Single points of failure can plague a home solar system with a central inverter.
Think of a centralized solar system as a string of Christmas lights run in series. If one bulb goes out, the rest go with it. Even shading a portion of one panel in an array can drag the entire array’s energy harvest down. Enphase Energy has laid claim to being the first to produce a microinverter system available for commercial or residential applications. According to a friend of mine in the solar industry, “[Enphase Microinverter systems] are taking the solar world by storm.”
Microinverters reduce the bulk, space and noise of traditional inverters. A microinverter mounts below each PV panel, converts that panel’s DC current to AC and then ties directly into the existing wiring and power panel of the house. This saves the expense of heavy gauge copper wire, as well as the task of running it to your garage (or other centralized location) from the PV array. At a few dollars per foot, that wire amounts to a lot of money in labor and material.
According to the Enphase Energy website, their microinverter can boost performance of PV panels by 5%-25%. The benefit of one inverter per PV panel is the continued production of individual panels, even if one panel of the array is shaded or damaged. In traditional arrays where all the panels are tied together, the least efficient panel drags the rest to its level.
Microinverters reduce the chances of total system failure significantly by isolating the system’s components. Enphase also claims that if a single inverter goes out, repairs can wait until routine maintenance is necessary, which saves the homeowner a lot of pulled hair in the end.
Detractors say that the inverter is the most likely piece of equipment to fail (next to batteries if you are thinking of an off-grid application). They argue that increasing the number of inverters could lead to increased expenses in system maintenance for a homeowner. To help limit premature failure, check if the product you are thinking of purchasing has met Highly Accelerated Life Testing (HALT) and Highly Accelerated Stress Screening (HASS) testing standards. Enphase’s microinverter has passed this testing.
Watch the Enphase presentation about their microinverter system.
Or you can come back here. There will be more said about this exciting new development of the solar world in coming blogs.