Redefining Grid Reliability: Hydro One’s Zerdin on Integrating DERs and Customer Needs

The Shifting Definition of Reliability and Resiliency for Utilities

For decades, the utility industry leaned on a three-legged stool of affordability, safety, and reliability to set its priorities. Now the very meaning of that third leg is being rewritten. Extreme weather events, surging demand from electrification and data centers, and the rise of distributed energy resources (DERs) are forcing utilities to rethink what it means to keep the lights on—and at what quality and cost.

Joe Zerdin, Director of Distribution Large Customers, Sustainment, and Technical Services at Hydro One, sees the shift daily. “The core of reliability is still there in terms of indices such as SAIDI,” he said, referencing the industry-standard outage duration metric. “What has become more prevalent is that momentary outages are becoming as impactful, and it’s usually not on a regulatory scoreboard such as SAIDI. There also seems to be a blend from a customer perspective between reliability and power quality events.” Zerdin noted that the industry still lacks a universal measurement for resiliency, making it harder to track progress.

The grid itself is transforming from a one-way delivery system into a dynamic, two-way network. That means deploying advanced distribution management systems (ADMS), integrating customer-side assets, and hardening equipment against unpredictable weather. But according to Zerdin, the real hurdle is not the technology alone. “The biggest challenge is the integration of the multitude of systems in order to work seamlessly together to address capacity, reliability, and resiliency,” he said. “It starts with more integrated planning, acceptance of utilizing customer equipment from an operational and regulatory perspective, and also the scale of the integration. All of these challenges fall under the umbrella of maintaining affordability for all customers.”

Zerdin will outline active initiatives and real-world case studies from Hydro One at the DTECH Reliability & Resiliency conference, August 25-27, 2026, where the focus will be on breaking down silos between utilities and their largest customers to enable that next level of collaboration.

Behind the Rewrite: Integration, Regulation, and Customer Economics

The SAIDI Shortfall and the Resiliency Gap

Traditional reliability metrics like SAIDI (System Average Interruption Duration Index) measure average outage minutes per customer over a year. Zerdin highlights a growing blind spot: momentary outages—power flickers lasting seconds—that SAIDI fails to capture. For commercial and industrial users, even a sub-second interruption can halt sensitive manufacturing lines or data center operations, causing significant costs. Yet these events rarely trigger regulatory penalties. At the same time, there is no industry standard for measuring resiliency—the grid’s ability to withstand and recover from high-impact, low-probability events. This metrics gap means utilities and regulators lack a common yardstick for tracking improvements, leaving investment decisions that affect millions of customers in a data-poor environment.

Hydro One’s Integration Challenge

The push to modernize the distribution grid brings technical and financial complexity. Hydro One, like many large utilities, is working to weave together ADMS, DER management systems, and programs that leverage customer-owned assets such as smart thermostats, batteries, or backup generators. Zerdin’s central point is that integration is not just a software challenge; it demands that these systems work “seamlessly together” during normal operations and extreme events. This requires upfront investment in interoperability planning and testing that can strain capital budgets. The constraint of affordability—already in the spotlight for regulators and consumer advocates—limits how quickly utilities can roll out such upgrades, creating a tension between reliability goals and rate impacts.

Regulatory Hurdles and Customer Collaboration

A significant barrier Zerdin identifies is the need for regulatory frameworks to “accept” the operational use of customer equipment. In many jurisdictions, a utility may not be allowed to control a customer’s battery or generator for grid support without clear tariff and reliability rules. This slows the deployment of cost-effective solutions that could shave peak demand and improve local resilience. Additionally, the traditional utility-customer relationship was one-way. Now, utilities and large commercial and industrial partners must develop a mutual understanding of how their networks interact. Zerdin’s call for stepping outside established silos echoes a broader industry push: only by jointly mapping power flows and outage sensitivities can both sides avoid costly misalignment in a two-way grid.

What the Evolution Means for Utilities and Large Customers

• Supplement SAIDI tracking with momentary outage data. Because Zerdin notes that these events are increasingly impactful yet missing from regulatory scoreboards, utilities should begin logging power quality incidents at the feeder level, especially for large customers with high sensitivity, and share trend data to guide investment.
• Initiate joint planning sessions with top commercial and industrial accounts. Map how each customer’s DERs and backup systems can be integrated for mutual benefit, then develop pilot projects that test the operational and regulatory frameworks Zerdin says must evolve.
• Engage regulators early on customer-asset utilization proposals. Propose new tariff or reliability-performance incentives that allow controlled use of customer-side batteries or generators for grid support, addressing the regulatory acceptance gap directly.
• Audit ADMS-DER interoperability under extreme weather scenarios. The integration of multiple systems is Zerdin’s top challenge; run tabletop drills that simulate simultaneous weather-related outages and DER dispatch to expose data and control gaps before they cause real-world failures.