Time-of-use rates and plug-in solar in California
Last updated
The short answer: a plug-in kit makes most of its power around midday. On a time-of-use plan, that's when electricity is cheapest, so each kWh the kit saves is worth the lower midday rate, not the expensive evening rate. SCE puts it plainly: its time-of-use plans "offer low prices while the sun is shining and solar power is contributing to the power grid."[source]
When each utility charges the most
| Utility and plan | Peak (most expensive) | Midday, when solar produces most |
|---|---|---|
| PG&E E-TOU-C[source] | 4-9 pm every day | Off-peak all day outside 4-9 pm; there is no super off-peak period |
| SCE TOU-D-4-9PM[source] | 4-9 pm (on-peak on summer weekdays, mid-peak on summer weekends and October to May) | Super off-peak 8 am-4 pm every day from October to May |
| SDG&E TOU-DR1[source][source] | 4-9 pm every day | Super off-peak 10 am-2 pm on weekdays (year-round since May 1, 2026) and midnight-2 pm on weekends and holidays |
- PG&E: E-TOU-C charges its peak rate from late afternoon into the evening every day, and has no separate super off-peak period, so midday is plain off-peak.[source]
- SCE: midday is super off-peak from October to May.[source]
- SDG&E: midday on weekdays is super off-peak all year.[source] SDG&E recently extended that weekday window from spring only to the whole year.[source]
What this means for your savings
- Expect savings at the midday rate. Our savings calculator uses your utility's off-peak rate when you pick a time-of-use plan, for this reason.
- Use power while the sun is out. Running the dishwasher or laundry around midday uses more of what your kit makes. NRG Clean Power says SB 868 creates no compensation for power you send to the grid (not yet confirmed against the enacted text), so using it yourself is what saves money.[source]
- A battery shifts some power to the evening, but it adds cost. Compare the battery's price with the difference between your peak and midday rates.
Rates and time periods change. Check your own plan on your bill or your utility's website.
Frequently asked questions
- Does plug-in solar help with the expensive evening hours?
- Not much on its own. A kit produces most of its power around midday, while the most expensive hours are in the late afternoon and evening, when solar output is low.
- Should I switch rate plans because I have a plug-in kit?
- Compare your own bills first. A small kit changes only part of your usage, so your habits matter more than the kit when choosing a plan.
Next steps
Sources
- SCE: Time-of-use residential rate plans (opens in a new tab) · checked Oct 22, 2026
- PG&E: Schedule E-TOU-C tariff (opens in a new tab) · checked Oct 22, 2026
- SDG&E: When matters (time-of-use pricing periods) (opens in a new tab) · checked Oct 22, 2026
- SDG&E: New year-round weekday super off-peak hours (April 20, 2026) (opens in a new tab) · checked Oct 22, 2026
- NRG Clean Power: SB 868 explainer (opens in a new tab) · checked Oct 20, 2026