Recent weather events have proven that a single storm can cause billions of dollars of damage to the electrical power grid as well as significant power outage-related costs. As a result, utilities across the United States are working to make their microgrid services more resilient. This alone is a challenge, but some utilities also face state-level pressure to improve the reliability of their systems. In 2014, North Carolina became the first state in the Southeast to adopt a Renewable Energy and Energy Efficiency Portfolio Standard (REPS), driving utilities in that state to add more renewable resources to their systems . This resulted in North Carolina ranking fourth in the United States in total installed solar capacity with 397 MW of solar installations and with the second-fastest growth of solar capacity nationwide. The economic impact of weather events and this drive to add renewable resources led the North Carolina utility Duke Energy to develop its own solar-powered microgrid demonstration project.
Since 2006, the Duke Energy McAlpine Creek Substation in Charlotte, North Carolina has been a test bed for smart grid and renewable generation technology. The area just outside the substation fence houses a 50 kW photovoltaic (PV) installation as well as a 240 kW, 500 kWh battery energy storage system (BESS). These two assets are connected in parallel to import and export energy to McAlpine Creek Circuit 2414 at the substation.
Located adjacent to the substation property is the City of Charlotte Fire Station 24 (FS24). Duke Energy and the City of Charlotte agreed to partner in a mutually beneficial technology proof-of-concept project. FS24 was interested in having the PV installation and the BESS combined to provide backup generation services to the fire station. Duke Energy was interested in using the BESS for grid support services when it was grid-connected.