Concord Municipal Light Plant board approves vehicle-to-grid pilot rate for school buses

The Concord Municipal Light Plant board on June 18 voted unanimously to approve a vehicle-to-grid (V2G) pilot tariff designed to compensate electric bus operators for returning energy to the grid during system peaks.

Laura, a CMLP staff member who presented the tariff, said the schedule “specifies what CMLP will charge a customer for charging a battery” and “also specifies what CMLP is going to compensate them when they push energy back from the battery to the grid.” The board approved the tariff following a short public comment period and a roll-call vote in which Warren Leon, Nicole Brosner, Tyson Kamchinsky, Chris Schoffner and Chair John Dalton recorded “yes.”

The tariff as presented applies to electric vehicle bus battery systems and is structured as a pilot. Key economic features described by Laura include a medium-general-service meter charge of $90 per month for the pilot (the tariff is aimed at chargers around 66 kW), a demand-related charge referenced at $183 (non-coincident peak demand), and an energy credit for returned energy calculated using a revised methodology that yields a 6¢/kWh compensation (staff explained the change from an earlier 5.5¢ estimate was driven by excluding super off-peak hours and focusing compensation on peak-targeting hours and historical ISO peak windows). Capacity-related credits described in the presentation include $56 per kW-year and a $14 per kW-month transmission-related credit; staff said those values reflect the CMLP’s assessed capacity and transmission costs.

Board members pressed staff on three points before the vote: whether non-participating customers benefit from the tariff, what the pilot’s goals are, and whether other customers could qualify. Laura said the compensation is aligned with market prices, noting a small administrative “haircut” to cover manual crediting, and that the pilot is intended to “recognize the value that the bus or any battery is putting back onto the grid” while acknowledging buses must remain primarily available for transportation service. The tariff is narrowly written so CMLP must approve other participants.

Dean Banfield, the town liaison, asked whether peak-identification would be handled by CMLP or third-party vendors; staff said the grant program supporting the chargers brought in a peak-finding vendor but questioned whether customers would continue to retain that expertise absent grant support. Laura said customers may terminate participation with 60 days’ notice and that any credits that are assessed after the fact (for example, capacity credits determined year-end) would be paid retroactively for the period the participant was enrolled.

During public comment Pamela D. urged the town to accelerate programs that enable batteries to discharge to the grid and cited interest in building a virtual power plant; Brian urged staff to review lessons after a year of operation. Both comments were acknowledged by staff.

The board directed staff to publish the pilot’s methodology and present findings to the board as meter-data analysis becomes available. Laura and Jason said they expect to collect at least a full year of data (the capacity values are assessed after the calendar year) before drawing firm conclusions about value and scalability.

What happens next: the tariff is approved and CMLP staff will implement the pilot terms, publish the analysis and return to the board with data and recommendations after operating the pilot and reviewing at least one year of results.