Wind Performance Report Summary Program Scope

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.

Efforts Leading to the Wind Project Performance Reporting System

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 (WPRS) regulations in 1984.

Reasons for Wind Performance Report Summary Regulations

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. Lastly, the WPRS provides the public with an open and objective source of information about wind energy technologies. Before federal tax credits expired in 1985, project financing was primarily venture capital from private investors willing to take a substantial risk on the technology due to available tax benefits. Since the tax credits expired, wind projects have focused on revenues from power sales and placed greater reliance on conventional project financing from institutional lenders and foreign investors. WPRS data also were needed to establish performance credibility with these new sources of financing.
Information Provided by Wind Performance Report 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 report is compiled from quarterly 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 Annual Report also contains data summary tables reflecting performance statewide and by resource area; turbine size, type and origin; manufacturer; and project operator. Note that totals expressed in tables and figures may not equal 100 percent due to rounding.

Since 1985, the Commission has collected, documented and evaluated data submitted by operators and utilities in compliance with WPRS regulations. Extensive empirical data collected and disseminated by the Commission are used by industry, utility, investor, manufacturer, government, and research and development groups to evaluate the performance and relative benefits of wind technology.
Information Not Provided by Wind Performance Report Summary Reports

WPRS reports do not provide information on every wind energy project in California. The absence of a project from WPRS reports 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. In addition, WPRS reports cannot account for the impact turbine age has on performance because turbines are often reported in groups combining old and new machines.

Considerations and Limitations Using Wind Performance Report Summary Data

Although many valuable observations about California’s wind industry can be drawn from WPRS data, it is important to recognize some major limitations:

   1. While the Commission collects and reports WPRS wind data in annual reports, a complete industry evaluation requires consideration of collective data from several years. This is because the available wind resource varies from year to year depending on weather conditions.
   2. 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 miles-per-hour specifications. Whenever standard formulation is used to compute values, the equations and inputs are described.
   3. 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.
   4. 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 the site’s wind resource.

Please direct any questions or comments about this website and electronically accessing the WPRS data to ewprs@wind.ucdavis.edu.

This eWPRS website is maintained by the California Wind Energy Collaborative.