Grid stability issues were introduced by the wide distribution of 1-2 megawatt solar
photovoltaic systems on educational and commercial campuses and the use of the utility grid to store energy produced by these systems in excess of campus needs. To address these issues, the Las Positas Microgrid Project provides a model for campus grids to include on-site storage with upgraded smart grid control systems. The Las Positas Microgrid project installed a 200 kilowatt, 1,000 kilowatt-hour battery energy storage system to the 21.7 kilovolt grid at Las Positas College. The new storage system included predictive energy management applications to reduce peak utility power demands and reduce energy use in response to demand response signals. The new control systems integrate with the existing campus energy control systems to manage existing energy storage, generation, and consumption assets (including a 3,200 ton/hour thermal ice storage system); 100 kilowatts of light-emitting diode lighting; 2,350 kilowatts of photovoltaic solar generation; and heating, ventilation, and air conditioning systems across the campus. The project included installation of a UniEnergy Technologies ReFlex™ vanadium redox flow battery, an energy storage system that pumps electrolyte through stacks of electrochemical cells. The system showed it could reduce multiple power peaks during a four-hour evening period of maximum energy demand and store excess solar generation during the day. The $1.8 million project is projected to reduce the college’s energy cost by $120,000 a year with potential for an additional $10,000 annually from demand response participation.
