Parties in High DERs Future Docket Respond to Draft Electrification Impact Reports of IOUs

On December 15, parties filed comments in the CPUC's High DER Future rulemaking (R.21-06-017) in response to "Draft Electrification Impacts Study Part 2" (EIS Part 2) reports submitted by PG&E, SCE, and SDG&E. (See our coverage of these reports here and here.)

The comments address the utilities’ modeling of distribution-system impacts from electrification through 2040, including projected primary and secondary grid upgrade costs, demand flexibility scenarios, and proposed approaches for integrating the study’s findings into future distribution planning and execution processes, as required by a 2024 decision (D.24-10-030).

Parties mostly agree that the draft reports represent a substantial analytical effort but also fall short of providing a reliable foundation for near-term distribution planning without further refinement and transparency. They argue that the Final Reports must:

• Clearly explain methodologies, assumptions, and data sources;
• Respond directly to party feedback; and
• Allow for a robust round of technical and implementation-focused comments before the results are relied upon in distribution planning or cost recovery.

Several parties caution that, as drafted, the studies risk being misused as de facto spending justifications rather than illustrative planning tools, particularly given rate affordability pressures and the scale of electrification-driven investment at issue.

Modeling Issues

A dominant theme is concern that the utilities’ modeling approaches (especially for the secondary distribution system) are inconsistent, overly conservative, and insufficiently aligned with modern best practices. Cal Advocates, the Utility Consumers' Action Network (UCAN), and California Community Choice Association (CalCCA) all highlight large and unexplained discrepancies among PG&E, SCE, and SDG&E in projected secondary system costs, arguing these differences stem from methodological choices rather than underlying grid realities.

Commenters criticize the reliance on deterministic “snapshot” methods, conservative thermal assumptions, and manual solutioning, which they argue systematically inflate projected upgrade needs and bias outcomes toward traditional wires solutions.

Multiple parties urge the Commission to require clearer documentation, additional sensitivities, and, in some cases, probabilistic or time-series analyses before accepting the results for planning purposes.

Undervalued Alternatives

Another critique is that demand flexibility and non-wires alternatives are undervalued or incompletely represented. Environmental Defense Fund, UCAN, and CalCCA argue that the utilities’ scenarios often exclude key tools (e.g., flexible service connections, smart panels, and more realistic Demand Response adoption pathways) or fail to account for program and administrative costs, preventing a true cost-effectiveness comparison.

This “capital-only” treatment of flexibility, commenters contend, distorts the relative economics of grid upgrades versus demand-side solutions and undermines the Commission’s modernization objectives.

Some parties recommend requiring "Total Resource Cost" perspectives, realistic participation assumptions, and clearer distinctions between load shifting and shedding to avoid overstating both risks and infrastructure needs.

Evidence of Electrification's Value

At the same time, the Vehicle-Grid Integration Council (VGIC) stresses that the draft reports nevertheless provide strong evidence of the value of electrification and, in particular, electric vehicle-enabled demand flexibility. VGIC highlights findings showing substantial avoided distribution costs driven by managed charging and vehicle-to-grid strategies. VGIC urges the Commission to build on this evidence by expanding Vehicle Grid Integration programs and ensuring that all utilities model bidirectional EVs and active charging management consistently.

INSTANT ANALYSIS: There is broad stakeholder agreement that EIS Part 2 is useful as a planning exercise, but not ready to support near-term distribution investment decisions. Parties warn that inconsistent and conservative modeling choices (particularly for the secondary system and demand flexibility) risk overstating upgrade needs and biasing outcomes toward traditional wires solutions at a time of heightened rate sensitivity.