Figure

SCE default time-of-use rate versus the flat rate

On SCE's default TOU-D-4-9PM rate, the cheapest hours (summer off-peak and winter midday) cost about 35 and 34 cents per kWh, close to the flat Schedule D average of about 34 cents, while the summer 4-to-9 PM peak costs about 58 cents (72% more). The design surcharges the summer evening rather than discounting midday.

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This figure is from the Southern California Edison case study, a primary-source look at how California procured storage and what pointing the same playbook at demand would add.

Last updated: 2026-07-03.