The big U.S. solar show, Solar Power International, is coming up next month (Oct 11-14 in Los Angeles), and there are going to be a lot of announcements made on the solar front in the weeks ahead.  The PV inverter market is hot, and well-funded Enphase Energy, the microinverter manufacturer, is starting its volley with the announcement of a fourth-generation integrated microinverter.

I spoke with Enphase co-founder Raghu Belur and newly-hired Chief Marketing Officer Bill Rossi about the new product, some upcoming announcements, and the state of the company.

Firstly, Enphase has shipped more than 400,000 microinverters.  The company is no longer a classic startup but rather a company with a different set of problems challenges, including scaling up and maintaining growth with a focus on manufacturing, sales and execution (which explains the Bill Rossi hire and his Cisco growth pedigree).  A VC colleague recently called Enphase CEO Paul Nahi "an execution machine."

The new Enphase product is a next-generation microinverter that bumps the CEC efficiency from 95 percent to 96 percent in a smaller package and reduces the component count in the Bill of Materials by integrating some IC functions.

But the more important change is the emergence of a new product -- the AC module, or ACM.  Until now, the microinverter has been mounted on the module racking hardware.  But module manufacturer and solar integrator confidence in microinverter architecture has now allowed the the microinverter to migrate to where the junction box used to be.  Module manufacturers and installers had to be convinced that microinverter performance and long-term reliability was unimpeachable.

"Cabling is not sexy," said Belur, but the bottom line for the AC module is a reduction in cabling, installer roof time and Balance of System (BoS) costs.  Belur noted, "The module is now married to the inverter," and continued, "The integration process takes a few seconds," adding that "the path to an ACM is through a microinverter."

In a solar market where PV module cost drops every quarter, cost is also getting scrubbed out of BoS and installation and the ACM is part of that. 

Note that the sales channel will see the microinverter sold by the module manufacturer or as part of the installer's offerings, so partnership is key for any microinverter player, and success in the market is as much a technology play as it is a channel play.

Enphase will have some more announcements on module partners at SPI in October.

A crucial factor to consider in the ACM space is warranty.  It would seem obvious that customers will want the microinverter warranty to match the twenty to twenty-five year warranty of the PV panels themselves.  But not all vendors might be able to make that claim.

Other microinverter and ACM companies to keep your eye on are SolarBridge, Petra Solar, Enecsys and GreenRay.