Guide
Southern California Time-of-Use Rates, Explained
If you live in Orange County or San Diego, the time of day you use electricity matters as much as how much you use. Here's how time-of-use (TOU) pricing works on SCE and SDG&E, and how solar plus battery storage turns those peak hours into savings.
What is a time-of-use rate?
A time-of-use rate charges different prices per kilowatt-hour depending on the time of day, the day of the week, and the season. Both Southern California Edison (SCE) and San Diego Gas & Electric (SDG&E) have moved most residential customers onto TOU plans by default. Power costs the most during "peak" hours — the late afternoon and early evening — when grid demand is highest.
That's a problem for traditional grid users, because peak hours are exactly when people get home, run AC, cook dinner, and charge EVs. But it's an opportunity if you have solar and a battery.
SCE peak hours (Orange County)
Most SCE residential customers are on TOU-D-4-9PM or TOU-D-5-8PM. As the plan names suggest:
- TOU-D-4-9PM: on-peak is 4–9 p.m. every day, with higher summer pricing from June through September.
- TOU-D-5-8PM: on-peak is 5–8 p.m. every day, with a smaller peak window but a higher baseline rate.
- TOU-D-PRIME: built for EV and battery owners — cheaper overnight "super off-peak" pricing, steeper 4–9 p.m. peak.
Summer peak rates on SCE often land in the $0.55–$0.75 per kWh range, while off-peak overnight pricing can drop below $0.30. The spread between the two is what makes shifting usage so valuable.
SDG&E peak hours (San Diego)
SDG&E's default residential plan is TOU-DR1, with optional TOU-DR2 and EV-TOU-5 plans:
- TOU-DR1: on-peak is 4–9 p.m. every day. Weekends and holidays include a "super off-peak" window in the middle of the day.
- EV-TOU-5: a flat monthly fee plus very cheap midnight–6 a.m. pricing — designed for EV charging and home batteries.
SDG&E has some of the highest residential rates in the country. Summer peak pricing routinely exceeds $0.70 per kWh, while super off-peak can be under $0.25. A single evening of AC use can cost more than a full day of off-peak usage.
How solar + battery wins TOU
Solar alone helps, but a solar array peaks at midday — well before the 4–9 p.m. peak window. Without a battery, you're exporting cheap midday power to the grid and then buying expensive evening power back. Under NEM 3.0, export credits are a fraction of retail rates, which makes that trade especially bad.
A battery flips the math. Your panels charge the battery during the day, and the battery discharges during the 4–9 p.m. peak window. You avoid buying power at $0.55–$0.75 per kWh and instead use power you generated for free. That's the "TOU arbitrage" play, and it's the main reason batteries pay back faster in California than almost anywhere else in the country.
What this means for your quote
When I design a system, the rate plan you're on changes everything: panel count, battery size, and which financing option (buy, lease-to-own, or PPA) makes the most sense. The fastest way to get an accurate picture is to share your latest utility bill — it includes the 12-month usage graph and tells me your current TOU plan.