SolarBridge draws $19M to push solar microinverters

Here’s another sign that a new class of solar inverters are cementing their hold in the market: SolarBridge Technologies announced Monday that it has raised $19 million to expand the sales and manufacturing of its microinverters.

Microinverters are miniature versions of conventional central inverters that are necessary for converting the direct current generated by solar panels to alternating current for feeding the grid or to be used onsite. Instead of matching a central inverter to a dozen panels at a time, each microinverter serves one panel. This design allows the microinverters to calculate and adjust the optimal energy output of each solar panel and prevents poor-performing panels from affecting the power output of the best-performing ones.

A central inverter will do the same calculations and optimization for the dozen solar panels, but the poor-performing panels, such as those in the shade or covered in dirt and debris, will lower the results and therefore the AC power output of the central inverter. But central inverters are cheaper than microinverters and have more field data to show their reliability.

Austin-based SolarBridge is among a group of startups that are commercializing microinverters and butting heads against central inverter manufacturers who have to date dominated the market. Some central inverter makers are plotting their own entry into the microinverter space. Power-One already introduced a microinverter last month. SMA Solar Technology says it will do so soon enough.

After some product development delays, SolarBridge said last month it had begun producing microinverters in volumes. Company CEO, Ron Van Dell, told me then that the company decided to spend more time designing microinverters that can last as long as solar panels, which typically carry a 20-25 year warranty. SolarBridge is keen on promoting what is called the “AC solar panels,” which come pre-assembled with microinverters. Combining them in the factory rather than putting them together at a project site should cut installation costs. One big challenge is to line up solar panel makers who are willing to take a chance at offering this new type of product.

Van Dell wasn’t willing to say which solar panel makers will roll out AC panels with SolarBridge’s gear, except that the products will show up this summer. In the company’s funding announcement Monday, it hinted at having lined up a solar panel maker as a new investor. SolarBridge declined to name the investors in the C round except to say that some previous investors also put up money this time. Previous investors included Rho Ventures, Battery Ventures and Texas Emerging Technology Fund. SolarBridge plans to use the new fund to expand production and marketing. The company has hired Celestica to make its microinverters in China. Overall, SolarBridge has raised roughly$46 million to date.

The biggest microinverter player remains Enphase Energy, which last week announced it will go public. The northern California company has shipped more than 750,000 microinverters since its initial product launch in mid 2008. The company has grown its revenues but still posts losses (here is our detailed look at the $100 million IPO filing).

Installations with Enphase’s microinverters have popped up in North America, and the company has opened offices in Europe this year to tackle that market. It recently launched the third-generation technology to broaden the use of its microinverters for different types of solar panels.

Enphase also has strengthened the warranty of its microinverters to 25 years in order to promote its microinverters as a good match for AC panels. In fact, AC panels with its microinverters will show up in the first half of 2012, the company said. Enphase hasn’t said which solar panel makers will sell the AC panels.

Enphase has made microinverters a viable alternative to central inverters. Competition is intensifying as other microinverter makers line up money to better compete. SolarBridge isn’t alone in securing new funding lately. U.K.-based Enecsys, said last month it had raised $41 million to expand its reach.

Photo courtesy of SolarBridge Technologies