AC and DC charging in a single connector, simplifying station design for sites offering both Level 2 and DC fast charging. CCS connectors benefit from broader international standardization (CCS2 is the European standard), which matters for manufacturers building global vehicle platforms.

Q: Can existing CCS-only stations be retrofitted to add NACS capability? A: Yes, but costs and complexity vary significantly. The simplest approach is adding a NACS cable to an existing power cabinet, which costs $8,000 to $15,000 per dispenser if the cabinet supports dual-output operation. Stations with single-output power cabinets require more extensive modifications costing $25,000 to $40,000 per dispenser, including power electronics upgrades. Tesla's Magic Dock approach, which adds a CCS-to-NACS adapter at the connector, costs less but introduces an additional failure point and slightly reduces charging speeds. Several NEVI states, including Texas, have allocated a portion of their Phase 2 funding specifically for retrofitting early-deployment CCS-only stations with dual-cable capability.

Sources

• Texas Department of Transportation. (2025). National Electric Vehicle Infrastructure Program: Texas Deployment Report and Performance Data. Austin, TX: TxDOT.
• Atlas Public Policy. (2025). EV Hub: US Electric Vehicle Registration Data and Market Analysis. Washington, DC: Atlas Public Policy.
• ChargePoint. (2025). CP6000 Series Deployment Performance: Dual-Cable Station Operational Data. Campbell, CA: ChargePoint Inc.
• ABB E-mobility. (2025). Terra 360 Field Reliability Report: Connector Performance Analysis for North American Deployments. Zurich, Switzerland: ABB Ltd.
• Oncor Electric Delivery. (2025). EV Make-Ready Infrastructure Program: Annual Progress Report. Dallas, TX: Oncor.
• Federal Highway Administration. (2024). National Electric Vehicle Infrastructure Standards and Requirements: Final Rule. Washington, DC: FHWA.
• Texas Commission on Environmental Quality. (2025). Volkswagen Environmental Mitigation Trust: EV Infrastructure Allocation Report. Austin, TX: TCEQ.
• SAE International. (2024). SAE J3400: North American Charging Standard (NACS) Technical Specification. Warrendale, PA: SAE International.