California TOU Rates and Solar: How to Optimize Your System for Maximum Savings in 2026

Adrian Marin|Independent Solar Advisor, Temecula CA

Helping Riverside County homeowners navigate SCE rates and solar options since 2020

SCE charges 34-55 cents per kWh during the 4pm-9pm peak window. Your solar panels produce almost nothing after 4pm. That timing gap is the most important thing to understand about solar economics under NEM 3.0 - and there are specific strategies to close it.

What TOU Rates Are and Why They Matter for Solar

Time-of-use electricity rates charge different prices depending on when you use power. Southern California Edison divides each day into two or three rate tiers: on-peak (expensive), off-peak (moderate), and on some plans, super off-peak (cheapest). The specific hours and prices depend on which TOU plan you are enrolled in.

For standard households without solar, TOU rates create an incentive to shift dishwasher, laundry, and EV charging to overnight hours. For solar homeowners, TOU rates create a more complex optimization problem - because the hours when solar produces the most power are not the same hours when grid electricity is most expensive.

Under California's NEM 3.0 program (effective for all new solar customers who connected after April 14, 2023), the stakes are higher than they were under NEM 2.0. The grid no longer acts as a free battery. When you export solar to the grid during the day, SCE pays you approximately 5-8 cents per kWh under the Avoided Cost Calculator (ACC) rate. When you buy power back during the evening peak, you pay 34-55 cents per kWh. Understanding and optimizing around TOU rates is now the primary lever for maximizing solar ROI in SCE territory.

SCE Peak Hours and Rate Structure: The Numbers You Need

SCE's two main TOU rate plans for residential solar customers are TOU-D-PRIME and TOU-D-4-9PM. Both define the on-peak window as 4pm-9pm, seven days a week year-round. The rate amounts differ.

TOU-D-PRIME Rate Structure

TOU-D-PRIME has the widest rate spread of any SCE residential plan. That spread is what creates the most compelling battery arbitrage opportunity.

The super off-peak window from 8am-4pm on weekdays aligns almost perfectly with peak solar production hours. Under NEM 3.0, solar export during this window earns only the ACC rate (5-8 cents). But solar production used directly in the home during this window avoids purchasing power at 18 cents, which is better than the export rate. Direct self-consumption is always more valuable than exporting.

TOU-D-4-9PM Rate Structure

TOU-D-4-9PM uses the same peak window but compresses the rate spread. On-peak rates are lower than TOU-D-PRIME, but off-peak rates are also higher.

TOU-D-4-9PM has no super off-peak tier. The entire non-peak period is priced the same. For solar homeowners without a battery, this plan can be more forgiving because evening consumption after 9pm is charged at roughly the same rate as daytime hours - there is no dramatic penalty for forgetting to shift an appliance. For solar homeowners with a battery, TOU-D-PRIME's wider spread creates more arbitrage value.

The Solar Production Gap: Why Your Panels Miss the Peak

Solar panels in Temecula and Murrieta follow the sun. Production ramps up around 8-9am, peaks between 11am and 2pm, and falls off through the afternoon. On a summer day with a south-facing 10 kW system, you might produce:

• 8am - 10am: 2-4 kW production
• 10am - 2pm: 7-10 kW production (peak solar window)
• 2pm - 4pm: 4-7 kW production (declining)
• 4pm - 5pm: 1-3 kW production (tail end)
• 5pm - sunset: 0-1 kW production (minimal)
• After sunset: 0 production

The 4pm-9pm on-peak window begins just as solar is winding down. In summer, you might capture one hour of partial overlap between solar production and peak rates - roughly 4pm-5pm when panels still produce 1-3 kW. The remaining four hours of peak time (5pm-9pm) have no solar production at all.

Winter makes this worse. Shorter days mean panels may stop significant production by 3:30-4pm, leaving the entire 4pm-9pm window without solar coverage. Homes in Temecula consuming 3-5 kW during winter evenings for heating, lighting, and cooking are buying that power entirely from the grid at peak rates.

This structural mismatch is why solar alone does not solve the TOU problem. The technology that closes the gap is battery storage.

Why Batteries Are Critical for TOU Optimization Under NEM 3.0

Under NEM 2.0, a solar homeowner on TOU rates could export midday solar at nearly the retail rate. If retail was 28 cents and peak was 47 cents, you still received 28 cents credit for midday exports, and the time-shifting was built into the billing math automatically.

NEM 3.0 eliminates that automatic time-shifting. Midday solar exports now earn the ACC rate: 5-8 cents. There is no credit buildup that offsets evening peak charges on a near-dollar-for-dollar basis. Every kilowatt-hour you buy during the 4pm-9pm window costs you 34-47 cents that cannot be recovered by day's export credits.

A battery physically moves energy through time. It absorbs excess solar during the midday production window and dispatches that stored energy during the 4pm-9pm peak window. Instead of buying 4 kWh from the grid at 47 cents each ($1.88) for two evening hours, your battery covers that load from stored solar. That is $1.88 per two-hour period you do not pay - every day.

At 10 kWh of daily battery dispatch during peak hours (a reasonable figure for a 13.5 kWh Tesla Powerwall or equivalent), the daily savings from avoided peak purchases are $3.40-4.70 on TOU-D-PRIME summer rates. Over a year at an average of $3.50 per day: $1,277 in avoided grid charges.

Battery Charge and Discharge Scheduling Strategy

A well-configured battery should follow a charging and dispatch schedule that maximizes peak avoidance. The optimal schedule depends on your rate plan, but for TOU-D-PRIME the logic is straightforward.

Charging Strategy

Charge the battery primarily from solar production during the super off-peak or off-peak window (8am-4pm on TOU-D-PRIME). Do not charge from the grid during off-peak hours at 18-21 cents unless the battery management system cannot fill from solar alone. Grid charging at off-peak rates to arbitrage against peak rates does create savings (18 cents in versus 47 cents avoided), but is less efficient than solar charging at near-zero cost.

Set your battery to reserve 20-30% of capacity as a backup reserve if you are in an SCE High Fire Threat District zone. The reserved capacity stays available for PSPS events rather than being depleted by daily cycling.

Dispatch Strategy

Set the battery to begin discharging at 4pm and dispatch through the 9pm end of peak. Most battery management systems (Tesla app, Enphase App, SolarEdge Energy Hub) allow you to configure this schedule directly. The battery should deliver its full available capacity during the on-peak window before allowing any grid import.

After 9pm, the battery should switch to grid-import mode. Off-peak power at 18-21 cents is cheap enough that depleting battery reserves overnight is less efficient than buying from the grid. Reserve battery capacity for the next day's solar charging cycle.

During summer heat events when evening consumption spikes from air conditioning running into the night, a single 13.5 kWh battery may not cover the full 4pm-9pm load. In those cases, shift what appliances you can out of peak hours (see the next section) to reduce the load the battery must cover.

Smart Appliance Scheduling for TOU Optimization

Appliance scheduling is the TOU optimization strategy available to every solar homeowner, battery or no battery. The goal is to shift high-draw appliances into the solar production window (10am-3pm) or the overnight off-peak window (9pm-7am), and out of the 4pm-9pm peak.

Pool Pump

A pool pump running at 1-2 kW for 6-8 hours per day is one of the largest controllable loads in a Temecula home. Move the run schedule to 10am-4pm. The pump runs during solar production, the solar system covers the load directly, and you avoid paying peak-hour rates for a load that runs perfectly well at any hour. In summer, a midday run window is also the warmest time of day for the pool - an incidental benefit. Variable-speed pumps running at lower RPM for longer can extend the solar-window run time further.

EV Charging

An EV charging at Level 2 (7-11 kW) during the 4pm-9pm on-peak window at TOU-D-PRIME summer rates costs $0.47 per kWh. For a 40 kWh session, that is $18.80 in electricity. Scheduled overnight at the off-peak rate of $0.21 per kWh, the same 40 kWh costs $8.40 - a $10.40 saving per charge session. For a household charging 4 times per week, that is $2,163 in annual savings from one scheduling change.

All major EVs (Tesla, Rivian, Ford F-150 Lightning, Chevy Equinox EV, Hyundai Ioniq 6) include built-in scheduled charging. Set the charge start time to 11pm and end time to 6am. This uses the cheapest overnight electricity in the off-peak window and avoids loading the 4pm-9pm peak with EV charging. If you also have a battery, setting the EV to charge overnight preserves the battery capacity to cover household peak loads.

Dishwasher

A dishwasher uses 1.2-1.8 kWh per cycle, with the heating element drawing 1-1.5 kW during the dry cycle. Running at 7pm during peak hours costs 0.56-0.84 cents on TOU-D-PRIME. Running at 10am on a delay-start setting uses production-window solar. Most modern dishwashers have a delay-start function; set it to run after 10am each day.

Washer and Dryer

Electric dryers draw 4-6 kW per cycle. Running a dryer at 6pm in summer on TOU-D-PRIME costs $0.94-1.41 in electricity per cycle. Morning laundry during solar hours (10am-2pm) brings that cost near zero if solar production covers the load. If you cannot shift to mornings, the overnight off-peak window is also acceptable at $0.21 per kWh.

Water Heater

Heat pump water heaters (now required in new California construction) can be scheduled to heat during solar hours using their built-in timers. Set the heating window to 9am-3pm. A heat pump water heater draws 300-750 watts during operation, making it an ideal solar-absorption load. Conventional resistance water heaters draw 4-5 kW; scheduling their heating window to 9am-11am puts that draw squarely in the solar production peak.

NEM 3.0 Avoided Cost Calculator: Timing Your Exports

Under NEM 3.0, the price SCE pays for excess solar you export varies by time of day, day of week, and month - similar to how TOU rates vary on the consumption side. The Avoided Cost Calculator (ACC) rates are published by the California Public Utilities Commission and change annually.

In general, ACC export rates are highest during late afternoon and evening hours when grid demand peaks and lowest during midday when there is already abundant solar on the grid (the California "duck curve" effect). Summer weekday afternoons around 5pm-7pm tend to have ACC rates of 10-15 cents, higher than the midday 5-6 cent rate. Winter evenings can reach 15-25 cents per kWh in the ACC schedule.

For battery owners, this means the optimal export timing - if any energy should be exported rather than stored - is during late afternoon, not midday. If your battery is fully charged by 2pm on a productive solar day and solar continues producing excess, that excess exports to the grid. Under ACC rates, late-afternoon excess production earns more than the midday overage would have earned.

The practical implication: do not try to run your battery at half-charge expecting to maximize ACC export rates. Fill the battery to 100% (minus backup reserve) as early as possible during the solar window, then let any remaining production export. You cannot predict afternoon production with certainty; a full battery is the guaranteed value, and any export above that is a bonus.

Choosing the Right TOU Plan: A Guide for SCE Solar Customers

SCE offers several TOU rate plans. For residential solar customers under NEM 3.0, the most relevant are TOU-D-PRIME, TOU-D-4-9PM, and TOU-D-5-8PM. Here is how to think about each.

TOU-D-PRIME: Best for Solar Plus Battery

TOU-D-PRIME's wide spread between off-peak rates (18 cents) and on-peak rates (47 cents summer) creates the largest arbitrage opportunity for battery storage. If you have a battery that can fully cover your 4pm-9pm load, TOU-D-PRIME maximizes the value of that battery. The super off-peak window also aligns your EV charging and high-draw appliances with solar production hours, reinforcing the savings stack.

TOU-D-PRIME is the plan most solar installers in Riverside County recommend for NEM 3.0 customers adding battery storage.

TOU-D-4-9PM: More Forgiving Without a Battery

TOU-D-4-9PM has lower peak rates (37 cents summer) and higher off-peak rates (24 cents). The rate spread is smaller. For solar homeowners without a battery who cannot reliably shift all evening consumption, TOU-D-4-9PM reduces exposure to the worst-case scenario: heavy peak-hour consumption with no solar or storage to offset it.

If your household has unavoidable evening consumption - working parents who cook dinner at 6pm, children who are home and active in the evening - TOU-D-4-9PM provides more predictable bills than TOU-D-PRIME without a battery.

TOU-D-5-8PM: The Option Worth Modeling

TOU-D-5-8PM shifts the peak window to 5pm-8pm instead of 4pm-9pm. The shorter peak window and one-hour later start can benefit solar homeowners in summer when panels still produce meaningfully at 4pm. This plan is worth modeling if your usage data shows particularly high consumption between 8pm and 9pm (a load profile common in households with teenagers or late-evening cooking patterns) that would be reduced by a narrower peak window.

Real Bill Calculation: Temecula Homeowner on TOU-D-PRIME

Here is how a month's bill works for a representative Temecula household on TOU-D-PRIME with solar and battery in July (summer peak period).

Household profile:

• 2,200 sq ft home, Temecula 92592
• 10 kW south-facing solar array (installed under NEM 3.0)
• 13.5 kWh Tesla Powerwall 3
• Two adults, two teenagers, work-from-home schedule
• EV scheduled to charge 11pm-5am
• Pool pump: 10am-3pm
• Monthly consumption: 1,400 kWh (July, with AC running)

Energy flows:

• Solar production (July): 1,650 kWh
• Direct solar self-consumption during production hours: 450 kWh (free)
• Battery charged from solar: 300 kWh (10 kWh/day x 30 days)
• Battery discharged during 4pm-9pm peak: 280 kWh (accounting for round-trip efficiency)
• Solar export to grid (ACC rate): 900 kWh at avg 7 cents = $63 credit
• Grid import during peak (4pm-9pm), above battery coverage: 50 kWh at 47 cents = $23.50
• Grid import overnight for EV + remaining household (off-peak, 9pm-8am): 270 kWh at 21 cents = $56.70
• Baseline charge, delivery charges, SCE fixed costs: approximately $11/month

July bill estimate:

Without the battery, peak-hour imports would have been 330 kWh instead of 50 kWh ($155 vs $23.50), and the bill would have been roughly $140-160. The battery and appliance scheduling together reduced the bill by $110-130 in a single summer month.

How to Read Your TOU Export Credits on Your SCE Bill

SCE bills for NEM 3.0 customers show export credits in a separate line item. The bill will show total energy exported in kWh, the ACC rate applicable to each time period (which varies by hour and season), and the total credit amount.

Key things to look for on your monthly statement:

• Total NEM credits: this is the total dollar value of ACC credits for all solar you exported during the billing period. Under NEM 3.0, expect this to be significantly lower than it would have been under NEM 2.0 for the same production amount.
• On-peak vs off-peak export breakdown: some bills show how much of your export occurred during on-peak vs off-peak vs super off-peak hours. If most of your exports are happening at midday (super off-peak), there is more opportunity to capture that production in a battery instead.
• Annual true-up: NEM 3.0 customers reconcile on an annual billing cycle. Monthly bills show estimated charges; the annual true-up adjusts for the actual year of production and consumption. Large credit carryover from winter to summer often evaporates faster than expected; do not rely on built-up credits to cover summer peak consumption.
• Delivery charges and non-bypassable charges: NEM 3.0 export credits do not offset delivery charges, public purpose charges, or the fixed monthly charge. These costs exist regardless of solar production and set a floor on your monthly bill even if you export more than you consume.

If your monthly export credits are large relative to your import charges, that is a signal that more of your solar production could be captured with a battery instead of exported at 5-8 cent ACC rates. The calculator below can help estimate how much a battery would reduce exports and increase direct savings.

TOU-D-PRIME vs TOU-D-4-9PM: Head-to-Head for Solar Homeowners

If you are installing solar today under NEM 3.0 and adding a battery, start on TOU-D-PRIME from day one. If you are installing solar without a battery and plan to add one in the next 1-2 years, enrolling in TOU-D-4-9PM temporarily reduces your risk during the battery-less period, and you can switch to TOU-D-PRIME once storage is installed. SCE allows rate plan changes once per 12-month period.

Frequently Asked Questions

Rate figures referenced in this article are based on SCE residential TOU tariff schedules as published in 2025-2026. Exact rates vary based on billing tier, baseline allowance, and rate schedule elections. Verify current rates at sce.com before making purchasing decisions. NEM 3.0 ACC export values are illustrative averages based on CPUC Avoided Cost Calculator outputs and vary by hour, day, and season.