PETALUMA -- Enphase Energy Inc. (NASDAQ: ENPH) launched its fourth-generation solar electricity inverter Tuesday at the Intersolar North America expo in San Francisco.

[caption id="attachment_77033" align="alignright" width="315"] The newest Enphase microinverter, the M250, is tougher, more powerful and more efficient than previous models.[/caption]

The new M250 model is tougher, more efficient, more powerful and its software interface more intuitive than ever, according to Enphase Chief Executive Officer Paul Nahi.

"Our first model, released in 2008, was 125 watts and 94 percent efficient. Now we're up to 250 watts and 96-and-a-half percent efficiency, and we continue to improve," he said. "Also the M250 model has no grounding cable, adding greatly to ease of installation."

The 5-year-old maker of residential and commercial solar power inverter systems has now shipped more than 3 million microinverters worldwide and leads the industry in residential installations in the Americas, according to industry data published Monday by IHS Research in its PV Inverter World Market Report 2013.

"We're very proud of that data," said Mr. Nahi. "I can't think of another company in any industry with the amount of market share -- 53.5 percent -- we've gained in so short a time period."

[caption id="attachment_77032" align="alignleft" width="250"]

Nicolas Carter of NPC Solar attends training for the M250 microinverter at Intersolar North America in San Francisco.[/caption]

The Enphase microinvervters convert direct-current (DC) electricity to alternating-current (AC) electricity at each solar module level, instead of at a central inverter. That distributes the power source as well as optimizing the output of each solar panel. Problems due to shade from other buildings or trees are largely mitigated. The systems include a web-enabled software interface with tools for both residential owners and managers of large commercial installations.

Enphase is aggressively building out its global market, opening offices in six countries. The U.S. has 15 percent of the global solar market. "We'd like to make serious inroads on the remaining 85 percent,' said Mr. Nahi, "and we're doing well despite heavy competition in the more mature European and Australian markets."

The company had revenues of $217 million in 2012. It has not yet reached profitability, although Mr. Nahi described himself as "very comfortable with our current path." Enphase employs about 400 in its Petaluma headquarters.