Enhanced Reliability of Photovoltaic Systems with Energy Storage and Controls

Abstract

PrefaceNow is the time to plan for the integration of significant quantities of distributed renewable energy into the electricity grid. Concerns about climate change, the adoption of state-level renewable portfolio standards and incentives, and accelerated cost reductions are driving steep growth in U.S. renewable energy technologies. The number of distributed solar photovoltaic (PV) installations, in particular, is growing rapidly. As distributed PV and other renewable energy technologies mature, they can provide a significant share of our nation's electricity demand. However, as their market share grows, concerns about potential impacts on the stability and operation of the electricity grid may create barriers to their future expansion.To facilitate more extensive adoption of renewable distributed electric generation, the U.S. Department of Energy launched the Renewable Systems Interconnection (RSI) study during the spring of 2007. This study addresses the technical and analytical challenges that must be addressed to enable high penetration levels of distributed renewable energy technologies. Because integration-related issues at the distribution system are likely to emerge first for PV technology, the RSI study focuses on this area. A key goal of the RSI study is to identify the research and development needed to build the foundation for a high-penetration renewable energy future while enhancing the operation of the electricity grid.The RSI study consists of 15 reports that address a variety of issues related to distributed systems technology development; advanced distribution systems integration; system-level tests and demonstrations; technical and market analysis; resource assessment; and codes, standards, and regulatory implementation. The RSI reports are: Addressing grid-integration issues is a necessary prerequisite for the long-term viability of the distributed renewable energy industry, in general, and the distributed PV industry, in particular. The RSI study is one step on this path. The Department of Energy is also working with stakeholders to develop a research and development plan aimed at making this vision a reality. iv AcknowledgmentsThe authors would like to acknowledge Ray George from NREL for providing insolation and temperature data for regions of the United States. The authors would also like to acknowledge the contribution of Tom Short from EPRI. Tom provided the GE team with detailed reliability data for two utilities in the United States. The project team would also like to thank the following individuals for their contributions to this study:1. Jim McMahon of LBL for appliance data models, start/end time estimation.2. Craig Cornelius for the interaction needed to obtain load modeling data and information.3. Robert Delmerico of GE Global Research for providing data from studies on load modeling in residential communities.4. Lawrence Berkley Labs for providing load shapes for several appliances, distinguishing week and weekend days.5. Patrick G. McElhaney (GE C&I) for providing data on av...

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