​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 7% 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.
• The statutory compliance target keeps climbing. The Clean Peak Standard will rise from 7% 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 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.

Contracted renewables earn a fraction of a BESS’s credit

The Department of Energy Resources assumes Existing and Contracted resources already recover their costs through another state mechanism, so it doesn't pay them twice through Clean Peak. The largest renewable resources contribute almost nothing to compliance supply, no matter how much capacity gets built.

Clean Peak credit is the majority of a BESS’s evening revenue at every tier

The same 100 MW / 4h merchant BESS earns identical day-ahead energy revenue from one summer Seasonal Peak Period evening regardless of which Clean Peak tier it qualifies for. A hypothetical battery earns $20,000 from charging overnight and discharging into the window. The only difference is the Clean Peak credit stacked on top of that.

A SMART ES BESS (0.3x) earns $52,000 for the evening; a merchant BESS (1.0x) earns $124,000; a new, distribution-connected Near-term Resource (2.0x) earns $228,000. Clean Peak credit is 61% of that total at the SMART ES tier, rising to 84% for merchant and 91% for Near-term -- in every case, the certificate is the larger part of the BESS’s revenue, not a bonus stacked on top of it.

What this means for market participants

The Clean Peak compliance obligation rises every year. That widening obligation is what keeps pushing the program's dollars toward merchant BESS developers. CPEC is an incentive to build batteries in the near term to capture the near-ACP ceiling prices in place from 2026 through 2032, while reducing energy price spikes and cleaning up peak resources.

For regulators, this program indirectly supports renewables by building storage resources that would reduce curtailment, and protects consumers by creating more supply in peak periods. For Massachusetts BESS developers, this is a structural price support for BESS to develop in the state, with a quasi-capacity price support.