SCE Peak Hours and Window Film: How to Cut Your 4 to 9 pm Cooling Load
If you are on a Southern California Edison time-of-use plan, you have probably noticed that the most expensive electricity hits right when your house is hottest. Late afternoon sun pours through west-facing windows, the AC kicks on, and you pay peak prices to cool a room the sun just heated.
That overlap is the connection between SCE peak hours and window film. Blocking solar heat at the window means your AC has less work to do during the hours that cost the most. Here is how peak hours work, where film helps, and what else to do about it.
The short answer
On SCE's most common residential time-of-use plans, peak hours are 4 to 9 p.m. Window film does not change when peak hours happen, but it can reduce how much solar heat enters your home during them, so your air conditioner runs less when electricity costs the most. It helps most on sun-exposed, older single-pane windows, and least on newer low-e glass.
What are SCE's peak hours?
SCE offers several residential time-of-use (TOU) plans. In 2026, the main ones are:
TOU-D-4-9PM: peak hours are 4 to 9 p.m. This is SCE's common default plan.
TOU-D-5-8PM: a shorter 5 to 8 p.m. peak window with higher prices inside it.
TOU-D-PRIME: the same 4 to 9 p.m. window, for homes with an electric vehicle, battery, or heat pump.
How weekends and winter months are priced differs by plan, and prices change. Check your plan on your SCE bill or in your SCE account. Parts of south Orange County are served by SDG&E, whose main residential plans also use a 4 to 9 p.m. peak window, so confirm yours there too.
Why the timing matters
Peak electricity costs much more than off-peak electricity. EnergySage's 2026 summary of SCE's plans lists summer weekday peak prices from 58 to 74 cents per kilowatt-hour, up to about twice the off-peak rate.
Here is a simple illustration, not a quote. A typical central air conditioner draws roughly 3 kilowatts while running, though yours may differ. At 58 cents per kilowatt-hour, one hour of cooling costs about $1.74. At 34 cents, the same hour costs about $1.02. Over a five-hour peak window, that is about $8.70 versus $5.10. The less your AC runs between 4 and 9 p.m., the better.
SCE peak hours and window film: where film fits
West-facing windows receive their strongest direct sun in the afternoon, and that heat reaches the room just as the peak window begins. Residential air conditioning is a major contributor to California's peak electricity demand, and research from Lawrence Berkeley National Laboratory has shown that glazing which cuts solar heat gain can reduce cooling energy and peak cooling loads.
Window film works by rejecting solar heat at the glass. In U.S. Department of Energy modeling of window attachments, every option studied saved energy in cooling-dominated climates, because each one lowers solar heat gain. Film has one advantage over blinds and shades: it works during peak hours without anyone remembering to close it.
There are limits. The same Department of Energy modeling found that savings were largest on older single-pane windows and close to zero on newer double-pane low-e windows. If your home has low-e glass, film is more of a comfort, glare, and UV upgrade than a bill reducer. And film cannot change the price of electricity, only how much of it you need. For how film compares with other options, see Window Film vs Blinds, Shades, and Exterior Sun Screens.
A plan for peak hours
Window film works best as one piece of a plan:
Treat the worst windows first. West- and south-facing glass takes the afternoon sun. Start there.
Add shade where you can. Awnings and patio covers stop heat before it reaches the glass. See our guide to cooling a west-facing room.
Pre-cool before 4 p.m. Many utilities suggest cooling the home earlier in the day, then raising the thermostat during peak hours.
Close shades on west windows by early afternoon, before the sun reaches the glass.
Shift other loads. Run the dishwasher, laundry, and other big appliances before 4 p.m. or after 9 p.m.
Use fans in occupied rooms instead of leaving the AC running everywhere.
Check your plan. If most of your usage falls in the peak window, compare plans using your own usage.
Rebates and incentives
SCE and SDG&E have offered window film rebates for qualifying installations, with conditions such as single-pane glass. Terms change, so check eligibility before you rely on one. Our guide to choosing window film for energy savings in California covers the details.
Frequently asked questions
What are SCE peak hours?
On SCE's TOU-D-4-9PM and TOU-D-PRIME plans, 4 to 9 p.m. On TOU-D-5-8PM, 5 to 8 p.m. Check your own plan, since pricing for weekends and winter varies.
Does window film lower my electric bill on a time-of-use plan?
It can reduce how much your AC runs, including during peak hours, which can help your bill. The effect is largest on older single-pane windows and small on newer low-e windows.
Is window film worth it for cutting peak-hour AC use?
If you have sun-exposed, older single-pane windows, it is a strong candidate. If you have newer low-e glass, the energy savings are small, though film can still improve comfort, glare, and UV protection.
What else can I do to reduce AC use from 4 to 9 p.m.?
Pre-cool earlier in the day, close shades on west windows before the sun arrives, add exterior shade, shift appliance use, and use fans only in occupied rooms.
Want to know whether film makes sense for your home? Calview Films serves homes throughout Orange County. We check your glass and sun exposure and tell you honestly what to expect. Book a Free Assessment
Related guides: How to Cool a West-Facing Room | Heat & Glare Control Window Film | Window Film vs Replacing Windows
Sources: SCE, "Residential Rate Plan Comparison" (sce.com); EnergySage, "SCE Time-of-Use Rates: 2026 Peak Hours and Plan Costs"; U.S. Department of Energy and Lawrence Berkeley National Laboratory, "Energy Savings from Window Attachments" (2013); Lawrence Berkeley National Laboratory research on residential air conditioning peak demand and low solar gain glazing (ACEEE, 2004). Rates and plan details change, so confirm current figures with your utility.
