Recent Updates

The following items have been recently added or updated:

Some Almost Forgotten Solar History

Berkeley Lab’s “Utility-Scale Solar, 2021 Edition”

Electrification of transportation sector = More Renewable Energy Needed

Tucson Electric Power (TEP) to provide 70% of its energy from solar and wind by 2035

A link to a good article on What You Need to Know to make Sure Your Solar Rooftop is Properly Valued at Time of Sale: Is Solar Sexy When You Sell Your Home?

APS- Residential Battery Pilot Program

See the section "Some things to pay attention to in Arizona", click on the various tabs.

Solar Basics (Note- Items below shift Left-Right)

AriSEIA News - Keep up with the latest Arizona solar energy news! 


AriSEIA, Has published several articles or letters that are of interest to our Arizona solar community:


Featured (Note- Articles below shift Left-Right)

Some things to pay attention to in Arizona (Select Tab)

Click the ">" Tab to close any open tab



 Interesting Arizona Solar Stories

Coming soon, submit stories to

Other Announcements




Interesting Technology Updates -Click on a title below

  • - A radical idea to get a high-renewable electric grid

    This is an interesting approach to optaining very high penetration of renewables such as photovoltaics and wind.  At present most large installations operate under Power Purchase Agreements (PPA) wherein the economics are based on a sell all output at predetermined prices. This contrasts with standalone systems wherein the system size Read More
  • - Breakthrough Batteries Powering the Era of Clean Electrification

    - Breakthrough Batteries Powering the Era of Clean Electrification Battery Storage Costs Drop Dramatically, Making Way to a New Era. A recent Rocky Mountain Institute (RMI) report continues to confirm that clean electrification through batteries is advancing at impressive rates. Very interesting report: Breakthrough Batteries- Powering the Era of Clean Electrification Read More
  • - Changes impacting photovoltaic (PV) installations in the 2020 National Electrical Code (NEC)

    - Changes impacting photovoltaic (PV) installations in the 2020 National Electrical Code (NEC) A look at some of the more significant changes under consideration for the 2020 National Electrical Code (NEC) that will affect future distributed generation systems (solar electric wind, etc.). Article 690, Solar Photovoltaic (PV) Systems and Article 705, being renamed Interconnected Electric Power Production Sources, are specific to distributed generation. Read More
  • - Interesting Technology

    An assortment of links to interesting information   Semiconductor Nanowires Could Double the Efficiency of Silicon Solar Cells A p/n semiconductor junction is not the only way of converting sunshine into useful electrical energy.  Light consists of a flow of photons of various energy levels (colors).  See this article-Solar Cells.  Nanowires Read More
  • 1

General News

Caution- News leads open in new windows. Warning- These news links are automatically generated by others such as Google News and are not reviewed by the Arizona Solar Center, Inc. We are not responsible for link content.

Interesting Videos

Too Much Renewable Energy in Australia?

Electric Utilities worldwide are experiencing problems with system management with large PV systems being added to their generation mix.

In Australia Nine more solar farms could have output cut to zero due to system strength issues

Earlier in Australia AEMO slashes output of five big solar farms by half due to voltage issues

The above articles reference additional similar problems.

In Arizona TEP has identified areas in there service territory that are already saturated with PV systems TEP PV Saturation Maps

Understanding your APS Connected Photovoltaic System- Net Metering

If you have a photovoltaic (PV) system connected to APS and do not have other monitoring of the PV system such as that provided by most inverter manufacturers, it is not easy to determine the solar production that corresponds with the monthly electric bill.  APS requires a solar production meter and this data is recorded and made available to the customer, but with a little difficulty.  The following example is based on the now grandfathered 'Net Metering' (rate rider EPR-6) wherein any excess PV production, measured in kilowatt-hours (kWh) is used to offset energy delivered by APS.  This method has been replaced by a system APS calls RCP, utility speak called 'Resource Comparison Proxy' (note that the APS website was developed by utility personnel using their view of the situation, not the customer view). The Solar Center intends to repeat the following procedure later with examples based on RCP.

Look at the recent example of an APS electric bill and see if you can determine the solar production:

APS web 6m

The APS bills show only that 186 kWh in this case was net metered.  The bill does not show the solar production that was directly used, to determine this one has to have an APS web account (free) and has to go online to learn more. There is a lot of data available.  Note the 'Meter reading' dates above, this will be used later to calculate the solar production. Using a browser such as you are using to view this article, go to

There is presently a Capcha screen to prove that a person and not an automated computer is accessing the website.  Enter the requested data.  

APS web 1b

Enter your APS username/password then click login.  If you do not already have a username and password, click on 'register'. The following is typical.

APS web 1

Next select 'daily and hourly usage'.  Solar production is a subset of usage for some APS reason.

APS web 1a

There are four types of data available and a calendar to select the dates to view.  See the red instructions in the examples below.  In APS jargon 'received usage' is solar production. This screen shows the solar production graphically, good for seeing relative production that depends on the sunshine and to a lesser extent the air temperature. Clicking on the 'Day' tab will expand that day, otherwise a month (or the current month to date) is displayed.

APS web 2

This view shows the pattern of the energy drawn from APS.  Actual total usage at a specific time will be higher since PV system production will be used directly if there is enough usage at the specific instant.

APS web 3

 APS web 4

APS web 5

Note that on each of the above examples, there is a down arrow next to the 'for service at' section and that clicking on this down arrow shows a second service, the PV production Meter with an '*'. The address is blurred in this example. Select the line with the *.

APS web 11

The production data is displayed in two formats, a bar graph for the month, and a graphical format for the week.

Hal Jul 2019 PV

Hal Aug 2019 PV Hr

In order to get values for calculations, the monthly summary data needs to be downloaded as Excel files, usually for the two months that include the date range of the electric bill.  With the 'daily energy useage' tab selected, select the first month of the range (click on any date), then click on the 'download meter data' text link over the calendar.  This will download a file named 'Excel.xlsx' ( or Excel(y).xlsx where 'y' is a digit, added by your computer when 'Excel.xlsx' already exists).  A spreadsheet program is needed to open and view these files, Excel for example.  Select the 'daily energy usage' and 'delivered useage' tabs.  The Excel data will look like this:

APS web 8 The values for the billing date range, July 25 to August 23 in this example, need to be added.  This can be done with the spreadsheet program or manually.  In this example the sum is 711.5 kWh. This is not straight forward since the values shown are actually text and Excel can not directly add them.  Use the =value(cell) function in another column to convert the text to actual values.  Now that the actual solar production is known, the below  chart shows the relationship of these values.

APS web 9

The calculation of Home useage is (Solar Production) + (Purchased from APS) - (Sold or net metered to APS).


Arizona’s Salt River Project Utility Challenged On High Rooftop Solar Rates

In 2015 SRP became anti-solar when it adopted special solar rates (E27) with some high demand charges, etc.  SolarCity, later acquired by Tesla, challenged SRP’s discriminatory solar rates on antitrust grounds. SolarCity/Tesla took the case to the Supreme Court after a lower court rejected its request to dismiss the case. SRP reached a settlement with Tesla before the Supreme Court hearing, and the discriminatory fees were left in place. As part of the settlement SRP agreed to purchase a 25 megawatt/100 MW-hour battery energy storage system from Tesla. This meant that the basic reasons for the lawsuit, challenging the discriminatory rates, were not subject to court review and a chance to rule against SRP. The Center for Biological Diversity filed an Amicus brief against SRP’s motion to dismiss in order to have the Supreme Court consider the antitrust grounds.  

The SRP rates have been proven to stifle rooftop solar, reducing new installations in SRP service areas while installations in other areas of Arizona increased.  SolarCity claimed that SRP’s discriminatory solar rate structure is an obstacle to clean energy transition, because it undermines the value of homeowner investment in these systems. The solar rates were not examined by the courts, SRP basically claimed that it was exempt from regulation in this situation.

The Center for Biological Diversity is an Arizona-based non-profit environmental organization dedicated to the preservation, protection and restoration of biodiversity, ecosystems, and public health. On behalf of its more than 1.5 million members and online activists nationwide, including more than 890 members, and over 15,000 supporters, who live in SRP service territory, the Center advocates for a rapid transition to a clean and just energy system that optimizes renewable energy sources such as distributed solar in order to reduce U.S. greenhouse gas (“GHG”) emissions and combat climate change.

The Center filed an Amicus brief to present three discrete arguments against SRP’s motion to dismiss. First, SRP should not be permitted to rely on state action immunity to shield its discriminatory rate structure from antitrust liability, and certainly not at the pleading stage. Second, state-action immunity for utilities like SRP should in any event be constrained to open the door for distributed solar competition. And finally, SRP is violating the Equal Protection clause because its anti-solar electricity rates have no rational basis.

Charles W. Thurston has a good article on this subject in CleanTechnica:Arizona’s Salt River Project Utility Challenged On High Rooftop Solar Rates

Univ. of Arizona - Institute for Energy Solutions May 2019

Some interesting content from the May 2019 newsletter

UA Institute for Energy Solutions logo

June 7th
10 AM - Noon

Indige-FEWSS mobile water purification unit demonstration

Dr. Karletta Chief, Navajo Nation President, Jonathan Nez, Diné College President, Dr. Charles Roessel, and Diné College Students and Indige-FEWSS fellows will discuss and demo the water purification unit at Diné College, Tsaile Campus.

Water Purification UA

Imagine Adaptation | Finding Solutions fo the Food, Energy, Water, Nexus January 2019, British film company-One World Network, gathered UA researchers and community delegates to answer the question "What is being done to address the big issues at the energy, water, food nexus that will secure our world as we know it for the future?" Out of this exploratory emerged a documentary which takes a look at the many branches of UA's collaborative E-W-F research. We invite you to watch this exciting new video!


  • Welcome to the Arizona Solar Center

     This is your source for solar and renewable energy information in Arizona. Explore various technologies, including photovoltaics, solar water heating, solar architecture, solar cooking and wind power. Keep up to date on the latest industry news. Follow relevant lectures, expositions and tours. Whether you are a homeowner looking to become more energy efficient, a student learning the science behind the technologies or an industry professional, you will find valuable information here.
  • About The Arizona Solar Center

    About The Arizona Solar Center Arizona Solar Center Mission- The mission of the Arizona Solar Center is to enhance the utilization of renewable energy, educate Arizona's residents on solar technology developments, support commerce and industry in the development of solar and other sustainable technologies and coordinate these efforts throughout the state of Arizona. About the Arizona Solar Center- The Arizona Solar Center (AzSC) provides a broad-based understanding of solar energy, especially as it pertains to Arizona. Registered Read More
  • 1