Rho Ventures led a $15M round B along with existing investor Battery Ventures in microinverter startup SolarBridge.  The company has raised more than $27 million to date.

SolarBridge builds microinverters for PV installations and they differentiate themselves with a focus on enabling module manufacturers to build integrated alternating current photovoltaic (ACPV) modules.

Greentech Media has explored the advantages (and disadvantages) of the innovative microinverter and DC-boost architectures since these startups were first funded with a brief market analysis here.  Microinverters and DC-boost architectures allow for improved energy harvest, easier system design, panel upgrades, better monitoring and the potential for higher reliability and lower LCOE (levelized cost of energy). 

I spoke with SolarBridge's CEO, Ron Van Dell, on Friday.

Van Dell said the objectives for the Round B "were pretty straightforward -- to take the firm, in runway terms, to cash-flow positive."  He said that it was an up-round, done at an increased valuation from the A round (something that didn't happen a lot in 2009).

SolarBridge is not selling their inverters to integrators and installers, but rather is going to market at the OEM level through "strategic partnerships with top-ten module companies."  The SolarBridge microinverter is integrated onto the solar panel itself, not mounted on the rack.  This type of configuration means that the inverter must have as long a lifetime and as long a guarantee as the PV module itself.  To this end, SolarBridge is backing their product with a 25-year warranty.  The firm expects to launch later this year, with production volumes shipping in the fourth quarter.

The firm claims that their microinverter provides an opportunity for solar module manufacturers to eliminate some of their production costs by removing the junction box and bypass diodes.

Jason Matlof of Battery Ventures had this to say: "Our original seed investment in SolarBridge was based upon a strong belief that power electronics in residential PV systems would eventually become integral to the module. We know that the module companys' reliability requirements are extremely demanding, and SolarBridge has the only design that is known to deliver a 25-year warranty.  That really excites us."

Inverters have traditionally been the weak reliability link in a solar installation. The LCOE of the system is heavily penalized if the inverter has to be replaced every five to ten years.  Reliability strides by SolarBridge and other vendors are significantly improving that math.