Purchased Power and Fuel Adjustment Charge

The Purchased Power and Fuel Adjustment Charge, or PPFAC, is a usage-based charge that reflects changes in the costs UniSource incurs to fuel its power plants and purchase energy for electric customers. The charge includes only costs that are not already incorporated in base power supply rates.

UniSource passes along these costs without any markup and earns no profit from this charge. The following questions and answers offer more information about the PPFAC.

Why does the PPFAC change from month to month?

The rate is adjusted monthly based on a 12-month “rolling” average of recent energy costs, with limits on month-to-month increases. Because of those limits, the PPFAC sometimes cannot keep up with significant changes in market energy prices. When that happens, the Arizona Corporation Commission (ACC) may approve a temporary surcharge or credit to recover or refund the difference between the amount UniSource has paid for energy and the amount it has recovered through the charge.

Have any surcharges or credits been added to bills?

There are no current PPFAC surcharges on customer bills. In May 2023, the ACC approved an adjustment to a PPFAC surcharge for use beginning that month to help recover costs that UniSource paid for fuel and power during extreme summer heat and throughout severe winter storms that affected the West. The temporary surcharge expired in December 2025.

How do these changes affect UniSource electric bills?

For residential customers with typical monthly usage of about 850 kWh, the elimination of the temporary PPFAC surcharge on Dec. 1, 2025 resulted in an estimated monthly bill reduction of about $19. The actual bill impacts vary based on individual usage.

Where can I view the current PPFAC rate?

The current rate is updated monthly and listed in our electric rates section.

How does the PPFAC appear on my monthly bill?

The PPFAC appears on your bill under the heading “Power Supply Charges” along with your base power supply rate.

Do other utilities have charges like this?

Yes. Similar components are included in the electric rates of UniSource's sister company, Tucson Electric Power, as well as in those charged by Arizona Public Service and many other electric utilities.

Do all customers have to pay this charge?

Customers of our GoSolar Shares program are not required to pay the PPFAC for solar power purchased through the program.

Will my bill be lower if I purchase solar power through the GoSolar Shares  program?

Our GoSolar Shares program is not designed to reduce customers’ electric bills. Rather, it offers an easy, affordable way to meet your electric needs with clean, renewable energy. Participants in the program can purchase 150 kWh “blocks” of solar energy produced by local photovoltaic arrays. Each block will replace the charges for an equivalent amount of traditional power at a cost that adds $3 apiece to participants’ monthly bills. The energy blocks will add to your monthly electric bill. But the price you’ll pay for each block will remain fixed for 20 years under ACC-approved program rules, so you may realize future savings if the cost of traditional energy resources increases. See the GoSolar Shares page for more information.

What can I do to reduce energy costs?

• Explore ways to save energy: Improving energy efficiency not only reduces your energy bills; it improves the comfort and quality of life for you and your family. Simple lifestyle modifications can make a big difference, especially if you conserve energy during times of peak usage. Cooling your home in the summer, for example, can be one of your largest energy expenses. The U.S. Department of Energy recommends setting your thermostat at 78 degrees in the summer to conserve energy and using fans to help you feel cooler.
• Find out if you qualify for payment assistance: We offer monthly low-income discounts. We can also help you determine if you’re eligible for federal rental assistance and can assist with payment plans if you’re falling behind.
• Consider some of our pricing plans and programs: Budget Billing helps level out your payments across the year, so your bills are more predictable, without those summer spikes.

You also might consider whether a different pricing plan could help you reduce your bill. Time-of-use rates offer discounts for usage during off-peak hours. Some also pair reduced energy charges with a “demand” charge that rewards customers who can limit their maximum energy use during on-peak hours. Customers with flexibility regarding when they use energy could find opportunities to reduce their monthly energy bills with demand pricing. See which plan might be a good fit with our Residential Lifestyle Calculator tool.