Pioneering Commercial
Vehicle-To-Grid In
Electric School Buses
March2023

Pioneering Commercial Vehicle-To-Grid In
Electric School Buses
Results From Two Seasons Of V2GParticipation
Summary panel
In the summers of 2021 & 2022, Highland ElectricFleets & BorgWarner used vehicle-to-grid (V2G)
technology to discharge 10+ MWh hours to theMassachusetts grid over 158 hours -- the firsttime battery storage from electric school buses(ESBs) was used in a commercial V2G programin the United States. Participation generated$23k in revenue and demonstrates the value
ESBs can deliver to support the grid and lower
the cost of ownership of an electric bus fleet.

Challenges Facing The Electric Grid
Extreme weather and increasing peak loads
are challenging the electric grid’s resilienceand ability to deliver reliable electricity acrossNorth America. Recent events such as Hurricane
Ida, the Texas cold snaps in 2021 & 2023, andintensive fossil fuel peaker plants. As the gridevolves and a growing number of services
and products become electrified, electricgrids around North America will require novel
solutions to remain reliable and resilient. The
potential power available from expanding
electric vehicle (EV) fleets can help manage
disruptions as they unfold and mitigate theimpact of power outages or demand spikes oncommunities.

What Is V2G?
Vehicle-to-grid (V2G) technology allows an EV
to both draw energy from the grid (typicallyduring periods of low cost and low demand)and discharge energy back to the grid (duringperiods of higher cost and high demand).
Highland Electric Fleets (Highland) -- inpartnership with BorgWarner, Thomas Built
Buses, Proterra, and Synop -- is pioneeringcommercial V2G technology for electric schoolbuses (ESBs), which supports grid stability andreduces the cost of fleet electrification for school
districts & fleet operators.

How Can EVs Support The Grid?

the extreme heatwave of 2022 underline theneed for backup power storage. Power outages
during these events revealed the vulnerabilityof power systems that keep essential services
such as schools, nursing homes, and healthcare
facilities online. In addition, increasingly extreme
temperatures cause spikes in demand, which
necessitate firing up inefficient & carbon-V2G transforms EVs, such as electric school buses(ESBs), into mobile batteries that can be used
to help stabilize the electric grid. This class ofDistributed Energy Resources (DERs) is pivotal
to the evolution of the electric grid. Increasing
amounts of variable renewable energy cancause fluctuations on the electric grid: energy
storage, including from batteries in ESBs andother EVs, plays a critical role in balancing andbuffering the intermittency of resources likewind and solar. In addition, utilities can reduce
emissions by using electric school buses as DERs
when energy demand spikes, rather than firingup conventional fossil fuel resources for shortperiods of time.

Reducing The Cost Of Electric Fleet Ownership
Aside from helping stabilize grids with intermittent renewable energy generation and reducing
emissions, V2G technology also helps reduce energy costs associated with owning and operating
EV fleets. Bi-directional charging infrastructure typically costs more than “standard” unidirectionalchargers, as do licensing costs for the aggregator software. The Return On Investment (ROI) on thesechargers varies but is typically shortest for bigger vehicles with larger battery packs that are parked fora large percentage of the day. School buses, in particular, have the potential for the shortest ROI due
to both their battery capacity and the extended time that they are in the vehicle yard, especially given
their presence during most peak demand hours.
In addition, an increasing number of electric utilities, like National Grid, support programs that
pay electric fleets and other battery storage resources to discharge energy, turning them into
revenue-generating assets without disrupting normal operations. Highland uses private sector
financing mechanisms, bus purchasing power, expertise in project design and implementation, andmanagement of electricity costs (including V2G) to make fleet electrification easier & less expensive forschool districts & municipal entities. Highland works with partner fleet operators to pass through V2Grevenue to customers to reduce the overall cost of fleet electrification.

V2G Participation Data
In the summers of 2021 & 2022, Highland & BorgWarner piloted V2G technology using battery storage
from electric school buses. The buses discharged 10+ MWh hours to National Grid over 158 hours froman ESB depot in Beverly, Massachusetts.
Data
Summer Periods (One bus)

2Participation Days

70

Participation Hours

158

MWh to Grid

10.78

V2G Revenue$23,500

Tech & Implementation
HardwareVehicle & battery specifications
Saf-T-Liner® C2 Jouley™ electric bus by Thomas Built Bus & Proterra
Total Energy (Kwh)
220
Motor

Proterra ProDrive drivetrain; single 220kW permanent magnet drive motor

Operating Efficiency

kWh/mile - 1.4

MPGe

24.6

Range

Up to 135 – Operating range in miles usable energy/efficiency

Top Speed

65 mphHorsepower

295 peak, 170 continuous

Braking SystemRegenerative braking, air disc brakes

Charger Specifications

SoftwareBidirectional DC Fast Charging
System By BorgWarner

Vehicle & Charge Management
Software - Synop

The modular DC fast charging
system (DCFCS) from BorgWarnerconsisted of a RES-DCVC-60V2G Power Conversion System(PCS) and a RES-D2-CS20
power dispenser. The PCS unit
was installed near the 380 VAC
3-phase power input next tothe building and the dispenser
unit near the buses in theparking lot. The modular design
allowed Highland to install thedispenser up to 500 feet fromthe PCS unit. By separating the PCS from thedispenser, the DCFC is well-designed for fleet
applications where there is limited space. Bothunits are environmentally rated to NEMA 3R
and handled continuous operations outdoors
throughout the two summers during this casestudy. The bidirectional system delivered up to60kW of continuous rated DC power with an
output range of 270Vdc to 870Vdc to the electric
bus throughout the events. Optional 125kW
bidirectional DCFC are also available for larger
battery system vehicles.

Highland uses Synop as the vehicle and charge
management platform powering Highland
Dashboard. This software integrates with key
ecosystem components (vehicle, charger, andutility) that enable V2G transactions. V2G eventswere triggered manually in the 2021 season andvia the platform in 2022. The platform receives
prompts from National Grid for a specified
time period, then validates the vehicles’ fleet
charging schedule to ensure excess capacity.
Once validated, the Synop platform delivers theappropriate charging schedule to the chargers
via the OCPP, and energy is discharged fromthe battery back to the grid. Highland & Synop
monitor this discharge in real time and generatereports to validate the V2G event.

The PCS and dispenser units
are certified to UL-1741-SA andincorporate galvanic isolation tomeet the utility’s requirementsfor putting power back into thegrid. Highland and BorgWarnerused Open Charge Point Protocol(OCPP) as the application
protocol to communicate
between Highland’s energy
operator and the charging
station, control when the bus
should charge, and provide
power to the grid. To initiate a discharge event,the utility communicated the energy discharge
requirements, which Highland then dispatchedto the charging station

About BorgWarner
For more than 130 years, BorgWarnerhas been a transformative global productleader bringing successful mobility innovation
to market. Today, we’re accelerating theworld’s transition to eMobility — to help build
a cleaner, healthier, safer future for all.

About Highland Electric Fleets
Highland Electric Fleets is the leading
provider of fleet electrification-as-a-service formunicipal and government fleets in NorthAmerica. Active in 30 states and Canada,
Highland is responsible for the largest electric
school bus deployment in the United States.