Smoothing and Shifting Pv – Applying Energy Storage to Enhance the Benefits of Renewable Energy

Renewables and specifically photovoltaics (PV) are playing an ever increasing role in the resource mix for utilities across the nation. These resources pose new integration challenges compared to traditional generation. Higher penetrations of PV can lead to voltage instability due to intermittencies related to cloud cover and the output of PV is generally noncoincident to utility system load peaks. One prospective solution to this intermittency is battery energy storage, designed and controlled to smooth and shift PV output. At a recently commissioned project by the Public Service Co. of New Mexico (PNM), advanced lead acid batteries are utilized to shape the variable output of a 500kW PV resource to more beneficially impact the utility grid This ARRA/DOE funded Smart Grid Storage Project is testing and optimizing both smoothing and shifting capabilities of the batteries and their ability to create a dispatchable, firm and reliable renewable resource. As part of this project, detailed computer models of the local utility grid were first developed to further understand integration of the batteries and PV. The results of actual field operation, combined with the underlying models are presenting a clear path in terms of optimizing battery size, and control algorithms, as well as offering a benchmark for measuring the benefits of battery storage. These results, coupled with the optimization capabilities of the models will lend the industry key results that are translatable to a variety of PV installations.