​Massachusetts wants clean generation running during its highest-demand hours to avoid the most expensive and polluting generation. The Clean Peak Energy Standard (CPS) enforces that through the Clean Peak Energy Certificate (CPEC), a compliance credit that distribution utilities must purchase. That target already covers 4% of distribution utility load in 2026, climbing to 34% by 2034.

Each technology has an earning multiplier that is multiplied by the seasonal earning rate. So, Massachusetts discounts contracted renewables to just 0.01x the relevant CPEC earning multiplier. SMART solar and Section 83C offshore wind contracts earn a 0.01x multiplier, against 1.0-2.0x for merchant battery energy storage (BESS).

This means that the continued addition of solar or offshore wind barely grows the compliance supply as a result. This has meant that historically, real-world CPECs have cleared around 87% of the $65 Alternative Compliance Payment (ACP) ceiling. This discount to the ACP ceiling is due to a number of reasons, including a state-mandated discount for long-term CPEC procurement contracts, as well as a haircut that covers transaction fees and risk.

Key takeaways

• Contracted renewables earn 1% of what a merchant BESS earns. MA CPS sets the Contracted Resource multiplier at 0.01x for SMART solar and Section 83C offshore wind.
• The CPEC credits award discharge during peak periods which are already the highest-priced hours (on average). BESS would already generally discharge during the regulated periods, but can now earn significant multipliers on that discharge. There is no impact on the charging periods and the cheapest charging window varies by season.
• An early-2026 emergency amendment cut the near-term ramp, meaning the Clean Peak Standard now rises from 4% of distribution utility territory retail sales load in 2026 to 34% by 2034, then 1.5% a year through 2050.
• New batteries can earn double the credit of a merchant BESS. A distribution-connected Near-term Resource earns 2.0x, on top of a separate potential 25x multiplier for discharging during the month's single coincident system peak hour.

The Seasonal Peak Period shapes the discharge profile of BESS

Massachusetts calculates CPEC awards through a stack of multipliers set out in their regulation. Before any of the multipliers apply, a resource has to discharge during the Seasonal Peak Period. The period is a set evening window that shifts with the season, on business days only (Mon–Fri, excluding state and federal holidays). Output inside that window earns a seasonal quantity multiplier, while output outside it earns no additional credit.

The Massachusetts Department of Energy Resources sets the season dates, Seasonal Peak Period, and the quantity multipliers. The windows are the cheapest 4h blocks for a hypothetical merchant BESS, based on average hourly ISO-NE day-ahead prices.

Contract status and timing, not technology, decide a project's multiplier tier

Seasonal peak multipliers apply before resource multipliers. The criteria in the table below outline the resource multipliers. Multipliers generally scale based on the level of state support already applied to a given resource.