Distributed Energy Resource (DER)

A distributed energy resource, or DER, is a generation, storage, or controllable demand asset connected at or near the distribution network rather than at bulk transmission level. DER is a broad term that covers both devices that inject power and flexible resources that can change consumption in response to system needs.

DER growth is changing how distribution systems are planned and operated because power no longer moves only from transmission to end users. High DER penetration can improve flexibility and resilience, but it also creates new challenges for voltage control, protection, and network visibility.

Key Aspects of Distributed Energy Resources:

• Broad Technology Scope: DERs include rooftop solar, behind-the-meter batteries, community storage, small wind, fuel cells, combined heat and power, electric vehicles, and controllable loads. The term refers to connection level and operating role rather than to one specific technology.
• Bidirectional Power Flow: Large DER uptake can reverse traditional feeder power flow during light-load, high-generation periods. This affects voltage rise, thermal loading, transformer utilization, and protection behavior.
• Operational Opportunity: DERs can provide energy, peak shaving, reactive support, fast frequency response, and local resilience if properly controlled. Aggregation allows many small units to act as a coordinated system resource.
• Integration Challenge: Distribution operators need better forecasting, observability, and control as DER penetration increases. Hosting-capacity limits, connection queues, and dynamic operating envelopes become more important.
• Market and Grid Role: When aggregated, DERs can participate in balancing, capacity, and ancillary-service markets through VPP-style platforms. Their system value depends heavily on control quality, telemetry, and regulatory design.