Enphase Energy has raised $15 million to boost its production of its micro-inverters, which convert direct current from individualsolarpanels into alternating current for the electric grid.

The Petaluma, Calif., startup launched its first product in June and joined both long-term and startup companies angling for a piece of the growing solar market (see Enphase Energy Seeks New Converts).

At the time of the product launch, a Frost & Sullivan analyst pointed out that the company would need to raise more money to keep its momentum going. The two-year-old Enphase had previously raised a total of $6.5 million.

Enphase isn't only company selling the micro-inverters, which also monitor panel performance. The company is selling a package that includes a broadband gateway for sending the performance data to an Enphase-run service data for analysis. Customers can view the performance data over a Website.

In addition to charging customers for the hardware, Enphase also collects a monthly fee for the monitoring service, which evaluates each panel's performance every 10 minutes and alerts both Enphase staff and the customers of any problems.

Enphase is selling its products and services through installers and distributors such as AEE Solar, DC Power Systems, Focused Energy, Solar Depot and SunWize Technologies Inc.

In most systems, just one large centralized inverter converts power from a whole array of panels. Enphase instead puts small inverters on each solar panels. 

Enphase CEO Paul Nahi has previously said that his company's product can collect more thorough data and identify problems more quickly than centralized inverters, a feature that could enable solar array owners to fix problems promptly and improve their energy output.

Enphase wants to do it all – develop hardware, software and services. But safeguarding customers' data and providing good customer service could pose challenges for the startup. The company also competes with a slew of inverter makers, including Xantrex Technology, SMA Technologie, Kaco Solar, Fronius International and Conergy.

Enphase is targeting residential and business customers. The company would have to retool its inverter design to sell to utilities.

Investors for the round include newcomer RockPort Capital Partners. Other investors include Third Point Ventures and Applied Ventures, the investment arm of Applied Materials, which develops solar-panel-manufacturing equipment.