SRP's E-27 rate plan explained (and why customers call it a trap)

SRP’s E-27 Customer Generation Price Plan does two things at once. It sells you the cheapest electricity of any SRP residential plan, 6.13 cents a kilowatt-hour off-peak in July, and it charges you up to $36.05 for every kilowatt of on-peak demand above ten in the same month.

That combination is why the plan has a reputation. People shop it on the energy price, get billed on the demand charge, and find the two numbers have almost nothing to do with each other.

The tariff also carries an expiration date. SRP’s own price plan sheet says E-27 “will be eliminated as of the November 2029 billing cycle,” with anyone left on it moved to E-16.

Here is what the current tariff actually says, with the arithmetic worked out.

The short version

Every figure in this article comes from the E-27 Customer Generation Price Plan sheet (opens in a new tab), effective with the November 2025 billing cycle, including the transmission cost adjustment decrease effective January 2026. Retrieved August 9, 2026.

What E-27 actually is

E-27 is one of four SRP price plans for customers with rooftop solar. It sits in the “demand” family alongside the Average Demand Price Plan (E-15). The other two, Time-of-Use Export (E-13) and EV Export (E-14), have no demand charge and pay a flat 3.45 cents per exported kilowatt-hour instead.

The distinction matters more than the plan names suggest. SRP describes it plainly on its own site: the export plans credit each exported kilowatt-hour at a fixed rate, which “is different from net metering, used on the Customer Generation and Average Demand plans, in which the excess kWh is subtracted from the delivered kWh to arrive at a net kWh number.”

So E-27 really does net kilowatt-hours. The tariff’s Condition F is explicit:

The kWh delivered to SRP shall be subtracted from the kWh delivered from SRP for each billing cycle. If the kWh calculation is net positive for the billing cycle, SRP will bill the net kWh to the customer under this price plan. If the kWh calculation is net negative for the billing cycle, SRP will credit customer for the net kWh at the retail per-kWh price under this price plan.

Read the last clause again, because it is the whole trick.

The netting happens at this plan’s retail price, not at a normal retail price

“Net metering at retail” sounds like the old deal everyone remembers. On E-27 it is not, because the retail price on E-27 is deliberately the lowest SRP charges anyone.

• E-27 on-peak
• E-16 on-peak

View the numbers as a table

Energy price per kWh: E-27 against SRP's standard demand plan — full dataset

Category	E-27 on-peak (¢)	E-16 on-peak (¢)
Winter	6.73¢	11.19¢
Summer	6.62¢	12.57¢
Summer peak	8.23¢	16.54¢

Source: SRP E-27 and E-16 price plan sheets, effective November 2025 billing cycle. Excludes the temporary May to October 2026 reduction.

A kilowatt-hour you export in July and net against a July import is worth 6.13 or 8.23 cents. A neighbor on E-28 pays 12.76 cents for that same off-peak kilowatt-hour and 40.20 cents on-peak. Netting at retail is only generous if retail is high.

It is still better per exported kilowatt-hour than SRP’s 3.45 cent export credit. That is the honest comparison, and it is a narrower gap than the phrase “net metering” implies.

The demand charge is the plan

Three charges make up an E-27 bill: energy, demand, and the monthly service charge. For most solar households the demand charge is the largest of the three.

How it is measured

The tariff is one sentence: “The billing demand is the maximum thirty-minute integrated kW demand occurring during the on-peak periods of the billing cycle, as measured by the meter.”

One thirty-minute window. Not an average, not a count of how often you spike. The single worst half hour inside on-peak hours sets a charge that applies to the entire billing cycle.

When on-peak is

Under the November 2025 revision, which superseded the May 2019 version:

Six holidays are billed off-peak: New Year’s Day, Memorial Day, Independence Day, Labor Day, Thanksgiving and Christmas, each as observed. All other hours are off-peak.

Look at the winter windows. Neither 5 a.m. to 9 a.m. nor 5 p.m. to 9 p.m. contains meaningful solar production in December. From November through April, a solar array does essentially nothing to reduce the number your demand charge is calculated from.

What it costs

Demand charges are tiered. The first three kilowatts are cheapest, the next seven cost more, and everything above ten kilowatts costs the most.

Multiply that out and the shape of the plan becomes obvious.

• July and August
• November to April

View the numbers as a table

Total monthly E-27 demand charge, by peak on-peak demand — full dataset

Category	July and August	November to April
3 kW	36	15
5 kW	76	29
8 kW	136	50
10 kW	175	64
12 kW	248	86

Dollars per billing cycle. Calculated from the tiered per-kW charges in the SRP E-27 price plan sheet, effective November 2025.

Exact figures, since the chart rounds: 3 kW costs $35.70 in July, 5 kW costs $75.64, 8 kW costs $135.55, 10 kW costs $175.49, and 12 kW costs $247.59.

A 4-ton central air conditioner draws roughly 3 to 5 kilowatts on its own. Add a pool pump at 1 kW, an electric dryer at 2.8 kW, and a dishwasher, and a household can pass 10 kW without doing anything unusual. The difference between running those things sequentially and running them together, once, for half an hour, in July, is real money.

A worked example

Assumptions, labeled as illustrative rather than measured: a Tier 2 single-family home in a July billing cycle, 1,400 kWh delivered from SRP, 400 kWh delivered to SRP, so 1,000 kWh net. Of that net, 250 kWh falls in on-peak hours and 750 kWh off-peak. Peak 30-minute on-peak demand is 6 kW.

Energy, on-peak      250 kWh x $0.0823 =  $20.58
Energy, off-peak     750 kWh x $0.0613 =  $45.98
Demand      3 kW x $11.90 + 3 x $19.97 =  $95.61
Monthly service charge, Tier 2         =  $30.00
                                 Total = $192.17

The demand charge is 50 percent of that bill, and it was set by thirty minutes out of a 31-day month.

Now change one input. Shift enough load that peak on-peak demand lands at 4 kW instead of 6 kW, and the demand charge falls to $55.67. That is $39.94 saved in a single month without using one kilowatt-hour less. Let it run to 10 kW and the demand charge climbs to $175.49, adding $79.88.

Two notes on the example. SRP applies a temporary reduction of $0.0038 per kWh during the May through October 2026 billing cycles, which would trim about $3.80 off the energy portion above. And the minimum bill on E-27 is the monthly service charge, so a month where netting goes deeply negative still costs you $20 to $40.

Which SRP plan is the best?

There is no single answer, and any page that gives you one is guessing about your house. What the tariffs support is a fairly clean sorting rule.

The honest version of the E-27 question is not “is this plan good.” It is “can I hold my worst on-peak half hour under about 5 kW, every weekday, for two months a year.” If the answer is no, the lowest energy price in Arizona will not save you.

Is the SRP time-of-use plan worth it?

Depends which one, and the plan names changed in November 2025.

SRP’s old Time-of-Use Price Plan is discontinued. It is closed to new enrollment and ends after the November 2029 billing cycle, along with the EZ-3 plan, the Residential Demand pilot and the EV plan. SRP’s publicly elected board approved retiring those plans on February 27, 2025.

The current time-of-day plans for customers without solar are E-28, Conserve 6-9 p.m. and Save, and E-16, Manage Demand 5-10 p.m. and Save. E-28 has no demand charge and a summer peak on-peak price of 40.20 cents, more than three times its own off-peak price. E-16 has a demand charge and much flatter energy pricing.

For a solar household the comparison that matters is not E-27 against a time-of-use plan in the abstract. It is whether your bill is dominated by kilowatt-hours or by kilowatts. E-27 is a bet that it is kilowatts, and that you can control them.

Why customers call it a trap

Five things, and none of them is hidden. They are all in the tariff. They are just easy to miss.

The headline number is the wrong number. “Lowest energy price of any SRP residential plan” is true and mostly irrelevant if half your bill is a demand charge.

Solar does not reduce the measured quantity. In summer, on-peak runs to 8 p.m. Production has collapsed by 7 p.m. and the demand peak usually lands in that tail. In winter, on-peak is 5 a.m. to 9 a.m. and 5 p.m. to 9 p.m., and the array contributes nothing to either.

Netting at retail is netting at a low retail. Covered above. 6.13 cents in July, not the 12.76 cents an E-28 neighbor pays.

Leaving has a cost. Condition C of the tariff: a customer who cancels “may not subsequently elect service under this price plan for at least one year after the effective date of cancellation.” Testing another plan is not free if you want the option to come back.

The plan has an end date. November 2029. If your payback arithmetic runs past that, it is running on a tariff that will not exist, and E-16’s structure is materially different.

What changed in November 2025

The current E-27 sheet supersedes the May 2019 version, and the differences are not cosmetic.

• On-peak hours were redefined. Summer on-peak now runs 2 p.m. to 8 p.m.; winter now has two windows, 5 a.m. to 9 a.m. and 5 p.m. to 9 p.m.
• The monthly service charge moved to a three-tier structure, $20 for an apartment or condo unit at 0 to 225 amps, $30 for other dwellings at 0 to 225 amps, and $40 for any residence above 225 amps.
• Six observed holidays are billed off-peak.
• A transmission cost adjustment decrease took effect with the January 2026 billing cycle and is already folded into the figures above.
• A temporary reduction of $0.0038 per kWh applies to the May through October 2026 billing cycles, after which prices return to the posted levels with the November 2026 cycle.

If you are reading an E-27 explainer that lists a 1 p.m. to 8 p.m. summer window or a flat monthly service charge, it predates this revision.

What to check on your own bill

1. Find the demand line. Compare it against the energy line. If demand is the larger of the two, that is the number to manage, and using less total electricity will barely move it.
2. Find the time of your monthly peak. SRP’s account tools show when the 30-minute maximum occurred. Most households are surprised by the hour.
3. Count your Tier. A $40 monthly service charge means service above 225 amps, which is $240 a year more than Tier 1 before a single kilowatt-hour.
4. Check the date on any comparison you were shown. Anything modeled before November 2025 used different on-peak hours and different service charges.
5. Note 2029. If you are modelling a 15 or 20 year payback, four of those years are on E-27 and the rest are on something else.

Rates, hours and tariff language in this article were verified against the SRP E-27, E-16, E-13 and E-14 price plan sheets on August 9, 2026, all on the November 2025 billing cycle revision with the January 2026 transmission cost adjustment. SRP’s board adjusts price plans on its own schedule and is not regulated by the Arizona Corporation Commission. Confirm current figures against the linked tariff before deciding.

Related reading

• Is solar worth it in Arizona? puts demand charges into the wider payback picture, including why self-consumption beats export.
• Arizona net metering and net billing explains why SRP still nets kilowatt-hours while APS does not.
• Solar payback period in Arizona shows how much longer payback runs when avoided kilowatt-hours are worth 6 cents instead of 15.
• EV charging rate plans in Arizona covers the SRP EV plans that share E-27’s demand-plan lineage.
• APS solar buyback rates explained is the APS-side equivalent, where exports are paid a cash rate rather than netted.

• SRP
• Solar Basics
• Net Metering
• Arizona