The Electronic Wind Performance Reporting System (eWPRS) is a publicly accessible database of wind plant performance data in California. The eWPRS provides a simple and convenient interface for accessing data dating back to 1985. It is based on data collected by the California Energy Commission’s Wind Performance Reporting System (WPRS) program. Click here to access the Wind Performance Reporting System data query.

You can also retrieve summary reports prepared by the Energy Commission with the list of links below.

The eWPRS is administered by the California Wind Energy Collaborative to facilitate the research and analyses needed for California to reach its renewable energy goals. If you have any questions, please contact ewprs@cwec.ucdavis.edu.

WPRS Overview

California law requires the California Energy Commission to serve as a central repository in State government to collect and disseminate information on energy supplies. Since January 1985, WPRS regulations have required all California wind operators with projects rated at 100 kW or more to provide quarterly wind performance reports if they sold electricity to a power purchaser (utility). WPRS reports filed by operators included information such as actual energy production and related project information. In addition, all California power purchasers are required to file quarterly reports documenting power purchases from wind operators. The Commission compiles, evaluates these data, and documents findings in annual reports on wind industry performance in California. Annual WPRS reports can be downloaded below.

Legislative History of the WPRS

The Commission Wind Program was initiated in 1977 and later expanded in 1978 with the passage of California AB-2976 authored by Assemblyman Henry Mello. The Mello bill required the Commission to implement a State wind energy program to expedite the commercialization of utility-scale wind turbines. The Commission was responsible for assessing wind resources throughout California, operating a public wind information center, testing wind turbines, and conducting research to support development of large-scale prototype wind turbines.

When the industry began exponential growth in 1981, the Commission and the American Wind Energy Association (AWEA) recognized the need for performance and other technology-related information. Subsequent efforts by these two organizations led to adoption of Wind Project Performance Reporting System regulations in 1984.

Motivations for WPRS Implementation

WPRS regulations were instituted for many reasons. First, the industry, investors, financial community, and government agencies need actual performance data to better evaluate the status of wind technology and necessary improvements. Second, wind performance data provide a better understanding of the role wind resources can play in meeting California’s energy needs. Last, the WPRS provides the public with an open and objective source of information about wind energy technologies.

Information Provided by WPRS Summary Reports

The WPRS reports include the following information for wind projects in California rated at 100 kilowatts (kW) or more, that sell electricity to a power purchaser: turbine manufacturers, model numbers, rotor diameter and kW ratings; the number of cumulative and new turbines installed; the projected output per turbine (no longer reported after 1995); the output for each turbine model; and the output for the entire project. The reports are compiled from periodic reports submitted by project operators and public utilities. The Commission staff uses this WPRS data to analyze wind project performance and industry production and capacity trends. The reports also contain data summary tables reflecting performance statewide and by resource area; turbine size, type and origin; manufacturer; and project operator.

Summary Reports

2002 – 2003
2000 – 2001
1996 – 1999


Limitations of the WPRS

WPRS reports do not provide information on every wind energy project in California. The absence of a project from the WPRS typically indicates that the project is not selling any power or is rated less than 100 kW. Non-operating wind projects are not required to report to the Commission. Other unreported capacity includes turbines that do not produce electricity for sale, such as turbines installed by utilities, government organizations and research facilities. Additional unreported capacity results when operators fail to file. Installed capacity for these operators cannot be confirmed and only kWh production verified from utility reports is included in WPRS reports.

Data reported by qualifying facilities and utilities and/or other sources may not compare directly because the wind industry still does not employ a standardized turbine rating system. Turbines are tested under different conditions and rated at widely varying wind speed specifications.

Operator or manufacturer performance may not be accurately represented in the report when old and new turbine data are grouped together. Analysis of wind data reported since 1985 confirms that newer equipment typically performs more efficiently and reliably than older equipment.

Performance data contained in WPRS reports do not reflect other important variables that should be considered. These variables include cost per kilowatt, operation and maintenance costs, durability of the system, and quality of a site’s wind resource.