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What is Standard Supply Service (SSS)?

Standard Supply Service (SSS) is the default electricity supply purchased by customers who are not on a competitive generation contract. In most jurisdictions, SSS includes a mix of resources (fossil, nuclear, hydro, and renewable energy procured for compliance programs like RPS).

For Scope 2 market-based accounting, SSS matters because it can carry embedded carbon-free attributes that customers already pay for through retail rates.

Why SSS matters in Scope 2 accounting​

  • Location-based method: Uses grid-average emissions and does not depend on supplier choices.
  • Market-based method: Can use supplier-specific emission factors (SSEFs), where SSS clean attributes can reduce reported emissions.

Core SSS value proposition​

  • Claim what you already fund: Pro-rata allocation of SSS carbon-free energy can reduce residual emissions.
  • Audit-ready defensibility: Claims are backed by supplier attestations, public data, and transparent calculations.
  • Integrity controls: Anti-shuffling and double-counting safeguards are built into the methodology.
  • Pathway to deeper decarbonization: SSS can establish a baseline, then be supplemented with time-matched procurement where needed.

Practical calculation concept​

A common pro-rata approach:

Claimable CFE MWh = (Total SSS CFE MWh / Utility Retail Sales MWh) × Customer Load MWh

This enables fair allocation of default-supply clean attributes across customers in a service territory.

How SSS Registry helps​

  • Consolidates methodology, supplier data, and quality checks
  • Produces exportable, audit-ready reporting outputs
  • Improves consistency and traceability across reporting cycles
  • Supports migration from proxy estimates to verified supplier data over time