SolarCity installed nearly a third of all U.S. residential PV in the third quarter of 2013, installing almost four times as much as its closest competitor, Vivint Solar, according to GTM Research's US PV Leaderboard, released today.

The leaders in Q3 residential solar installs in the United States:

SolarCity

Vivint

Verengo

REC Solar

Real Goods Solar

With a newfound ability to raise public capital and a mandate to continue its rapid expansion, SolarCity remained aggressive throughout 2013. "In addition to a steadily growing market share, the company made a bevy of moves over the course of the year, ranging from the first securitized distributed solar deal to the acquisitions of Paramount Solar and Zep Solar," said Shayle Kann, Senior Vice President, GTM Research. "SolarCity's 2014 guidance suggests another rapid year of growth, barring bottlenecks in component costs, project finance or regulation."

SolarCity's diverse sales strategies have played a major role in the company's ability to capture such a large share of the residential market. Solar analyst Nicole Litvak cited its key partnerships with companies like Home Depot, Honda, and Viridian Energy to tap new sources of customers. "The installer has been quick to enter and dominate new residential growth markets such as New York and Connecticut," added Litvak.

While SolarCity is dominant in stalwart solar markets like California and Arizona, it doesn't top the Leaderboard in all states. Vivint has led Massachusetts all year, and New Jersey-based companies Roof Diagnostics and Trinity Solar Power beat out SolarCity in the Garden State in Q3.

"SolarCity's market share is likely to continue growing into 2014, but the addressable market is large enough to allow for growth among major competitors like Vivint, local installers, and new players in the residential solar industry," said Litvak.

The numbers are still pouring in, but GTM Research estimates that installers added 753 megawatts of residential PV in 2013, according to the U.S. Solar Market Insight report.

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Leveraging exclusive relationships with individual state-level rebate agencies and advocacy groups, GTM Research has been able to combine detailed project-level data with publicly available information to produce the most comprehensive market share estimates available for the U.S. solar market in its U.S. PV Leaderboard. This product provides quarterly and national market-share estimates for installers and module suppliers, as well as state-by-state breakdowns for California, New Jersey, Arizona, Maryland, Massachusetts, Connecticut, New York, Ohio and New Mexico. Combined, the data from these states represents over 60 percent of the installed solar capacity in the U.S.