California-based Pacific Gas and Electric (PG&E) has topped the list of US utilities that added most new solar capacity to their systems in 2013.

According to the annual ranking published by industry body Solar Electric Power Association (SEPA) PG&E installed 1,471MW of solar in 2013, well over double that of its nearest rival, San Diego Gas & Electric, which added 643MW.

This will be sixth year PG&E has topped the list. All of the top three utilities were from the western half of the US, with Arizona Public Service taking the third slot after SDG&E with 417MW.

The apparent role of some utilities in undermining the penetration of solar by seeking to water down net metering policies has become a source of growing controversy in the US.

Indeed Arizona Public Service’s position near the top of the SEPA table will be a source of some irony for pro-net metering campaigners, as the utility became embroiled last year in claims it had bankrolled anti-solar campaigns. The utility eventually succeeded in its bid to have a charge levied on solar net metering customers, but the negligible size of the charge meant the pro-solar camp claimed the victory.

PGE&E, too, has been accused of fomenting anti-net metering sentiment.

But SEPA said America’s utilities were nonetheless responsible for 82% of new solar capacity in 2013, up from 72% the year before.

Six of the ten utilities previously ranked in 2012, with Duke Energy Progress, National Grid, Public Service Electric and Gas and Georgia Power all newcomers to this year’s list.

SEPA also measures the top utilities in terms of the number of customers they serve relative to the solar megawatts they install.

By this count, Massachusetts-based utility Sterling Municipal Light Department is the leader, installing 831W per customer last year. This was almost double its nearest rival, SDG&E.

“We are thrilled to see milestones surpassed and barriers broken from coast to coast," said Julia Hamm, president and CEO of SEPA. "It's truly inspiring to see utility partners and their consumer communities rally around implementing solar programs that are changing the nature of our national energy portfolio."