Salt River Project Solar Options and Rate Plans

Salt River Project (SRP) is one of Arizona's two dominant electric utilities and operates under a distinct rate and program structure that differs substantially from other Arizona providers. This page documents SRP's solar-specific rate plans, billing mechanics, interconnection requirements, and the tradeoffs solar customers face when operating within SRP's service territory. Understanding these structures matters because SRP's rate design has a measurable effect on the financial performance of residential and commercial solar installations.

• Definition and scope
• Core mechanics or structure
• Causal relationships or drivers
• Classification boundaries
• Tradeoffs and tensions
• Common misconceptions
• Checklist or steps (non-advisory)
• Reference table or matrix

Definition and scope

Salt River Project Agricultural Improvement and Power District is a political subdivision of the State of Arizona, organized under Arizona Revised Statutes Title 48, Chapter 17. Unlike investor-owned utilities such as Arizona Public Service (APS), SRP is not regulated by the Arizona Corporation Commission (ACC) for rate-setting purposes. This structural difference — a public power district governed by an elected board rather than a state commission — means that SRP sets its own solar rate plans through an internal board approval process rather than ACC dockets.

SRP's service territory covers approximately 2,900 square miles in the greater Phoenix metropolitan area, including Tempe, Chandler, Mesa, Gilbert, Scottsdale (portions), and surrounding communities. Solar customers within this territory connect under SRP's E-27 Customer Generation Price Plan or related successor plans, which are the primary solar-specific rate structures SRP has offered since 2015.

For foundational context on how Arizona solar energy systems function, see the conceptual overview of how Arizona solar energy systems work.

Scope boundary: This page covers SRP's service territory and SRP-specific rate plans only. It does not apply to APS customers, Tucson Electric Power (TEP) customers, or customers served by rural cooperatives such as Sulphur Springs Valley Electric Cooperative. For the broader regulatory context for Arizona solar energy systems, including ACC-regulated utilities, separate coverage applies. Municipal utilities operating within Arizona (such as the City of Prescott or Navajo Tribal Utility Authority) are also outside this page's scope.

Core mechanics or structure

SRP's primary solar rate plan as of the plan's post-2015 structure is built on a demand-based billing model, which is a fundamental departure from the consumption-only billing used by most residential utilities nationwide.

E-27 Customer Generation Price Plan — structural components:

1. Demand charge: SRP measures the customer's peak 30-minute demand interval during on-peak hours (generally 1 p.m. to 8 p.m. during summer months). The demand charge is applied per kilowatt (kW) of that peak demand, assessed monthly.
2. Energy charge: A per-kilowatt-hour (kWh) consumption charge applies to all electricity drawn from the grid, segmented by on-peak and off-peak periods.
3. Export credit: Solar energy exported to the grid earns a credit, but at a rate that reflects SRP's avoided cost rather than the full retail rate. SRP's export credit structure is lower than one-for-one net metering, which distinguishes it sharply from historical net metering policies in other states.
4. Monthly minimum bill: SRP applies a minimum monthly bill amount regardless of solar generation output, which limits the degree to which solar can offset the base service charge.

SRP also offers a Time-of-Use (TOU) export price plan and has periodically structured pilot programs targeting solar-plus-storage configurations. The Arizona solar battery storage overview page addresses how storage pairing interacts with demand-charge rate structures.

Interconnection for residential solar systems at SRP requires submission through SRP's online Customer Generation Interconnection application. SRP uses the IEEE 1547-2018 standard as the technical baseline for inverter performance and grid interconnection requirements. IEEE 1547-2018 mandates specific anti-islanding, voltage ride-through, and frequency ride-through capabilities for all distributed generation equipment.

Causal relationships or drivers

SRP's rate structure for solar customers emerged from a board decision in 2015 that introduced the demand charge framework. The board cited grid infrastructure cost recovery as the primary driver: rooftop solar customers who self-generate reduce their volumetric energy purchases but continue to use transmission and distribution infrastructure during peak demand periods.

The demand charge model attempts to align each customer's grid infrastructure contribution with their actual peak demand behavior rather than their total consumption. Because residential solar systems typically generate most output during midday hours (roughly 10 a.m. to 2 p.m.) and SRP's on-peak window extends to 8 p.m., solar generation alone does not reliably suppress the demand measurement window that determines the monthly demand charge.

A second causal driver is SRP's avoided-cost export pricing. SRP's board-approved avoided cost rate reflects wholesale electricity market prices rather than retail rates. Because Arizona's high solar irradiance generates abundant midday photovoltaic output across the region (Phoenix averages approximately 299 sunny days per year, per National Renewable Energy Laboratory's PVWatts data), midday grid export from distributed solar coincides with periods of lower wholesale market value, further suppressing the credit rate relative to retail consumption pricing.

Battery storage systems paired with solar can shift generation dispatch into the on-peak window, directly reducing the measured demand charge. This relationship makes the financial case for storage pairing stronger under SRP's rate structure than under flat-rate volumetric billing utilities. For a broader overview of Arizona solar system types and configurations, visit the Arizona grid-tied vs. off-grid solar systems page.

Classification boundaries

SRP solar rate plans divide customers into distinct categories based on system type, size, and export behavior:

Residential solar customers fall under the E-27 Customer Generation Price Plan (or its current successor plan designation). This applies to systems typically below 100 kW nameplate capacity serving a single-family or small multifamily account.

Commercial solar customers operate under SRP's commercial rate schedules, which include separate demand ratchet provisions. Commercial interconnection thresholds and review timelines differ from residential processing.

Community solar subscribers participate through SRP's EarthWise Energy program, which allows customers without rooftop access to subscribe to blocks of renewable energy without installing on-site generation. This is classified separately from customer generation programs because no physical interconnection occurs at the subscriber's premises.

Solar-plus-storage systems may qualify for specific SRP pilot programs. Storage systems dispatching solely to offset on-site load (not exporting battery-stored energy to the grid) are classified differently than systems configured for grid export from storage, which triggers additional interconnection review.

The Arizona community solar programs page covers the community solar classification in greater detail, including SRP EarthWise block subscription mechanics.

Tradeoffs and tensions

The demand charge structure creates a direct tension between system size optimization and bill reduction. Oversizing a solar array to maximize total energy production does not reduce the demand charge if peak demand still occurs during a non-solar hour. A customer with a 10 kW system who runs air conditioning at 7 p.m. on a summer evening may see no demand charge reduction relative to a non-solar customer, despite generating significant daytime energy.

Export credit valuation represents a second tension. Because SRP's export credits are calculated at avoided cost rather than retail rate, the effective value of excess generation is lower than what a customer would pay to purchase that same electricity. Net annual financial benefit calculations must account for this asymmetry, which has caused disagreement between solar industry stakeholders and SRP's board during public comment periods on rate proposals.

A third tension involves the minimum bill provision. Solar customers who significantly reduce consumption still pay a base amount each month, creating a floor on bill savings that limits payback period optimization, particularly for smaller systems sized purely for energy offset.

The Arizona net metering policies and utility billing page provides a comparative frame for how SRP's export credit approach differs from ACC-regulated utilities that operate under net metering frameworks governed by ACC decisions.

The broader context of solar financing options in Arizona is directly affected by these rate structures, as lenders and lease providers model projected savings based on utility rate assumptions that differ substantially between SRP and ACC-regulated territories.

Common misconceptions

Misconception 1: SRP offers net metering equivalent to APS or TEP.
SRP is not subject to ACC net metering rules because it is not an ACC-regulated investor-owned utility. SRP's export credit rate is not a one-for-one retail offset. Customers expecting retail-rate net metering based on statewide policy discussions are applying a framework that does not govern SRP.

Misconception 2: A larger solar array always produces greater bill savings under SRP.
Under a demand-charge billing model, total kilowatt-hours generated is not the primary savings driver. The degree to which solar generation reduces the peak 30-minute demand interval during on-peak hours determines the demand charge component, which is often the largest single line item for solar customers on the E-27 plan.

Misconception 3: SRP's rate plans for solar customers are set by the Arizona Corporation Commission.
The ACC has no jurisdiction over SRP's rate-setting process. SRP's board of directors approves rate plans through a public meeting and vote process governed by state statute, not ACC docket proceedings.

Misconception 4: Installing solar at an SRP property automatically grandfathers the customer into legacy rate terms indefinitely.
SRP's rate plans are subject to board revision. Customers who enrolled under a specific plan version should review SRP's published notices regarding plan transitions, as terms have changed since the original 2015 E-27 introduction.

For a complete introduction to how Arizona solar systems interconnect with utility infrastructure, the Arizona utility interconnection process page covers the technical and administrative steps applicable across utilities, with SRP-specific distinctions noted.

Checklist or steps (non-advisory)

The following steps describe the general process sequence for a residential customer seeking to install solar within SRP's service territory. This is a procedural reference, not professional or legal advice.

1. Confirm SRP service territory — Verify the property address falls within SRP's service boundary using SRP's online address lookup tool at srpnet.com.
2. Review current solar rate plan terms — Download SRP's current E-27 Customer Generation Price Plan schedule and associated terms from SRP's published rate schedule library.
3. Obtain equipment specification documentation — Confirm the proposed inverter and system components meet IEEE 1547-2018 interconnection requirements. SRP's interconnection application requires equipment specification sheets.
4. Submit SRP Customer Generation Interconnection Application — Complete the application through SRP's online portal, including system design specifications, single-line electrical diagrams, and equipment data sheets.
5. Await SRP technical review — SRP conducts a technical feasibility review. Residential systems typically below 25 kW follow a simplified review track; larger systems may require a full interconnection study.
6. Obtain local building permit — Separate from SRP's interconnection approval, the local municipality (Mesa, Chandler, Tempe, Gilbert, etc.) requires a building permit for the physical installation. Refer to permitting and inspection concepts for Arizona solar energy systems for jurisdiction-specific information.
7. Complete installation and inspection — The installation must pass the local authority having jurisdiction (AHJ) inspection before SRP will authorize energization.
8. Receive Permission to Operate (PTO) — After SRP confirms the installation meets interconnection requirements and the AHJ inspection is passed, SRP issues Permission to Operate, authorizing the system to connect to the grid.
9. Enroll on SRP solar rate plan — Rate plan enrollment occurs after PTO issuance. Customers should confirm which current plan designation applies at enrollment date.
10. Monitor system performance against demand windows — Track system output relative to SRP's on-peak demand measurement windows to assess demand charge impacts. See Arizona solar energy system monitoring concepts for monitoring framework details.

For a broader introduction to Arizona solar energy and how to navigate utility interactions, the Arizona solar authority home page provides orientation to all major topic areas covered on this site.

Reference table or matrix

SRP Solar Rate Plan Comparison Matrix

SRP On-Peak Period Reference (Summer vs. Winter)

Note: SRP publishes official on-peak hour definitions in its current rate schedule documents. Customers should verify current plan terms directly from SRP's published rate schedules.

References

• Salt River Project (SRP) — Electric Price Plans
• Arizona Revised Statutes Title 48, Chapter 17 — Agricultural Improvement Districts
• IEEE 1547-2018 — Standard for Interconnection and Interoperability of Distributed Energy Resources
• National Renewable Energy Laboratory — PVWatts Calculator
• SRP EarthWise Energy — Renewable Energy Programs
• Arizona Corporation Commission — Utilities Division
• U.S. Department of Energy — Distributed Generation Interconnection