Micro Inverters: Working Independently, Generating Power Collectively

September 11, 2008 – Vol.13 No.25

MICRO INVERTERS FOR SOLAR ENERGY:
WORKING INDEPENDENTLY, GENERATING POWER COLLECTIVELY

There’s a game-changing solar technology out there. It’s a change in how electricity from solar photovoltaics is put to work. It’s a fundamental change in inverters, the devices that convert direct current (DC) electricity generated by solar modules to alternating current (AC) that’s used on the power grid and thus in your home.

The game-changing technology, the micro-inverter, is an inverter that’s attached to each solar module as opposed to a large single inverter for an entire solar electric system. This fundamental change could make it significantly easier to design, build, and monitor solar systems, particularly smaller systems for homes and businesses.

Typically small PV solar systems are made of a group of solar modules (or panels if you like) that are installed like dominoes on the surface of a roof or on a piece of unused real estate. All the modules are mounted on the same plane and are wired together to make an array. All the solar electricity that’s generated from the array is fed to one inverter for AC power. From the inverter electricity goes to things like toaster ovens, lights, ceiling fans or cell phone chargers.

The micro-inverter opens up new doors that will forgo this traditional design and eliminates the need for all the modules to be in one place. Since each module has its own inverter it becomes its own AC-generating, grid-compatible, independent solar power plant. It can work by itself or with others. The more modules working together the more powerful a system becomes.

Without the need to connect modules together and to a single inverter, total system design is easier and simpler. Modules can be mounted in variety of places and not constrained to one location. For instance, for a home solar system some modules might be on multiple faces of the home’s roof. A few modules could go on the garage. Others might become part of a ground mounted array. In any configuration modules will work independently but add power to the system collectively.

Not only can modules be scattered about they can be different sizes and rated outputs - modules can be mismatched. The ability to use different sizes makes it easier to design systems too. Small panels could be mounted in small areas, larger ones in larger areas.

Using micro-inverters, too, allows systems to grow as power needs (or perhaps finances) dictate. As plug-and-play devices new modules with micro-inverter attached can be added as needed: start small and grow over time.

Further, modules that become partially shaded or subject to indirect sunlight, won’t upset the whole system. And, with all modules being independent there is no single point of failure. The system will keep operating if one module goes down.

Enphase Energy, for now, is the primary producer of micro-inverters for solar systems. The company says power from systems using its micro-inverters have demonstrated energy harvest gains of between 5 and 25 percent over those with traditional inverters.

The company also offers monitoring for systems for solar systems with its micro-inverters installed. The devices are Internet enabled and can feed performance information from each solar module to company-created secure websites developed for each system: System owners can then keep tabs on performance module-by-module and make adjustments of necessary.

The cost savings are considerable, too, according to the company. Balance-of-Systems and labor savings can be as much as 15 percent. Enphase products are compatible with most major brands of solar modules and are available from leading solar distributors and installers. The company lists over 100 modules its micro-inverters are compatible with.

Enphase has announced that it has raised $15 million in new funding to expand manufacturing of its groundbreaking products. New investor RockPort Capital Partners led the round, and existing institutional investors Third Point Ventures and Applied Ventures, LLC, the venture capital arm of Applied Materials, Inc., also participated.

If this technology catches on in a big way - which seems possible - solar panel manufacturers might start creating new module designs purpose-built to be used with micro-inverters. It’s a technology to keep an eye on.

Links:

Enphase Energy
http://www.enphaseenergy.com

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