Reliability and Grid Resiliency | Investment | Distributed Energy Integration | Innovative Solutions | NERC Compliance

Updated: March 2021

Nearly 1.3 million homes and businesses rely on us for safe, reliable power. The electric transmission and distribution system is evolving, and we are working to remain at the forefront of innovation in our rapidly changing industry. We will continue to invest in new grid technologies, system upgrades and related management systems through several project initiatives.

Reliability and Grid Resiliency

Effective planning, operation and maintenance of generation, transmission, distribution and customer connected resources is essential to providing reliable service and enhancing a resilient grid.

APS is strategically deploying a variety of technologies that are intended to allow customers to better manage their energy usage, minimize system outage durations and frequency, enable customer choice for new customer-sited technologies, and facilitate greater cost savings to APS through improved reliability and the automation of certain distribution functions.

Notwithstanding the challenges presented by the COVID-19 pandemic and the hottest summer on record, APS continued to provide reliable service to its customers in setting an all-time high peak energy demand and achieved strong reliability results. While some utilities in California and Arizona were forced to declare energy emergencies in the summer of 2020 because of extreme heat, we did not. Our ability to avoid an energy emergency was the result of careful long-term planning, resource adequacy, flexibility, and innovative customer programs.



When measuring reliability, our performance results continue to be strong. APS is among the most reliable providers in the country. We currently rank in the top 25% of electric utilities across the nation for frequency of outages in 11 of the past 12 years and within the top 25% for duration of outages in 10 of the past 12 years (2008-2019, results are not yet available for 2020). In other words, outages are few and far between, and we quickly restore power for customers. 


To keep our service reliability high and enhance grid resiliency as our state grows, we deploy programs to monitor the health of our system and prioritize investments on behalf of customers. APS proactively identifies equipment that could be at risk of failure and develop plans for replacement and upgrades that will demonstrate a direct reliability benefit to our customers.   

We monitor the health of our system for indications of failure, replacing equipment that has potential for failure and/or that has become aged-out, faulty or damaged. We add new technology/equipment to make our grid more resilient and flexible, including projects adding capacity to accommodate areas of high distributed energy resources, and integrating technology that allows us to remotely and more quickly detect and restore outages. 

We build facilities to serve (or provide access to) new customers. This can be additional customers within an already developed area or new customers where there was no previous infrastructure. 

Each year we invest more than $1 billion to upgrade and expand the infrastructure of the energy grid covering our vast service territory. That is part of how we are partners in Arizona’s prosperity – forecasting and meeting the state’s energy needs as it grows and brings new developments of all kinds. 

Our investments in infrastructure for 2021 are projected to be $1.5 billion, up from $1.26 billion in 2020. Of that, $762 million have been budgeted for 2021 projects related to transmission and distribution (T&D), the avenues by which we deliver our power into the communities and neighborhoods we serve. 

Distributed Energy Resource Integration

Distributed resource integration presents new challenges to traditional utility planning and operation. APS customers interconnected well over 118,500 residential rooftop photovoltaic systems by the end of 2020 and have integrated over 31,000 connected devices such as smart thermostats, more than 880 solar-plus-storage installations, and 1,837 Commercial photovoltaic installations and emerging electric vehicle infrastructure.

These distributed technologies require new utility side monitoring, and control technologies that can accommodate the operational changes these resources bring. Challenges of aligning solar production with system peak, managing weather-dependent intermittency, and related power quality issues must be addressed via technology solutions and intelligent grid operations. Our grid modernization efforts facilitate the integration of these resources while simultaneously ensuring high reliability and power quality by providing system operators with greater visibility, intelligence, and control options future.

Innovative Solutions

Advanced Grid Technologies. Integrating advanced transmission and distribution system technologies enables us to build a modern, flexible grid that enhances our operational capabilities to serve customers with a new suite of tools and services, and allows more cost-effective and reliable service, with increasing levels of customer-connected technologies.

APS continues to pursue and implement advanced grid technologies, including transmission and distribution system technologies and digital meters enabling two-way communications between the utility and its customers. Customers have sent a clear signal with the high volumes of customer-connected technologies and as a service provider we must innovate to optimize all available tools and grid resources to maintain reliability. APS plans to invest in advanced grid technologies, system upgrades and related management systems through a number of initiatives. In the past three years, more than 1,000 advanced grid devices have been installed on the APS system.

Read more about our customer technologies and programs on our customers page.

Energy Storage. APS deploys a number of advanced technologies on its system, including energy storage. Storage can provide capacity, improve power quality, be utilized for system regulation, integrate renewable generation, and, in certain circumstances, be used to defer certain traditional infrastructure investments. Energy storage can also aid in integrating higher levels of renewables by storing excess energy when system demand is low and renewable production is high, and then releasing the stored energy during peak demand hours later in the day and after sunset. APS is utilizing grid-scale energy storage projects to benefit customers, to increase renewable utilization and to further our understanding of how storage works with other advanced technologies and the grid.  

In addition to aligning solar production and customer energy consumption, batteries work to improve grid resiliency. In the event of a grid outage, a utility or a customer with a battery only installation can keep critical loads energized in the unlikely event of a grid outage.   

Read more about our energy storage (and other clean generating technologies) on our clean energy page. 

Microgrids. APS expects microgrids to play an increased role in how we support critical customers and economic development while strengthening the grid. Microgrids are beneficial for our system and our customers as they increase reliability and resiliency by supporting the load where the microgrid is sited; a customer with an on-site microgrid rarely, if ever, experiences a power outage. Microgrids are small-scale power generating facilities— installed on-site at the customer premise that can provide backup power in case of a grid outage but can also operate while utility connected to deliver peak capacity service and frequency response. This means that the individual customer has reliable and resilient service, but that all utility customers see benefit to APS that benefits additional customers.

By sharing microgrid development costs with customers, increasingly cost-effective economic deployment of new grid resources may be achieved. A microgrid’s fast-acting capabilities also enhance grid resilience and flexibility by providing important peak resources and ancillary services such as frequency response, which can lessen the occurrence and impact of power outages. With the potential to add energy storage to these microgrids, their responsiveness can be improved along with increasing flexibility and emissions reductions. Microgrids offer great potential for developing grid innovation. For example, we have two patents, one that was awarded in March 2020 and the other expected to be awarded in early 2021 on the systems developed in-house that enable our microgrids to perform autonomous frequency response. 


The microgrid at Marine Corps Air Station Yuma can supply complete backup power to the base in case of a grid outage.

Advanced Distribution Management System. As part of our continuous quest to improve reliability for our customers, in just 10 years we have transitioned operations from using paper wall maps and push pins to track outages and crew movement, to utilizing a state-of-the art digital advanced distribution management system (ADMS) for outage management, with mobile device capability and advanced operations support features. The ADMS Program is a major initiative that increases operator visibility and control, to provide overall distribution system situational awareness and drive operating efficiency. With the latest version and security implemented in 2020, APS is focused on improvements to power quality and reliability for our customers through continued application growth with automation of both fault location, isolation, and service restoration and optimized voltage performance. Together, the projects allow our customers to benefit from improved system reliability, increased outage information, and enable effective customer technology integration, while providing grid operators with tools to provide safe, reliable, resilient and quality service. The ADMS Project and future initiatives are a big step toward integrating flexible and dynamic technology that will allow us to operate the grid of the future.

Drone Technology and Predictive Maintenance. Our unmanned aircraft system (UAS) program continues to grow and provide benefits to our customers. UAS technology, commonly referred to as “drones,” allows field personnel and engineers to work safer in hazardous terrain, collect hard-to-reach imagery, and evolve engineering practice at lower costs than traditional methods for power line patrols and inspections. We currently operate a cutting-edge fleet of drones with a continued dedication to strategy, training and program development that promises to improve reliability and safety performance. We have ensured that our UAS program meets all Federal Aviation Administration requirements. UAS-mounted thermal imaging cameras and high-resolution sensors are used to inspect distribution, transmission, generation and communications equipment to determine the overall health of systems. In addition to providing improved inspection data, UAS helps us respond more quickly to outages and issues affecting the grid, such as storm damage. In the future, they may be used to survey remote transmission and distribution lines using machine learning to detect anomalies, reducing the cost to perform annual inspections for proactive maintenance.

NERC Compliance

APS takes its commitment to doing what is best for the people and prosperity of Arizona to heart with the mission to serve our customers with clean, reliable and affordable energy. 

Any organization associated with electrical generation, transmission, and interconnection of the bulk power system in the United States, Canada, and part of Mexico is subject to North American Electric Reliability Corporation (NERC) standards.  Each of the more than 900 NERC reliability requirements has been developed to address a risk associated with planning and operating the North American bulk power system.  For instance, these risks may be associated with sophisticated physical and cyber-threats, severe cold or hot temperatures, extreme natural events, challenging oil and natural gas interdependencies, and/or a changing resource mix.  

While all such applicable responsible entities have the common goal to maintain compliance, APS has the mindset that compliance is a natural byproduct of careful and intentional reliability and security practices. Stated another way, compliance does not occur by accident. 

At APS, overall reliability and security is a shared responsibility with clear roles defined for oversight and accountability throughout the organization. APS maintains a constant state of readiness including documented processes and tools to address each applicable requirement. Moreover, APS has processes in place for identifying, assessing and prioritizing risks to achieving reliability, security and compliance objectives. APS’s NERC internal control program is developed to address these risks. The result is a tailored and continually enhanced approach to identifying concerns before they have an impact to providing safe, affordable electricity to our customers.

APS is constantly on the leading edge of developing tools and awareness to achieve safe, reliable and secure energy generation and delivery. This includes staying on the forefront as new standards are developed, leveraging industry lessons learned, proactively implementing above–and-beyond practices and conducting stakeholder outreach building upon a long history of productive relationships in the industry.

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