Exhibit 99.1

UNS ENERGY REPORTS THIRD QUARTER 2012 EARNINGS,

NARROWS 2012 EARNINGS GUIDANCE RANGE

Tucson, Ariz. – UNS Energy Corporation (NYSE: UNS) today reported third quarter 2012 net income of $50.7 million, or $1.21 per diluted share of common stock, compared with net income of $59.7 million, or $1.46 per diluted share in the same period last year.

TEP reported net income of $44.6 million for the third quarter of 2012, 17 percent below net income of $53.9 million in the third quarter of 2011.

“Although earnings continue to be pressured by TEP’s retail rate freeze, our operating performance remains strong. We expect to hold full year operating and maintenance expenses at the same level as 2009 while maintaining a high level of reliability and safety,” said Paul Bonavia, UNS Energy’s Chairman and Chief Executive Officer. “Our power plants ran exceptionally well this summer and our safety record to date is outstanding.”

A 2008 settlement agreement approved by the Arizona Corporation Commission (ACC) will keep TEP’s non-fuel base retail rates unchanged until TEP’s pending rate request is finalized and approved in 2013. During this rate freeze period, TEP’s retail sales volumes have remained virtually unchanged due to general economic conditions and energy efficiency requirements passed by the ACC. In order to partially mitigate the effect of stagnant energy demand on UNS Energy’s financial performance, the company successfully aligned operating expenses with retail energy sales through the implementation of new operating efficiencies and cost containment measures.

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However, TEP faces cost pressures associated with capital investments in order to maintain safe and reliable service that are not reflected in current retail rates. In July 2012, TEP submitted an application with the ACC seeking its first non-fuel base rate increase since 2008. The filing requests a non-fuel base rate increase of approximately $128 million, or 15 percent, to be effective no later than August 1, 2013.

Tucson Electric Power

Retail kWh Sales and Revenues

TEP’s retail kWh sales decreased by 3.6 percent in the third quarter, due in part to a 12.2 percent decline in cooling degree days compared with the third quarter of 2011. The decrease in retail sales volumes led to a 4.0 percent, or $7.3 million, decrease in TEP’s retail margin revenues compared with the third quarter of 2011.

Other Operating Expenses

TEP’s base O&M expense was $1.2 million lower than the third quarter of 2011. Base O&M excludes costs directly offset by customer surcharges and third-party reimbursements. In the third quarter of 2012, depreciation and amortization expense increased by $2.3 million as a result of additional plant-in-service compared with the same period last year.

Other Factors

TEP’s third quarter 2012 results include an after-tax loss of approximately $1.1 million related to an unplanned outage at Springerville Unit 3, a power plant that TEP operates on behalf of another party. Results in the third quarter of 2011 include an after-tax gain of approximately $4.5 million related to the settlement of a transmission dispute.

Year-to-Date Results

In the first nine months of 2012, TEP reported net income of $65.0 million compared with net income of $83.8 million in the same period last year. That decrease was due to: lower retail and long-term wholesale margin revenues; higher depreciation and amortization expense; a loss recorded in the first nine months of 2012 related to the operation of Springerville Unit 3, described above; and the gain recorded in the first nine months of 2011 related to the settlement of a dispute, described above.

UNS Gas and UNS Electric

UNS Gas reported a net loss of less than $1 million in the third quarters of 2012 and 2011.

UNS Electric reported net income of $6.4 million in the third quarter of 2012 compared with $7.0 million in the third quarter of 2011. The decrease was due to: lower retail kWh sales due in part to a 5.5 percent decline in cooling degree days; and higher depreciation and amortization expense related to an increase in net plant in service.

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Seasonality of Earnings

The net income and results of operations of TEP as well as of UNS Gas and UNS Electric – operating subsidiaries of UniSource Energy Services (UES) – are seasonal in nature. TEP and UNS Electric typically record the majority of their net income during the second and third quarters when hot weather contributes to higher energy consumption. TEP’s retail rates, which include higher charges for higher levels of energy use, also shift a larger share of the company’s earnings into those periods.

Energy demand from UNS Gas customers typically peaks during the winter. Accordingly, UNS Gas typically records the majority of its net income during the first and fourth quarters.

Net Income and Earnings Per Share Summary

UNS Energy believes the presentation of TEP, UNS Gas and UNS Electric net income or loss on a per basic UNS Energy share basis (which are non-GAAP financial measures) provides useful information to investors by disclosing the results of operations of its business segments on a basis consistent with UNS Energy’s reported earnings or losses.

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Conference Call and Webcast

The company will host a conference call on Friday, November 2, 2012 at 1 p.m. ET. To participate in the call, please dial in 5 to 10 minutes prior to the start time. A reference code is not necessary to access the live call.

Dial-in number: (800) 695-3360

The conference call also can be heard live online at uns.com.

A telephone replay will be available for seven days.

Replay number: (800) 633-8284

Reference code: 21609581

In conjunction with this earnings announcement, UNS Energy provided additional information on its performance during the third quarter of 2012. These materials were filed with the Securities and Exchange Commission and are also available at uns.com.

UNS Energy is a Tucson, Arizona-based company with consolidated assets of approximately $4 billion. UNS Energy’s primary subsidiaries include Tucson Electric Power, which serves more than 405,000 customers in southern Arizona, and UniSource Energy Services, provider of natural gas and electric service for about 240,000 customers in northern and southern Arizona.

Visit uns.com for more information about UNS Energy and its subsidiaries.

This release contains forward-looking information that involves risks and uncertainties, including factors that could affect UNS Energy’s ability to reach the 2012 earnings guidance. These risks and uncertainties include, but are not limited to: state and federal regulatory and legislative decisions and actions; regional economic and market conditions, which could affect customer growth and energy usage; weather variations affecting energy usage; the cost of debt and equity capital and access to capital markets; the performance of the stock market and changing interest rate environment, which affect the value of the company’s pension and other postretirement benefit plan assets and the related contribution requirements and expense; unexpected increases in O&M expense; resolution of pending litigation matters; changes in accounting standards; changes in critical accounting estimates; changes to long-term contracts; the cost of fuel and power supplies; performance of TEP’s generating plants; and other factors listed in UNS Energy’s Form 10-K and 10-Q filings with the Securities and Exchange Commission. The preceding factors may cause future results to differ materially from outcomes currently expected by UNS Energy.

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UNS ENERGY 2012 RESULTS

N/M—Not Meaningful

Reclassifications have been made to prior periods to conform to the current period’s presentation.

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UNS ENERGY 2012 RESULTS

N/M—Not Meaningful

Reclassifications have been made to prior periods to conform to the current period’s presentation.

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TUCSON ELECTRIC POWER COMPANY 2012 RESULTS

N/M—Not Meaningful

Reclassifications have been made to prior periods to conform to the current period’s presentation.

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TUCSON ELECTRIC POWER COMPANY 2012 RESULTS