EV charging rate plans in Arizona: APS vs SRP compared

If you drive an electric car in Arizona, which utility serves your house now changes your charging bill more than which car you bought.

APS still offers a dedicated EV rate plan. R-EV prices power at 8.468 cents a kilowatt-hour between 11 p.m. and 5 a.m. on weeknights, about 31 percent below its own standard off-peak rate.

SRP no longer offers one to new customers. The SRP Electric Vehicle Price Plan, tariff code E-29, was closed to new enrollment with the November 2025 billing cycle and will be eliminated after November 2029. SRP’s publicly elected board approved retiring it, along with three other residential plans, on February 27, 2025.

What replaced it is not another overnight plan. SRP’s remaining residential plans put their cheapest window from 8 a.m. to 3 p.m., which is exactly when most people’s cars are not at home.

The short version

Does APS have an EV rate plan?

Yes. R-EV, marketed as EV Overnight Charging 11pm-5am, is open to new customers and prices power at 8.468 cents per kWh between 11 p.m. and 5 a.m. on weeknights. That is about 31 percent below the standard off-peak rate. The plan requires annual proof that you own an electric vehicle.

R-EV is one of four APS residential plans open to new customers. The tariff requires “an annual certification for proof of EV ownership.”

It is a standard time-of-use plan with a fourth pricing window bolted on. Rates below are from the APS tariff sheets, all on the March 8, 2024 revision under Commission Decision No. 79293, via APS rates, schedules and adjustors (opens in a new tab). Summer is the May through October billing cycles; winter is November through April.

Two details do most of the work here.

The overnight window is weekdays only

Saturday and Sunday charging bills at off-peak, at 12.345 cents. If you do most of your charging at the weekend, R-EV gives you nothing.

You pay for the overnight discount with a higher on-peak rate

R-EV’s on-peak price is about 7 percent above the plain time-of-use plan, TOU-E, which charges 34.396 cents in summer. Fourteen holidays are billed at off-peak on all APS time-of-use plans.

Where R-EV breaks even

The break-even is easy to state. Overnight power saves 3.877 cents a kilowatt-hour against off-peak. On-peak power costs 2.428 cents a kilowatt-hour more than it would on TOU-E. Charging 300 kWh a month overnight saves about $11.63, which covers an on-peak penalty on roughly 480 kWh of 4-to-7-p.m. weekday consumption. Very few households come close to 480 kWh in that window, so if you genuinely charge overnight on weeknights, R-EV wins.

Does SRP have an EV rate plan?

Not for new customers. SRP closed its Electric Vehicle Price Plan, tariff code E-29, to new enrollment with the November 2025 billing cycle, and the plan ends entirely after November 2029. Customers already on it keep it until then. Everyone else chooses from four plans, none of them EV-specific.

E-29 was a good plan. It is simply no longer on offer.

What E-29 still costs for customers on it

For customers still on it, the current prices are below. Summer is May, June, September and October; summer peak is July and August; winter is November through April.

Winter on-peak is 5 a.m. to 9 a.m. and 5 p.m. to 9 p.m. Summer on-peak is 2 p.m. to 8 p.m. The monthly service charge is $20, $30 or $40 depending on dwelling type and service amperage.

SRP will notify remaining E-29 customers at least 120 days before the plan ends.

What SRP offers a new EV owner instead

Four plans, none of them EV-specific.

Both tariffs are explicit that super off-peak runs “from 8 a.m. to 3 p.m., Mountain Standard Time, on weekdays and weekends, including holidays. All hours that are not on-peak or super off-peak are off-peak.”

Read that carefully. On SRP, 11 p.m. to 5 a.m. is ordinary off-peak. There is no overnight discount for new customers at all.

How much does it cost to charge an EV in Arizona?

Between $25.40 and $40.65 a month for 300 kWh charged overnight, depending on your utility and plan. APS R-EV is the cheapest at $25.40. SRP’s Conserve 6-9 p.m. plan in winter is the most expensive at $40.65. That is $183 a year apart for the same electricity at the same hour.

Assume 300 kWh a month of charging, which at roughly 3.3 miles per kilowatt-hour is about 990 miles. All of it done overnight, between 11 p.m. and 5 a.m., which is what most people with a home charger and a timer actually do.

• July and August
• November to April

View the numbers as a table

Monthly cost of 300 kWh charged overnight, by plan — full dataset

Category	July and August	November to April
APS R-EV	25.4	25.4
APS TOU-E	37.04	37.05
SRP E-16	29.88	29.82
SRP E-28	38.28	40.65

Dollars per month. Calculated from APS tariff sheets (March 8, 2024 revision) and SRP E-16 and E-28 price plan sheets (November 2025 billing cycle). APS does not distinguish a July-August season.

APS’s dedicated plan is the cheapest overnight option available to a new customer on either system, at $25.40 a month. The most expensive is SRP’s Conserve 6-9 p.m. plan in winter, at $40.65, a difference of $183 a year for the same electricity at the same hour.

Two caveats on the chart. It counts energy charges only, so APS’s $0.458 daily service charge and SRP’s $20 to $40 monthly service charge are excluded, as is the demand charge on E-16. And it assumes every kilowatt-hour lands inside the stated window, which a timer makes realistic but a plugged-in-at-6-p.m. habit does not.

When is the cheapest time to charge an EV in Arizona?

It depends entirely on your utility, and the two now point in opposite directions. On APS, the cheapest hours are 11 p.m. to 5 a.m. on weeknights. On SRP, they are 8 a.m. to 3 p.m., every day of the year. The cheap window moved from midnight to noon, and it is not obvious from any plan name.

• Overnight, 11 p.m. to 5 a.m.
• Midday, 8 a.m. to 3 p.m.

View the numbers as a table

Price per kWh in July and August: overnight against midday — full dataset

Category	Overnight, 11 p.m. to 5 a.m. (¢)	Midday, 8 a.m. to 3 p.m. (¢)
APS R-EV	8.47¢	12.35¢
SRP E-16	9.96¢	6.22¢
SRP E-28	12.76¢	6.61¢

Sources: APS R-EV tariff sheet (March 8, 2024 revision) and SRP E-16 and E-28 price plan sheets (November 2025 billing cycle). APS has no summer super off-peak window, so its midday figure is the off-peak rate.

The two systems now point in opposite directions. On APS, overnight is cheap and summer midday is not, because APS’s super off-peak window only exists from November through April. On SRP, midday is cheap year-round and overnight is merely ordinary.

The reason is grid shape rather than marketing. Both utilities have more solar on their systems than they used to, which makes midday power abundant and evening power scarce. APS has priced that into a winter-only window. SRP has priced it into every day of the year and dropped its overnight discount entirely.

The practical consequence for an SRP driver: if you can charge between 8 a.m. and 3 p.m., you pay 6.22 cents in July on E-16 and 3.93 cents in May or October. That is cheaper than anything APS sells a driver in summer. If you cannot, because the car is at an office all day, you pay ordinary off-peak and SRP has nothing better to offer you.

If you have solar and an EV

SRP has one EV-specific plan left, and it requires on-site generation. E-14, the Electric Vehicle Export Price Plan, keeps an 11 p.m. to 5 a.m. super off-peak window and applies it on weekends as well as weekdays.

E-14 carries no demand charge. Exported solar is credited at a flat 3.45 cents per kilowatt-hour for “the total kWh delivered to SRP during that billing cycle.” Like E-27 and E-13, it is eliminated as of the November 2029 billing cycle, with remaining customers moved to E-28.

On the APS side there is no solar-specific EV plan. Solar customers choose between TOU-E and R-3, and R-EV is not listed among the plans available to distributed generation customers. An APS household with both solar and an EV therefore has to pick which asset to optimize the rate plan around.

Is APS or SRP cheaper for EV charging?

Neither, in general. It turns on when the car is plugged in. Charge overnight on weeknights and APS R-EV is the cheapest option on either system. Charge in the middle of the day and SRP’s 8 a.m. to 3 p.m. super off-peak beats everything APS sells in summer. Three profiles, three different answers.

You charge overnight on weeknights and have no solar

APS R-EV is the cheapest option available to a new customer on either system. On SRP, choose between E-16 and E-28 on your evening usage, not your charging.

You are home during the day, or your car is

SRP’s midday super off-peak beats everything APS offers in summer, at 3.93 to 6.61 cents. On APS, the winter super off-peak window at 3.495 cents is the cheapest residential power in this article, but it only runs November through April.

You have rooftop solar

Charge from your own production. On APS, a self-consumed kilowatt-hour is worth 15.418 cents against an export credit of 6.171 cents. On SRP’s export plans, it is worth the retail price against a 3.45 cent credit. Every kilowatt-hour you move from export into the car is worth the difference, and it is the largest single lever in this article.

The fine print worth checking

1. Weekends. APS R-EV’s overnight window is weekdays only. SRP E-14’s runs every day. This alone can decide the plan.
2. Holidays. APS bills 14 holidays at off-peak. SRP recognizes six, and on E-16 and E-28 the midday super off-peak window applies on holidays too.
3. EV certification. R-EV requires annual proof of ownership. Sell the car and the plan eligibility goes with it.
4. Demand charges. E-16 has one. An EV charger drawing 7 to 11 kW at 6 p.m. on that plan is an expensive mistake; the same charger at midnight is not, because on-peak on E-16 ends at 10 p.m.
5. The 2029 dates. E-29 and E-14 both end after the November 2029 billing cycle. If you are modelling charging costs over a longer horizon than that, the second half of your model is on a different tariff.
6. Adjustors and service charges. Every figure above is a base energy price. APS adjustors and SRP’s fuel and purchased power adjustment apply on top, and SRP is running a temporary reduction of $0.0038 per kWh during the May through October 2026 billing cycles.

Rates, windows and tariff language in this article were verified against published APS tariff sheets and the SRP E-29, E-16, E-28 and E-14 price plan sheets on August 9, 2026. APS tariffs are on the March 8, 2024 revision; SRP plans are on the November 2025 billing cycle revision. Confirm current figures against the linked tariffs before switching plans.

Related reading

• APS rate plans explained covers all four open APS residential plans and the demand-charge crossover.
• SRP’s E-27 rate plan explained covers the demand-plan structure that E-16 shares.
• Is solar worth it in Arizona? explains why charging from your own production beats exporting it.
• Arizona net metering and net billing covers the 3.45 cent SRP export credit referenced above.
• Solar payback period in Arizona shows what adding EV load does to the self-consumption share that drives payback.

• APS
• SRP
• Arizona