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NREL and Partners Demonstrate First-of-a-Kind Use of Utility-Scale PV for Ancillary Services

January 28, 2016

While utility-scale solar photovoltaic (PV) power plants are being increasingly deployed across the country, some believe higher penetrations of PV technologies may potentially impact grid reliability due to the variability of the solar energy resource-meaning utilities may severely limit PV installations or increase assigned integration costs when considering a least-cost portfolio. Deployment of utility-scale, "grid-friendly" PV power plants that incorporate advanced capabilities to support grid stability and reliability is essential for the large-scale integration of PV generation into the electric power grid, among other technical requirements, as a means to mitigate the impact of said variability on the electric system.

To help address these utility concerns, NREL collaborated with AES, the Puerto Rico Electric Power Authority, First Solar, and the Electric Reliability Council of Texas to conduct a demonstration project on two utility-scale PV plants in Puerto Rico and Texas to test their ability to provide important grid ancillary services. Testing was completed on two 20+ MW plants that demonstrated the ability of PV power plants to provide various types of new grid-friendly controls. Funding for this project was provided by the Energy Department's SunShot Initiative.

This demonstration showed how active power controls can leverage PV's value from being simply a variable energy resource to providing additional ancillary services that range from spinning reserves, load following, ramping, frequency response, variability smoothing and frequency regulation, to power quality. Specifically, the tests conducted included variability smoothing through automatic generation control, frequency regulation for fast response and droop response, and power quality.

The bottom line for utilities? If PV-generated power can offer a supportive product that benefits the power system and is economic for PV power plant owners and customers, this functionality should be recognized and encouraged.

More information on the project and detailed results can be found in the recently released report Advanced Grid-Friendly Controls Demonstration Project for Utility-Scale PV Power Plants.