Sources

Every number on this site comes from one of the documents below. Figures are dated where the source is dated; savings figures are modeled projections from the APS tariffs listed here.

Rates and export credits

  • APS Resource Comparison Proxy schedule, 5.554 cents per kWh from September 1, 2026 (ACC Decision 82122)
  • APS TOU-E and R-3 tariffs: summer on-peak 34.396 cents, R-3 off-peak 5.943 cents and demand charge $19.585 per kW
  • ACC Decision 76295 (2017 rate case) and the rooftop export credit schedule since 2017
  • ACC docket E-01345A-25-0105: APS 2025 rate application, procedural order of July 10, 2026
  • Arizona Court of Appeals ruling of June 16, 2026 on the solar grid access charge (KJZZ, Arizona Attorney General)

Grid demand and reliability

  • APS peak demand of 9,164 MW on August 2, 2026 (KJZZ, August 5, 2026; APS)
  • APS Integrated Resource Plan: 8.7 GW of peak load today, 12 GW by 2035, about 19 GW of data center requests in queue
  • NERC 2025 Long Term Reliability Assessment: U.S. peak demand up 24 percent in ten years
  • U.S. Department of Energy CESER: 18 emergency grid orders since June 2026
  • EIA, December 2025: average U.S. outage hours in 2024
  • Wood Mackenzie via POWER, January 2026: large transformer lead times

Data centers

  • KJZZ, September 2, 2026: APS has not signed a new data center since 2024
  • ACC, April 2026: 10,600 MW of data centers planned in Arizona
  • Arizona Mirror, azfamily and KTAR, August 31, 2026: Attorney General call for a statewide pause
  • AZBEX and ABC15, September 1 to 2, 2026: Glendale data center with on site gas generation

Heat and outages

  • FOX 10 Phoenix, August 10, 2026: 42 poles down, about 22,000 West Valley homes without power
  • Maricopa County Public Health: 113 confirmed heat deaths by August 25, 2026; 72 percent of 2025 indoor deaths had a non functioning A/C

Price history and projections

  • EIA State Energy Data System, Arizona residential electricity prices 2010 to 2024; EIA Electric Power Monthly Table 5.6.A, 2025 to 2026
  • EIA Table 5A, 2024: Arizona average residential bill $160.24 at 1,075 kWh
  • APS TOU-E tariff (Decision 79293) and APS bill adjustors page, September 2026: PSA 1.698, TCA 0.536, REAC 0.621, LFCR 0.246, CRS 0.148, DSMAC 0.075 cents per kWh
  • Pinnacle West 10-K filings 2017 to 2025: Power Supply Adjustor history; ACC news releases Aug 16 2017, Feb 23 2024, Feb 6 2025, Aug 6 2025
  • ABC15, Dec 19 2023: adjustors added 8.7 percent to 2023 bills; Arizona Attorney General intervention, Sep 15 2025
  • All-in price method: 1,000 kWh summer month on TOU-E, 25 percent on-peak, plus adjustors, basic service charge and about 5 percent tax; projection paces of 3.0, 4.7, 6.0 and 7.5 percent a year are illustrations tied to the records above, not forecasts

Nuclear and new supply

  • APS newsroom, Feb 5 2025: APS, SRP and TEP explore new nuclear; operation early 2040s
  • Pinnacle West and SRP, Jun 24 2026: DOE grant not awarded; self-funded six-month siting study; NRC early site permit decision about 2030
  • Arizona Capitol Times, Feb 25 2026: $5 to 10 billion per project; Axios Phoenix, Feb 11 2025: ratepayers expected to carry costs
  • APS newsroom: Redhawk expansion (2027), Cholla gas conversion (2029), Desert Sun (2030); Utility Dive, Nov 11 2024: APS peak demand up 40 percent by 2031

Financing

  • Palmetto LightReach Energy Backup program terms and Enerflo knowledge base, 2026; Energy-Storage.news, Jul 20 2026; Solar Power World, Jul 9 2026
  • Solar Topps Easy Ownership lease-to-own program, Phoenix, Sep 2026
  • Solar.com, Jun 15 2026 and pv magazine, Apr 15 2026: prepaid lease mechanics and 20 to 30 percent discount
  • EnergySage Arizona storage cost data, Sep 2026; Solar Topps Powerwall 3 pricing, Jun 2026; Sungage, GoodLeap and Dividend 2026 rate sheets
  • One Big Beautiful Bill Act, Section 48E storage credit and FEOC rules (Kirkland and Ellis, Aug 2025); IRS Notice 2026-15
  • A.R.S. 43-1083 (residential solar energy credit, 25 percent up to $1,000 per residence), 42-5001 and 44-1761 (definitions including storage), 42-5061 (sales tax exemption) and 42-11054 (property tax); Arizona Department of Revenue Form 310 instructions
  • APS Qualified Technology Installers (aps.com, Find Qualified Installers) and SRP Preferred Solar Installer Program (srpnet.com), checked Sep 17 2026

Batteries and incentives

  • Savings model assumptions: 8 kW array, 2,000 kWh July usage with about 264 kWh on-peak, about 1,300 kWh production, 715 kWh exported at the locked rate, 13.5 kWh battery cycled daily at 89 percent round-trip efficiency, on-peak grid draw capped at 1 kW; winter 1,000 kWh with a 10 kWh evening load. Results: about $530 a year on TOU-E, about $860 a year on R-3, plus $220 to $330 a season from Storage Rewards at 2 to 3 kW average
  • EnergySage Maricopa County marketplace data: about $10,600 installed for 13 kWh; retrofit quotes of $12,000 to $17,500
  • APS Storage Rewards program terms: $110 per average kW per summer
  • SRP Battery Partner program terms: $55 per kW, twice a year
  • SEIA and Benchmark, September 1, 2026: 6.2 GWh installed in Arizona in Q2 2026
  • Federal residential clean energy credit (25D) ended December 31, 2025
  • Arizona SB 1419, signed June 19, 2026: solar sales disclosure requirements