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Solar Water Heating

Solar-powered heating incentives.

Is solar water heating right for me?

Depending on the availability of unshaded sunlight and the amount of water usage at your home, solar water heating can be a very efficient technology. The decision to install one of these systems on your property should be made after you consider a variety of factors. Local building codes, availability of sunlight, maintenance requirements and the cost of other alternative energy options, should all enter into your decision to install a solar water heating system. In most populated areas of Arizona there is plentiful sunshine and current utility, state, and federal incentives make this a very economical choice.

What are the benefits of installing solar water heating systems?

Sunlight is a clean renewable energy resource that has been used for many years. Some benefits of solar water heating are:

  • Produces no emissions and is replenished naturally
  • Reduces greenhouse gases
  • Saves the release of 2 lbs. of carbon dioxide (CO2) for each kilowatt-hour (kWh) produced
  • Saves the use of one-half gallon of water for each kWh of solar energy produced
  • Saves the release of other emissions that result from the burning of fossil fuels such as nitrogen oxides, sulfur dioxide or mercury
  • Makes use of one of Arizona's greatest natural resources - sunshine
  • Provides customers with options to reduce their electric bills
  • Is very cost effective with payback periods of as little as five years

What incentives are available to UES customers?

UES offers 20-year up-front incentives (UFIs) for solar-powered heating systems (see Table 1).

Table 1. Maximum incentives for solar heating systems.

UFI1 — 20-Year REC Agreement
$.40 per kWh to a maximum of $1750.
  1. An up-front incentive (UFI) provides customers a one-time payment based on their system size. In turn the customer signs a credit purchase agreement assigning UES the renewable energy credits for 20 years.
Note: To qualify for the UFI your PV system must have at least a 20-year manufacturer's warranty.

Projects receiving a UFI can receive no more than 50% of the system cost in the total incentive payout. Also, UES incentives in combination with all federal and state credits can be no more than 85% of total project costs. A customer must cover at least 15% of total project costs.

Customers may qualify for federal and state tax credits to further reduce the cost of the system. Talk with a tax professional about current tax credits available to you for a renewable energy system. You can also view federal and state tax credits at


  • You must be a UES customer.
  • The solar water heating system must be installed at a UES service address.
  • You must purchase and install a qualifying solar water heating system for this incentive.
  • The solar water heating system must be located within the UES certificated service territory.

Ready to get started?

Click the sign-up button for installer resources such as forms, applications, agreements and more.



Learn more about the Renewable Energy Standard Tariff.

What size system would I need to meet most of my energy needs?

To choose a properly-sized water heating system, you'll need to consider the number of people living in the home, water usage, the size of the home and the output of the water heating system. A qualified installer can help you make the correct choice to meet your needs.

How do I find an installer and what qualifications do they need?

Click here to view a list of installers operating in UES service territories. We recommend that customers meet with at least two installers. Evaluate each contractor's experience and consider other factors. Do they have any unresolved complaints, judgments or liens? Will they provide a list of references?

The installer or contractor installing your system must have a license from the Arizona Registrar of Contractors that authorizes them to install solar water heating systems. This is necessary to receive an incentive under the Renewable Energy Credit Purchase Program (RECPP).

UES also requires the installer to possess an Arizona business license that is active and in good standing.

What is the application process?

Completed customer applications and the Renewable Energy Credit Purchase Agreements are reviewed by UES. Customers who are accepted into the program will receive an acceptance letter in the mail. The contractor may then proceed with system installation.

A City or County building permit is required for all residential systems and must a copy of permit must be on file with UES within 60 days of application acceptance or application will be cancelled. Your installer must arrange for the installed system to be inspected by City or County officials. Once proof of that inspection has been submitted, UES will arrange for a final inspection. Once a system passes the final inspection, UES will process the customer's incentive payment.

How long do I have after I receive my reservation confirmation to get my system installed?

Once customers receive their acceptance letter, also known as a "reservation confirmation," they have 180 days to install the system.

Can my incentive payment be assigned directly to my installer?

Yes, just complete the Assignment of Payment section on the Solar Water Heating application.

Will my solar water heating system have to replace my present system or be a supplement?

In general, the existing hot water tank will need to be replaced. However, with certain systems, your existing hot water tank can be retained to add additional storage capacity. The specifics of your existing water heater, the space available for the solar water heating tank and the type of solar water heating system you select will determine the options available to you. You should discuss your tank options with your installer.

What is the potential time period it will take for my system to pay for itself?

With the present tax credits and the incentives available from UES, the payback period for solar water heating system can be as little as five years or less.

What is the SRCC and how are systems certified under OG300?

The Solar Rating and Certification Corporation (SRCC) is an independent, non-profit organization formed in 1980 that certifies and rates the performance of solar energy equipment. OG-300 is an overall water heating system rating that encompasses the entire solar system (collectors, controls, storage tanks, heat exchangers, pumps, etc). This program integrates results of tests conducted on the collector and the system with computer simulations to determine whether systems meet minimum standards for durability, reliability, safety and operation. Factors that affect total system design, installation, maintenance and service are also evaluated. To learn more about the SRCC and system ratings, visit their website at

Does UES allow customers to install solar water heating systems themselves?

No. The installation of a solar water heating system is not a typical "do it yourself project" due to the following factors: proper use of dielectric fittings, cathodic protection measures, insulation, mounting, pump curve characteristics, pipe sizing, control wiring and low point drains/high point vents. All are important components that require experience to install correctly.

Equipment Requirements

  • Domestic solar water heating systems will be rated by the Solar Rating and Certification Corporation (SRCC) and meet the OG 300 system standard.
  • Systems that include OG-100 collectors, but are not certified under OG-300, will need to be verified by submitting either a testing certification for a substantially similar system prepared by a publicly funded laboratory or by submitting an engineering report stamped by a registered professional engineer detailing annual energy savings.
  • Solar heating systems will utilize OG-100 collectors.
  • Domestic Water Heating systems shall be selected and sized according to the geographic location and water needs of the specific application. Reservation requests will include a manufacturer's verification disclosing that the system size and collector type proposed are appropriate for the specific application, including certification that collector stagnation temperature shall never exceed 300 degrees Fahrenheit under any possible conditions at the location of the installation. The manufacturer’s verification may be presented as a manufacturer's product specification sheet and will be included in the reservation request.
  • Solar heating systems will be sized in conformance with the Solar heating Incentive Calculation Procedure.
  • Active, open-loop systems are not eligible for Renewable Energy Credit Purchase Program (RECPP) incentives except for those that have a proven technology or design that limits scaling and internal corrosion of system piping. They also must include appropriate automatic methods for freeze protection and prevent stagnation temperatures that exceed 250 degrees F. under all conditions at the location of installation. Details disclosing conformance with this exception shall be submitted as part of the manufacturer’s verification documentation.
  • Integrated Collector (IC) systems shall have a minimum collector piping wall thickness of 0.058 inches. Details disclosing conformance with this requirement shall be submitted as part of the manufacturer's verification documentation.
  • IC units shall include certification that collector stagnation temperature shall never exceed 250 degrees F. under any possible conditions at the location of the installation.
  • The hight limit on all Domestic Water Heating controllers shall be set no higher than 160 degrees F.
  • Active thermal storage for Solar heating systems shall use water as the storage element.
  • Contractors must provide a minimum of a five-year equipment warranty as provided by the system manufacturer, including a minimum warranty period of five years for repair/replacement service to the customer.
  • Domestic Water Heating systems that are installed as an addition to an existing system or are submitted as a customer-designed system or not certified to OG-300 must be specifically reviewed and approved by the utility.
  • The solar collector, heat exchangers and storage elements shall have an equipment warranty of at least 10 years to qualify for a UFI and at least five years to qualify for a PBI.

Installation Guidance

The system shall be installed with a horizontal tilt angle between 20 degrees and 60 degrees, and an azimuth angle of +/- 60 degrees of due south. It is recommended that collectors be positioned for optimum winter heating conditions at a minimum tilt angle of 45 degrees above horizontal, or as recommended by the manufacturer for the specific collector type and geographic location of installation.

All systems should be installed such that the energy collection system is substantially unshaded and should have substantially unobstructed exposure to direct sunlight between the hours of 9 a.m. and 3 p.m.

Heat exchange fluid in glycol systems should be tested, flushed and refilled with new fluid as necessary or at a minimum every five years or sooner per manufacturer’s recommendations.

It is recommended that the anode rod be checked and replaced per manufacturer’s recommendations, but no less frequently than every five years.

It is recommended that the system design include a timer, switch, or other control device on the backup element of the storage tank.

The collectors and storage tank should be in close proximity to the backup system and house distribution system to avoid excessive pressure or temperature losses.

It is recommended that in areas where water quality problems are reported to have reduced the expected life of a solar water heater, that a water quality test is performed for each residence to screen for materials that through interaction with the materials of the proposed solar water heating system may reduce the expected operational life of the system components. The customer should consider contacting the manufacturer to determine if warranty or operational life will be affected.

In areas subject to snow accumulation, sufficient clearance will be provided to allow a 12” snowfall to be shed from a solar collector without shadowing any part of the collector.

Each system shall have a comprehensive operation and maintenance manual at the customer’s site, which includes a spare parts list, data sheets and flow diagrams indicating operating temperatures and pressures, maintenance schedules and description of testing methods and each customer must complete an initial start up and operation training review with the contractor at the time of system start up.

Ball valves shall be used throughout the system. Gate valves shall not be used.

Pipes carrying heated fluids shall be insulated for thermal energy conservation as well as personal protection.

New Installer's Packet

Find the latest information for installers, including changes in program requirements, technical information and more.

Get Started

  • Contact a licensed installer. Please refer to the AZROC website.
  • Your installer will fill out and submit the appropriate application for your system.
  • A UES representative will review your application to ensure it conforms to program requirements.
  • Following review of your application, UES will notify you of the status of your reservation request.


Online Residential Solar Water Heating

Residential Solar Water Heating Application

Residential Solar Water Heating Agreement

Supplemental Program Information

PV Angle Chart

Service Requirements

Building Inspection Form

Assignment of Payment

Installation Certification

W9 Form