REVISED 1/2/2019. SEE UPDATE LINK BELOW. This database contains unit cost information for different components that may be used to integrate distributed photovotaic D-PV systems onto distribution systems. Some of these upgrades and costs may also apply to integration of other distributed energy resources DER. Which components are required and how many of each is system-specific and should be determined by analyzing the effects of distributed PV at a given penetration level on the circuit of interest in combination with engineering assessments on the efficacy of different solutions to increase the ability of the circuit to host additional PV as desired. The current state of the distribution system should always be considered in these types of analysis. The data in this database was collected from a variety of utilities PV developers technology vendors and published research reports. Where possible we have included information on the source of each data point and relevant notes. In some cases where data provided is sensitive or proprietary we were not able to specify the source but provide other information that may be useful to the user e.g. year location where equipment was installed. NREL has carefully reviewed these sources prior to inclusion in this database. Additional information about the database data sources and assumptions is included in the Unit_cost_database_guide.doc file included in this submission. This guide provides important information on what costs are included in each entry. Please refer to this guide before using the unit cost database for any purpose.