DERs

Distributed energy resources (DERs) are small- to medium-scale electricity generation or storage technologies located close to load centers that can be controlled to maintain or enhance grid stability. DERs include generation such as rooftop solar photovoltaic systems and small wind turbines, energy storage such as batteries and flywheels, demand-side resources like smart thermostats and industrial load controls, and electric vehicles and other flexible loads that can be curtailed or discharged when needed. They may operate in isolation or be coordinated as a network to provide services to the distribution system, the transmission system, or both.

DERs can be connected at customer sites or within microgrids and can participate in energy markets through aggregation. When coordinated, they provide services such as voltage regulation, frequency response, peak shaving, energy arbitrage, and backup power. Tools such as distributed energy resource management systems (DERMS) and virtual power plants (VPPs) are used to monitor, control, and optimize DER performance. International and national standards and grid codes, including interconnection standards like IEEE 1547, guide safe and reliable operation and interoperability.

Benefits of DERs include improved grid resilience, reduced transmission losses, deferred infrastructure investments, and enhanced customer choice. They can also introduce challenges such as variability and intermittency, protection coordination, cybersecurity, data privacy, and the need for appropriate market or tariff structures and regulatory frameworks to fairly value services provided by DERs. Effective integration typically requires coordinated planning, reliable communication, and clear roles for utilities, regulators, aggregators, and customers.