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Southern California Edison (SCE), Pacific Gas & Electric (PG&E), and San Diego Gas & Electric (SDG&E) all released new tariff rates on January 1, 2020, improving the economics of residential solar for all three utilities.

SCE - 20% increase in avoided cost of power (ACP)

For residential solar developers, the highlight was the much-anticipated redesign of the default residential post-solar tariff TOU-D-4-9PM. The result was a result was a 19-23% increase in the avoided cost of power (ACP), depending on the region within SCE’s service territory.

While both delivery and generation costs increased with the January 2020 tariff version, it was the rebalancing of time-of-use (TOU) generation prices that drove the increase in ACP. In the chart below, you see that the price difference between the TOU periods has narrowed and in particular the winter super off-peak price has increased 31%. The increase in the summer off-peak (9 PM - 4 PM) and winter super off-peak (8 AM - 4 PM) is particularly helpful for solar developers, as it coincides with peak solar production.

PG&E - Closes E-TOU-A, E-TOU-C new default post-solar tariff

On January 1, 2020, Pacific Gas & Electric closed E-TOU-A to new subscribers. With the closing of E-TOU-A in 2020, the new default post-solar tariff will be E-TOU-C. The primary difference between E-TOU-A and E-TOU-C lies in the TOU definitions. While both tariffs have a 4 PM to 9 PM peak period, E-TOU-C extends the on-peak period into weekends and holidays, whereas E-TOU-A limits the on-peak period to weekdays.

In addition, there are small differences in the TOU rates (see table below).

The overall impact of the switch from E-TOU-A to E-TOU-C on the avoided cost of power (ACP) for PG&E is negligible. ACP increased in seven baseline regions between 0.1 and 0.3¢ while ACP remained identical for four baseline regions.

Genability has not yet set the closed date on E-TOU-A in order to allow our customers to continue to quote projects that received interconnection approval before January 1, 2020. We will be adding the closed date on April 1, 2020. In the meantime, we have added “Closed” to the tariff name and made E-TOU-C the most popular solar-eligible residential tariff to direct solar developers to the best post-solar tariff.

SDG&E - Nears end of TOU transition

On March 1, 2019, San Diego Gas & Electric began its year-long process to transition its customer base from their previous default tariff DR to their new default tariff with TOU pricing TOU-DR1. Genability has updated its customer counts to reflect this transition, and you will now see TOU-DR1 as the default pre-solar and post-solar tariff for SDG&E.

Switching the pre-solar tariff from DR to TOU-DR1 increases the ACP for SDG&E by between 0.6 and 0.7¢/kWh due to the higher, pre-solar costs.

John Tucker

John Tucker is Senior Director of Data Analytics at Arcadia and former Vice President of Data & Operations at Genability (now part of Arcadia).

Woodstock, VT