The utility is ahead of its counterparts in both overall solar energy capacity per megawatt and per customer, the study found (PDF). Further north, Pacific Gas & Electric is in front in terms of overall solar capacity and megawatts per customer.
The nonprofit solar association compiled the rankings from data collected from 50 utilities this spring. It projected growth in U.S. solar electricity, particularly photovoltaics, to expand to 600 megawatts in 2012 from 150 megawatts last year.
Southern California Edison came out on top largely due to its interest in large, concentrating solar thermal projects, such as a 245 megawatt agreement with eSolar. And it's working to build 250 megawatts of solar panels across 65 million square feet of rooftops.
However, concentrating solar thermal projects underway by other electricity providers could dethrone the southern California utility from its top spot, the report predicted.
Golden State utilities may be the earliest solar adopters but others in the west, mid-west and mid-Atlantic regions are also increasingly embracing renewables, according to the study.
In its forecast, 4,600 megawatts of concentrating solar systems will be planned nationwide within the next eight years, at least 600 megawatts of which won't come from sprawling solar farms.
For instance, initiatives to encourage solar adoption by homeowners and businesses are coming from Duke Energy, Long Island Power Authority, San Diego Gas & Electric, and Southern California Edison.
State renewable energy portfolio standards will help to advance adoption of big solar installations, but progress will stall if federal tax credits, set to expire at the end of the year, aren't extended, said Mike Taylor, author of the report, said in a conference call.
"We're hitting some new momentum with new business models but this tax credit uncertainty is potentially holding things back and creating some friction in the system," added Taylor, the association's research director. "A lot of utilities are waiting in the wings to see what's happening. Some are jumping ahead of the game because they want to be the first movers."
By his group's estimation, other states making inroads with solar power include Arizona, Colorado, Hawaii, Illinois, Nevada, New Jersey, New York, Texas, Washington and Wisconsin.