The Grid System Technologies Advanced Research Team (GridSTART) of the Hawaii Natural Energy Institute (HNEI), University of Hawaii, in collaboration with Maui Electric Company (MECO) and with funding from the U.S. Office of Naval Research (ONR), has proposed and installed a practical, inexpensive and effective solution to address the integration of very high levels of rooftop PV and the occasional excess of intermittent solar energy produced in aggregate by the PV systems on the Island of Moloka‘i. In addition to serving as a means to efficiently balance total system generation and demand during periods of excess solar energy production relative to island power demand, the asset also serves as a grid stabilizing “safety valve” to rapidly absorb excess energy during unplanned system disruptions, such as a sudden loss of generation on the grid.
This unique solution features a 750 kW resistive dynamic load bank connected to the island’s electrical grid. The load bank is operated both autonomously using advanced controls according to predefined conditions and manually at MECO operator discretion from the utility control room. The addition of this load bank on the grid has allowed MECO to release a hold (in place since 2015) on the interconnection queue for rooftop PV, allowing the addition of approximately 725 kW of new rooftop systems. The island of Moloka‘i, with a daytime system demand that can dip as low as 3.3 MW, already has approximately 2.3 MW of rooftop PV in operation.
This load bank provides a reliable means to prevent baseload diesel generation on Moloka‘i from going below its minimum reliable operating level (risking unit trip and island-wide blackout) due to excess rooftop PV energy production on the island. GridSTART is continuing its work with MECO to develop and test the capabilities of the load bank to provide additional benefits such as frequency regulation and down reserves in coordination with a 2 MW battery previously installed and under test in further HNEI-MECO collaboration on Moloka‘i.
More information regarding this project:
› HNEI Press Release: Molokai Dynamic Load Bank (PDF)
› UH News Press Release: https://www.hawaii.edu/news/2019/07/12/manoa-hnei-meco-photovoltaic/
Additional articles: The Molokai Dispatch, Utility Dive, Civil Beat
