Solar Electric Power Association (SEPA) has announced Top Ten rankings that reveal which utilities in the United States had the most solar electricity integrated into their energy mix as of the end of 2007. The rankings are based on information provided through a survey of utilities and independent research.

"Based on recent announcements and internal discussions with utilities, SEPA anticipates that utilities will quickly become the largest and one of the most important customers for the solar industry," said Julia Hamm, SEPA executive director. "Whether solar electric systems are developed by utilities, their customers, or solar companies, the utilities' proactive engagement with emerging solar technologies is important to the solar industry as a whole. This market survey and resulting rankings provide a baseline against which increased utility activity can be measured in the future."

For total solar electric capacity by megawatt (MW), Southern California Edison (CA) takes top honors as the most solar integrated utility with the most overall solar capacity (MW) and solar capacity per customer (MW/customer). Southern California Edison's long-standing contracts with the SEGS concentrating solar thermal (CST) plants drive its large number of solar megawatts. However, with a number of recent large-scale CST announcements by several other utilities, Southern California Edison's top ranking may no longer hold once these new plants are constructed.

In addition to overall rankings, additional Top Ten lists were released based on the amount of solar electricity interconnected to the utility in two different configurations: customer side of the meter and utility side of the meter.

On the customer side of the meter, Pacific Gas & Electric (CA) took the honors for both the largest amount of overall solar capacity and the highest MW per customer, but the latter category is in striking distance for several public power utilities. On the utility side of the meter, Southern California Edison is the highest ranked utility both for overall MW as well as MW per customer, which drove its number one total ranking.

The list diversifies when you dive down further into the data and differentiate utility types. On the customer side of the meter for public power utilities, Los Angeles Department of Water & Power (CA) is the most solar integrated in overall capacity, while Kauai Island Utility Cooperative (HI) has the highest capacity per customer.

California-with its long-standing policies for solar market development-represents the majority of the highest rankings, but utilities in Arizona, Colorado, Hawaii, Illinois, Nevada, New Jersey, New York, Texas, Washington and Wisconsin also make the top ten in many categories. Solar markets are expanding rapidly beyond California and when standardized by the number of customers, interesting results will continue to emerge in the coming years. Next year's survey and report will be based on 2008 data and will be published in early 2009. It will no doubt show a reordering of many of these rankings as the solar markets change.

In the last year, U.S. electric utilities' engagement with grid-connected solar electricity increased significantly, with major photovoltaic (PV) and concentrating solar thermal (CST) announcements by utilities, their customers, and third-party solar developers. Utilities have traditionally operated as a solar facilitator, integrating customer developed projects. However, recently there have been several announcements by utilities of new entrepreneurial ideas that provide fresh solutions to regulatory, customer and internal issues.

"These top ten rankings highlight solar-leading utilities that have put significant efforts into facilitating what have traditionally been customer-based solar solutions," says Mike Taylor, SEPA director of research. "What has become apparent however is that over the next few years, there will be an unprecedented level of new utility engagement in the solar industry that develops both centralized and distributed systems in new and unique ways. Several U.S. utilities, some of whom aren't in these rankings yet, are positioning themselves to be the solar industries largest and most innovative customers."