Microgrid
A microgrid is a local electric system that can operate with the main grid or disconnect and run on its own. It combines loads, controls, generation, storage, and protection equipment within a defined electrical boundary.
What a microgrid is
A microgrid is a small, controllable electric grid with a defined boundary. It serves local loads such as buildings, campuses, neighborhoods, military bases, hospitals, ports, or remote communities. The key idea is not size alone, but coordinated control of local power sources, storage, and demand.
Connected and islanded modes
Most microgrids normally operate while connected to the main utility grid. If the larger grid fails or the microgrid is intentionally separated, controls can open a switch at the point of common coupling and run the local system in islanded mode. Reconnection must be synchronized carefully so equipment and workers stay safe.
Distributed energy resources
Microgrids are built from distributed energy resources, often shortened to DERs. These can include solar photovoltaics, batteries, diesel or natural-gas generators, wind turbines, fuel cells, controllable loads, electric vehicles, and combined heat and power systems. The best mix depends on the site's goals and constraints.
Controls and protection
A microgrid needs controls that balance supply and demand moment by moment, maintain voltage and frequency, decide when to charge batteries, and prioritize critical loads during outages. Protection equipment must detect faults and isolate problems even when power flows in unusual directions from many small sources.
Resilience and critical loads
Hospitals, emergency shelters, water systems, data centers, airports, and military sites may use microgrids so essential services can continue through wider outages. A design often separates critical loads from noncritical loads, then sizes generation and storage for the outage duration that planners care about.
Remote and community systems
In remote areas, islands, tribal communities, and rural settlements, a microgrid may provide electricity where long transmission lines are expensive or unreliable. These systems can reduce fuel deliveries when they add solar, wind, batteries, or other local resources, but they still need skilled operation and maintenance.
Economics and tradeoffs
Microgrids can reduce outage costs, manage demand charges, support local renewables, and provide grid services. They can also be expensive and complex. The business case depends on fuel prices, outage risk, tariffs, incentives, interconnection rules, maintenance, cybersecurity, and the value placed on resilience.
Cybersecurity and coordination
Because microgrids depend on sensors, communications, inverters, relays, controllers, and software, cybersecurity and interoperability matter. Operators need clear rules for who controls the system, how it coordinates with the utility, and what happens during emergencies, maintenance, black starts, and reconnection.
Why it matters
Microgrids are one way to make electric systems more local, flexible, and resilient. They do not replace the wider grid, but they can give communities and critical facilities more control over reliability while integrating solar, storage, fuel cells, and other distributed energy resources.