As a Product Manager here at altE, I recently had the opportunity to attend an Enphase training and chat with their reps regarding their plans for new products in 2012. Enphase Energy has become the first company to successfully manufacture, market, and sell the “micro-inverter”. For the past three years they have modified and changed their hardware numerous times in an effort to streamline the micro-inverter system.
If you’re not familiar with the Enphase micro-inverter and why it is special, here is a quick run down. In the past, grid-tied solar electric systems (also known as photovoltaic or PV systems) have had the same general layout. The system has a single DC to AC inverter, which converts the DC voltage being generated by the solar modules to AC voltage that is fed back into the power grid. The micro-inverter changes this layout, by attaching a small inverter near each solar module (generally they are attached to the module racking system). The micro-inverter’s attachment cables connect to the solar module and it converts the DC voltage being generated to AC voltage right there at the module. The AC output can be combined with the outputs of other modules into a single circuit and fed back to the power grid.
There are benefits to having a system layout with many small inverters instead of a single large inverter. First, it gives the system reliability by not having a single point of failure. If a module or an inverter is having an issue, it only affects the output of one module, as opposed to the entire system. In a single large inverter system, if one solar module is being shaded, it negatively affects the output of other modules in the system. The micro-inverter decentralizes this so that if one module is being shaded, the output of that particular module is the only one that will drop. A multiple inverter system also gives the flexibility to start small, maybe with just a few inverters, and then grow piece by piece.
Enphase has changed their systems a little bit each year, and 2012 will be no exception. They are calling their next line of technology the AC Module, “ACM” for short. The ACM micro-inverter will actually be attached directly to the junction box on the back of the solar module. The Enphase reps also referred to this setup as a “back sheet mounted inverter”. Now this won’t work with just any old solar panel! Enphase has been working with manufacturers like Sharp, Yingli and Trina Solar to create a specialized junction box on the back of the solar module that will plug right into the ACM directly. There has been discussion on whether or not the ACM will be sold already pre-installed with the solar module, or if the two components will be sold separately. Based on export charges for AC vs. DC products out of China, they seemed to be leaning towards the specialized solar module and the ACM micro-inverter being sold separately.
Enphase is still in the process of ironing out some minor design details. They’ve had to tweak their passive cooling system to keep things from getting too hot underneath the module and are still solidifying design plans with module manufacturers for the specialized junction boxes. It will be exciting to see this new step in micro-inverter technology. A back sheet mounted inverter could be the next sweet thing to streamline solar installations. Enphase says they are on track to have these out the first part of next year, so hopefully we’ll see the ACM sooner rather than later in 2012.