Solar plus battery in Arizona: is it worth it?

Whether solar plus battery is worth it in Arizona is decided almost entirely by which utility serves your address and which rate plan you are on. The hardware is close to a commodity. The tariff is not.

On APS, the case rests on the gap between the 6.171 cent export rate and roughly 34 cents of on-peak retail energy. On SRP, it rests on a summer demand charge that reaches $36.05 per kW. Those are two completely different arguments, and a battery that makes sense under one may not under the other.

The short version

What changed, and why the question is live now

For years the grid functioned as a free battery. Solar exported at midday returned nearly full retail value, and power drawn back at night cost the same, so storing your own production had little upside.

That arrangement ended in Arizona in 2017. The Corporation Commission replaced retail net metering with an export-credit regime in Decision No. 75859, and APS export credits have fallen every year since under Rate Rider RCP.

View the numbers as a table

APS export rate by tranche, cents per kWh — full dataset

Year	Value (¢)
2017	12.9¢
2019	10.45¢
2021	9.405¢
2023	7.619¢
2025	6.171¢

Source: APS Rate Rider RCP tariff sheet, A.C.C. No. 6241. Tranche 2025 applies to interconnections Sep 1, 2025 through Aug 31, 2026.

The export rate is down 52 percent since 2017. Meanwhile on-peak retail energy on APS Rate Schedule TOU-E runs $0.34396 per kWh in summer.

That gap is the entire economic argument for storage on APS. A kilowatt-hour exported at midday earns 6.171 cents. The same kilowatt-hour stored and used at 6pm avoids about 34.4 cents. The spread is roughly 28 cents.

The full mechanics of the export rate, including the 10-year lock and the three ways to lose it, are in APS solar buyback rates explained.

The worked arithmetic on APS

Assumptions, all clearly illustrative rather than measured:

• A 13.5 kWh battery, cycled once daily, at 90 percent round-trip efficiency
• Usable throughput of about 12.15 kWh per cycle
• Displacing on-peak energy at $0.34396 rather than exporting at $0.06171
• 300 useful cycles per year, allowing for cloudy days and days when the house does not draw the full charge in the peak window

Value per kWh shifted: $0.34396 - $0.06171 = $0.28225
Per cycle:  12.15 kWh x $0.28225 = $3.43
Per year:   300 cycles x $3.43   = $1,029

Against an installed cost of $13,757 with no federal credit, that is a simple payback around 13.4 years.

Now change one assumption. The APS on-peak window is only three hours long, 4pm to 7pm on weekdays. A typical house does not draw 12.15 kWh in three hours unless it is running heavy air conditioning, and weekends are off-peak entirely. Cut the effective shifted energy to 8 kWh across 260 weekdays:

Per year: 260 x 8 kWh x $0.28225 = $587

Payback stretches past 23 years, which is longer than the battery warranty.

The honest reading: on APS, a battery bought purely on rate arbitrage is marginal at current prices. It gets meaningfully better if you value backup, if export rates keep falling at 10 percent a year, or if you can genuinely fill the peak window. It does not get better by wanting it to.

Does a battery help with SRP demand charges?

Yes, and this is where the strongest tariff case in Arizona sits. SRP’s E-27 plan bills on the single highest 30-minute on-peak demand in the billing cycle, reaching $36.05 per kW in July and August. A battery discharging through that half hour attacks the charge directly.

The tier structure on E-27, read from SRP’s own ratebook (opens in a new tab), is seasonal and the seasons are narrower than most summaries suggest:

• Summer Peak (Jul-Aug)
• Summer (May, Jun, Sep, Oct)

View the numbers as a table

SRP E-27 on-peak demand charge by tier and season — full dataset

Category	Summer Peak (Jul-Aug) ($/kW)	Summer (May, Jun, Sep, Oct) ($/kW)
First 3 kW	11.9$/kW	9.77$/kW
Next 7 kW	19.97$/kW	16.24$/kW
Additional kW	36.05$/kW	29.18$/kW

Source: SRP 2025 Ratebook E-27 with TCA. Winter (Nov-Apr) tops out at $11.00/kW.

Note the season definition carefully. “Summer Peak” is July and August only. An article that says “summer” and quotes $36.05 is wrong for four months of the year, when the top tier is $29.18. Winter, November through April, tops out at $11.00 per kW.

The arithmetic here is different in kind. A demand charge is set by one half-hour, so shaving 5 kW off a single August spike saves 5 x $36.05 = $180.25 in that month alone, before any energy savings. Two months of that is $360. The battery does not need to cycle daily to earn it; it needs to be available at the right half hour.

That is why storage is more attractive on an SRP demand plan than on a simpler APS energy-only plan.

Two further SRP facts worth knowing before committing:

• E-27 is being eliminated as of the November 2029 billing cycle. SRP’s tariff states that customers remaining on it will be moved to E-16. Any payback calculation that runs past 2029 on E-27 economics is calculating something that will not exist.
• E-27 does not pay an export rate at all. It nets exported kilowatt-hours against delivered kilowatt-hours at the plan’s retail price. The 3.45 cent export credit belongs to E-13 and E-14, which are different plans with no demand charge. Do not blend them.

What about the federal tax credit?

There is no federal tax credit for a homeowner who buys a battery outright in 2026. The residential clean energy credit under IRC Section 25D was repealed by Public Law 119-21, Section 70506.

This is the single most consequential change to battery economics in Arizona and it is frequently reported incorrectly, so the detail matters.

Section 25D(h) now reads that the credit “shall not apply with respect to any expenditures made after December 31, 2025.” Battery storage was covered under 25D(a)(6) as “qualified battery storage technology expenditures,” with 25D(d)(6) requiring capacity of not less than 3 kilowatt hours. All of it ends together.

One nuance on timing. The statute tests when expenditures are made, and Section 25D(e)(8)(A) treats an expenditure as made “when the original installation of the item is completed.” The IRS landing page phrases the cutoff as property “placed in service” after December 31, 2025. Those are not identical tests. The statute is the authority.

Section 48E remains available in 2026, and the new leasing restriction added by Public Law 119-21 Section 70513 applies only to solar water heating and small wind, not to solar electric or battery storage. So third-party-owned and leased systems can still access it. That credit belongs to the system owner, not to the homeowner. If you are buying, it does not reach you.

On the state side, the Arizona credit under A.R.S. 43-1083 (opens in a new tab) remains in force: 25 percent of cost, capped at $1,000 per residence cumulatively, with a five-year carryforward and no sunset clause in the statute. Whether a battery counts toward the device cost is indicated in the Form 310 instructions but could not be independently verified here, and standalone batteries with no solar are genuinely unclear under the statutory definition. Check Form 310 with azdor.gov directly before relying on it. The full incentive picture is in Arizona solar incentives and tax credits.

When a battery is worth it in Arizona

Three conditions, in descending order of how reliably they hold up.

You need outage backup. This is the one case that does not depend on arbitrage arithmetic at all. Arizona’s grid is most strained on the hottest summer evenings, which is exactly when losing air conditioning is most dangerous. If backup is the goal, the comparison is not against a cheaper solar-only system, it is against a generator. Nothing else on this list is as durable a reason. The grid strain picture is in Arizona grid peak demand explained.

You are on an SRP demand-charge plan. The half-hour mechanics above mean a battery targets the largest single line on the bill. Confirm your plan and confirm the season definitions.

Your export credit is low and your peak-window load is high. On APS this is the arbitrage case, and it depends on genuinely being able to fill the 4pm to 7pm window. Households with heavy late-afternoon air conditioning and electric vehicle charging get much closer to the favourable end of the arithmetic than households that are empty until 8pm.

When it does not pay

A battery is not automatic, and there are configurations where the numbers do not work.

If you are on an APS energy-only plan, do not need backup, and your household is not home during the on-peak window, the shifted energy volume is too small to carry a $13,757 cost over a reasonable term. The arithmetic above shows payback stretching past the warranty.

If you are on SRP E-27 and your payback horizon runs past 2029, the plan you are calculating against will no longer exist.

If you are being quoted a battery to make a marginal solar proposal look better, that is a reason to re-examine the solar proposal rather than to add storage. A clean solar-only system that pencils out on its own terms is a stronger position than one propped up by an appliance.

How long does a battery keep a home running in an outage?

It depends on the battery capacity and which circuits are backed up. A 13.5 kWh battery backing essentials, meaning lights, refrigeration, internet and one cooling zone, commonly runs 8 to 24 hours. Backing an entire house with central air in August can drain the same battery in a few hours.

Central air conditioning is the deciding variable. A 3-ton unit drawing roughly 3.5 kW while running will consume a 13.5 kWh battery in under four hours of continuous operation, and in Phoenix in August it runs close to continuously. Most households therefore back up a subset of circuits and accept partial cooling rather than attempt whole-home backup.

That trade-off is worth deciding explicitly rather than discovering during the outage.

What about a Tesla Powerwall?

A Powerwall is one of several capable home batteries. The economics above are set by your utility tariff and your load shape, not by the brand.

For price context, EnergySage marketplace data for the first half of 2026 shows meaningful spread: Tesla Powerwall 3 at 13.5 kWh around $967 per kWh, Enphase IQ Battery at 10 kWh around $1,429 per kWh, against an Arizona median of $1,019 per kWh. The full brand range across the marketplace ran from $342 to $3,505 per kWh, which is wide enough that comparing quotes on a dollars-per-usable-kWh basis is worth the effort.

Beyond price, the specifications that change the outcome are usable capacity as opposed to nameplate, continuous power output in kW (which determines what can run at once), round-trip efficiency, and the warranted throughput or cycle count.

Common questions

Is a battery worth it in Arizona?

It depends on your utility and whether you need backup. On an SRP demand-charge plan, where a single half-hour spike can cost $36.05 per kW in July and August, a battery targets the largest line on the bill and the case is strong. On an APS energy-only plan without backup needs, current arithmetic puts payback beyond 13 years and often beyond the warranty.

Backup is the most durable reason. It does not depend on rate arbitrage holding up over 15 years.

Does a battery help with SRP demand charges?

Yes, directly. SRP E-27 bills on the maximum 30-minute integrated on-peak demand in the billing cycle. Shaving 5 kW off a single August peak saves about $180 in that month at the $36.05 per kW top tier.

Two cautions. The $36.05 tier applies only to July and August billing cycles; May, June, September and October top out at $29.18, and winter at $11.00. And SRP’s tariff states E-27 will be eliminated as of the November 2029 billing cycle, with remaining customers moved to E-16.

Is there still a federal tax credit for home batteries?

Not for a homeowner buying outright. IRC Section 25D, which covered qualified battery storage at 3 kWh capacity and above, was repealed by Public Law 119-21 Section 70506 and does not apply to expenditures made after December 31, 2025.

Section 48E remains available to the owner of a third-party-owned or leased system, and the new leasing restriction does not extend to battery storage. That credit accrues to the leasing company, not to the homeowner.

How much does a home battery cost in Arizona?

EnergySage marketplace quote data for the first half of 2026 puts Arizona at about $1,019 per kWh, or roughly $13,757 for a 13.5 kWh system before incentives. The national average for the same capacity was around $15,647.

That is marketplace quote data rather than a regulated price or a benchmark study, and the brand spread was wide, from $342 to $3,505 per kWh. Compare quotes on dollars per usable kWh rather than on headline system price.

How long does a home battery last during an outage?

A 13.5 kWh battery backing essential circuits commonly runs 8 to 24 hours. Backing central air conditioning changes that completely: a 3-ton unit drawing roughly 3.5 kW will empty the same battery in under four hours of continuous operation.

Most Arizona households back up a subset of circuits and accept partial cooling. Deciding which circuits before rather than during an outage is the part that gets skipped.

Related reading

• APS solar buyback rates explained covers the export rate this entire calculation depends on.
• APS rate plans explained covers which plan you are on and what the on-peak window costs.
• Is solar worth it in Arizona? covers the underlying solar payback before storage is added.
• Arizona solar incentives and tax credits covers what remains after the federal credit ended.

Tariff, statute and cost figures were verified against APS and SRP tariff sheets, the US Code and market survey data on August 10, 2026. The worked examples use stated assumptions and are illustrative, not a projection for any specific home.

• Solar Basics
• SRP
• APS
• Arizona