One important component is the oft-overlooked inverter. The devices convert power generated by solar cells into usable electricity and optimize a system’s efficiency. Enphase Energy, which has been tinkering with improving inverters for commercial and residential use since 2006, on Tuesday said it raised $15 million in a new round of funding led by RockPort Capital partners.

Solar systems today use centralized inverters—many panels feeding into a single large one. By contrast, Enphase makes so-called micro-inverters that are small enough so that each solar panel gets its own. The result, says the company, is that solar systems are cheaper, more robust, and more efficient, since each panel performs independently within the array. The Petaluma, California, company says its micro-inverters can increase energy harvest by up to 25 percent.

But some skeptics have questioned the company’s claims of improved efficiencies by replacing one large inverter with numerous small ones, thereby increasing the number of parts and connections in the system.

If the company’s claims are true, the solar energy sector would benefit, said David Kurzman, senior vice president of Panel Intelligence. But he cautioned that solar panels represent the bulk of overall system cost—about two-thirds according to Panel Intelligence estimates. That means the benefits of any reduction in the cost of inverters will still be relatively small compared with progress among solar cells.

Enphase’s micro-inverters also transmit data about their performance to a “communications gateway” with a broadband Internet connection. The company automatically collects and analyzes the data and suggests solutions to correct any problems detected.