Is E-23 or E-28 cheaper?

E-23 and E-28 cost about the same for a typical Arizona home (within $2 a year). E-28 stays cheaper at every level of use from 200 to 2,500 kWh a month with the same daily pattern of use. Adding an EV driven 1,000 miles a month and charged at each plan’s cheapest hour, E-28 gives the lower total ($168 against $188 a month).

What is the difference between E-23 and E-28?

E-23 is flat: the same price at every hour, with a fixed charge of $30.00 a month. E-28 is time-of-use (summer weekdays: Mid-peak 12 am–8 am, Mid-peak 3 pm–6 pm, Peak 6 pm–9 pm, Mid-peak 9 pm–12 am; lowest price 8 am–3 pm), with a fixed charge of $30.00 a month.

HomeWattCost

SRP E-23 vs E-28

E-23 and E-28 cost about the same for a typical Arizona home (within $2 a year). E-28 stays cheaper at every level of use from 200 to 2,500 kWh a month with the same daily pattern of use.

Utility SRPTariffs checked 2026-09-28Typical use 1,052 kWh/mo, Arizona

Head to head

Scenario	E-23	E-28	Cheaper
Typical home, per month	$156	$155	Tie
All-in price per kWh	14.8¢	14.8¢	E-28
Home + EV, charged at the cheapest hour	$188	$168	E-28
Home + EV, plugged in at 6 pm	$188	$206	E-23
Fixed charge	$30.00	$30.00

Typical home: Arizona average use by month (EIA), shaped hour by hour (NREL ResStock), before taxes. EV: Tesla Model Y Long Range AWD, 1,000 miles a month; cheapest start any hour on E-23, 8 am on E-28.

Month by month

Typical-home bill each month on each plan.

Plan	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
E-23	$113	$100	$124	$120	$153	$198	$263	$266	$183	$132	$106	$109
E-28	$111	$99	$123	$119	$153	$199	$265	$269	$182	$131	$105	$108

E-23: price by hour

July weekday.

Same price all day

E-28: price by hour

July weekday.

Off-peakMid-peakPeak

How the two plans work

E-23: Basic Price Plan

One price per kWh at every hour: 13.6¢ in July and 11.0¢ in January.
Shifting use to other hours changes nothing on this plan; using less is the only lever.
Fixed charge: $30.00 a month.

E-28: Conserve 6-9 p.m. and Save

Mid-peak 12 am–8 am, Mid-peak 3 pm–6 pm, Peak 6 pm–9 pm, Mid-peak 9 pm–12 am on July weekdays; 3 of 24 hours carry the top price of 39.8¢.
The cheapest July weekday hour costs 6.2¢, so moving 1 kWh out of the top hours saves 33.6¢.
January weekdays range from 4.3¢ to 15.1¢.
Weekends follow a different schedule from weekdays.
Fixed charge: $30.00 a month.

Your own pattern of use decides the winner: compare every SRP plan on your usage, or see all SRP plans, sources and peak hours.