If you run AC in San Diego summers, the cheapest SDG&E plan is a time-of-use plan like TOU-DR1, paired with a smart thermostat that pre-cools your home before the 4-9pm peak. The plan itself matters less than the move: cool the house on cheap power before 4pm, then coast through the expensive window with the AC barely running. That single habit beats any plan you pick if you ignore the clock.
Here’s the trap most San Diego homeowners fall into. They hear AC is expensive, so they crank it hardest from 4pm to 9pm when they get home and it’s hottest. That’s the most expensive electricity of the day. The fix isn’t a new AC or solar panels. It’s timing, and a thermostat that handles the timing for you.
How SDG&E time-of-use pricing works
SDG&E charges most homes by when you use power, not just how much. There are three pricing windows on the common plans, and the difference between them is huge in summer.
On nearly every SDG&E residential plan, the on-peak window is the same: 4pm to 9pm, every day. That’s when power costs the most. Super off-peak is the cheapest, and starting May 2026, SDG&E added a weekday super off-peak block from 10am to 2pm on top of the overnight midnight-to-6am window. Off-peak fills in the rest. You can confirm the current windows on the SDG&E pricing plans page.
The gap between cheap and expensive power is what makes timing pay. On TOU-DR1, the official rate table shows summer on-peak running far above super off-peak, a difference of roughly 30 cents per kilowatt-hour between the two (Schedule TOU-DR1 total rates). Rates change a few times a year, so treat any number you read as a snapshot and check the current rate sheet before you decide.
SDG&E rate plans compared for AC users
Here’s how the main residential plans stack up if your goal is running AC in summer without a giant bill.
| Plan | On-peak window | Best for | AC strategy |
|---|---|---|---|
| TOU-DR1 | 4pm-9pm daily | Most homes that can shift AC use | Pre-cool 10am-2pm and before 4pm, ease off 4-9pm |
| TOU-DR2 | 4pm-9pm daily | Homes with steady evening use, no midday flexibility | Fewer cheap windows, so the 4-9pm setback matters even more |
| TOU-DR-P | 4pm-9pm daily | Homes that can cut hard on event days | Same pre-cool habit, plus deep setbacks on Reduce Your Use events |
| Standard DR (tiered) | None (flat by usage) | Low total users who can’t shift timing | Run AC anytime, but watch total kWh and tier 2 pricing |
| EV-TOU-5 | 4pm-9pm daily | Homes with an EV (and ideally a battery) | Charge car and pre-cool overnight, coast 4-9pm |
A few notes on each.
TOU-DR1 is SDG&E’s default time-of-use plan and the sweet spot for most AC households. Three pricing windows means more cheap hours to pre-cool in. With the new 10am-2pm super off-peak block, you can chill the house mid-afternoon on the cheapest power, then ride it out through peak.
TOU-DR2 is the simpler two-window version: on-peak and off-peak only, no super off-peak. After the May 2026 changes, it lost the cheap midday block that the three-window plans now get, so it’s harder to recommend for a home trying to time its AC (Stellar Solar’s 2026 rate breakdown).
TOU-DR-P is TOU-DR1 with a twist: on a handful of “Reduce Your Use” event days, the 4-9pm price spikes with a large per-kWh adder, but you get bill credits for cutting back. If your thermostat already pre-cools and backs off at 4pm, you’re set up to win on event days. If you can’t reliably cut use, skip it.
Standard DR is the old-school tiered plan with no time-of-use at all. You pay by how much you use, and the price jumps once you pass your baseline allowance (SDG&E pricing plans). It can work for a small home with low total usage that genuinely can’t shift timing. For most AC users running a 3-ton system through a heat wave, the tier 2 pricing adds up fast.
EV-TOU-5 is built for homes with an electric vehicle. It has the widest gap between cheap and expensive power of any residential plan, which makes overnight charging cheap and 4-9pm use very pricey (SDG&E EV plans). If you have an EV, it’s usually the right home for your AC too, because the same overnight-and-midday pre-cooling habit applies. Without an EV, it’s not the plan for you.
The pre-cooling tactic that actually saves money
This is where the HVAC side does the heavy lifting that solar companies won’t tell you about. You don’t need panels to beat the peak. You need a schedule.
Pre-cooling means running your AC before the 4pm peak so your house is already cool when the expensive window starts. A well-sealed San Diego home holds that cool air for hours. From 4pm to 9pm, your AC barely cycles because the work is already done.
Here’s a simple summer schedule for a TOU-DR1 home:
- 10am to 2pm: Let the AC run and cool the house a degree or two below your target. This is super off-peak power now, the cheapest of the day.
- 2pm to 4pm: Hold steady on off-peak.
- 4pm to 9pm: Set the thermostat up by 3 to 4 degrees. The house drifts up slowly from the cool you banked. The AC stays mostly off during the most expensive hours.
- 9pm onward: Back to normal as rates drop again.
The catch is doing this every day without thinking about it. That’s the whole point of a smart thermostat installation. A Nest, Ecobee, or Honeywell unit runs this schedule automatically and adjusts for the weather. You set it once and forget it.
ENERGY STAR data shows smart thermostats save 8 to 12% on heating and cooling on their own. On a time-of-use plan, the pre-cool habit can add another 10 to 15% on top, because you’re moving the work into cheap hours. For a typical San Diego home, that stacks into real money over a summer.
Why this matters more inland
San Diego’s coast and its inland valleys live in different climates. A home in Escondido or Santee runs AC far harder and longer than a home near the water. More AC hours means more exposure to that 4-9pm peak, which means the pre-cooling habit saves more.
Inland homes also tend to have the AC load that pushes a tiered Standard DR plan into expensive tier 2 territory. A time-of-use plan plus pre-cooling gives those homes a way to run the AC they actually need without paying peak rates for it.
One more piece. Pre-cooling only works if your system is efficient enough to bank cool air fast and hold it. A dirty coil, low refrigerant, or a clogged filter means your AC works harder and cools slower, which kills the strategy. Annual AC maintenance keeps the system tight enough that pre-cooling actually pays off.
Should you switch plans?
Start by logging into your SDG&E account and looking at the Plan Chooser, which compares your past usage across plans using your real data. That’s more accurate than any rule of thumb, because it knows your actual hours. SDG&E also lets you switch plans without a fee, so there’s low risk in trying TOU-DR1 for a summer if you’re on the old tiered plan.
The honest answer for most San Diego AC households: get on a three-window time-of-use plan, install a smart thermostat that pre-cools, and keep the system maintained. That combination beats chasing the perfect plan name. The plan sets the prices. The thermostat decides when you pay them.
When to call us
If you want help setting up a pre-cool schedule, or you’re not sure your AC can hold cool air through a peak window, that’s an efficiency check worth doing before the next heat wave. Climate Pros SD connects you with vetted local HVAC pros who handle smart thermostat installs and tune-ups across San Diego County.
Call (442) 777-6440 for a smart thermostat install or a summer efficiency check.
FAQs
What is the cheapest SDG&E plan if I run my AC a lot?
For most homes that run AC heavily, a three-window time-of-use plan like TOU-DR1 is cheapest, but only if you shift cooling out of the 4-9pm peak. The plan gives you cheap super off-peak hours overnight and from 10am to 2pm to pre-cool. If you run AC hard from 4pm to 9pm without shifting, even a good plan gets expensive. Use the SDG&E Plan Chooser with your real usage to confirm.
When is SDG&E’s peak rate?
On nearly every SDG&E residential plan, on-peak is 4pm to 9pm, every day, including weekends. That’s the most expensive power of the day. Super off-peak is the cheapest, overnight from midnight to 6am, plus a weekday 10am-to-2pm block added in May 2026. Confirm the current windows at sdge.com, since they can change.
Can a smart thermostat save me money on TOU rates?
Yes, and it’s the single biggest lever. A smart thermostat automates pre-cooling, running the AC on cheap power before 4pm so the house coasts through the expensive peak. ENERGY STAR puts smart thermostat savings at 8 to 12% on its own, and time-of-use optimization can add another 10 to 15%. The value is that it runs the schedule every day without you touching it.
Is EV-TOU-5 worth it just for air conditioning?
Only if you also have an electric vehicle. EV-TOU-5 has the widest gap between cheap and expensive power of any SDG&E residential plan, which rewards overnight EV charging and the same overnight pre-cooling habit. Without an EV, the plan isn’t built for you, and a standard time-of-use plan like TOU-DR1 is the better fit for AC alone.
Do I have to change plans to save on AC?
No. The biggest savings come from when you cool, not which plan you’re on. If you’re already on a time-of-use plan, just add the pre-cool habit with a smart thermostat. If you’re on the old tiered Standard DR plan, switching to a three-window plan plus pre-cooling usually saves more. SDG&E lets you switch plans without a fee, so the downside is low.