The Survey of TOU Rates in the United States
Design
Solar PV adoption is causing some utilities to rethink the design of
residential TOU rates
The "duck curve" introduces a need for:
-
Increased load during mid-day hours when there is excess solar PV output; and
-
Reduced load during late evening hours when PV output drops and generation must otherwise ramp up
quickly to balance the system
As a result, the TOU peak period price is being shifted later in the evening
and/or the price is being reduced during the middle of the day
APS: Revised TOU design to include a super-off-peak winter price between 10 am and 3 pm, and shifted
the peak period from noon-7 pm to 3-8 pm
Hawaii: Piloting a TOU rate with discounted mid-day price (9 am to 5 pm) and delayed peak period (5 pm to
10 pm)
California: Delaying start of peak period by five hours (new peak period definition will be 4-9 pm in San
Diego, previously started at 11 am)
SW England: Distribution utility piloted TOU rates with low mid-day price to relieve distribution system
constraints caused by high PV output
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Prepared at the Request of Counsel
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