Solar power production is affected by module mis-match, obstruction shading, inter-row shading, and dust or debris. In addition, non-uniform changes in temperature, irradiance, and shading create complex current-voltage curves, further affecting energy harvest. This is because in traditional systems the performance of the entire system is dictated by the performance of the weakest module.
Microinverters solve these challenges by performing Maximum Power Point Tracking (MPPT) at each solar module. MPPT is an algorithm used to calculate and respond to temperature and light changes detected on a solar power system, and to determine how much power to draw from the module. In contrast, centralized inverter’s MPPT algorithm sees the entire solar power system as a single module, and responds to the lowest production numbers it detects.
Microinverter manufacturer Enphase’s MPPT algorithm works at each solar module in an installation and achieves greater than 99.6% accuracy, which enables it to maximize energy harvest at all times, even during variable light conditions. Enphase says tests show systems using their microinverters increase energy harvest by as much as 25% over systems using traditional inverters.
Microinverters shift DC to AC conversion from a large, centralized inverter to a compact unit attached directly to each solar module in the power system. Distributing the conversion process to each module makes the entire solar power system productive, reliable, and safe.
Traditional centralized inverters’ implementations create a single point of failure for solar power systems. If the inverter fails, the entire system is disabled. Enphase Microinverters convert power independently at each solar module. If one microinverter fails, the rest continue to operate as usual. Also, if a microinverter is damaged or fails, it can be replaced during routine maintenance or when convenient, further reducing maintenance costs.
Enphase says with its microinverters, installers are no longer limited by string design, marginal designs, co-planarity, and matched modules. The space, heat, and noise associated with a large inverter are eliminated. Microinverters improve mechanical integration, reduce wiring time, and remove the need for DC switching points.
Another benefit of the distributed microinverter design is the potential for installations to be expanded over time. An initial set of solar modules can be installed and additional modules added as needs and budgets grow without requiring the replacement of a large centralized inverter.
The Enphase microinverter is CSA Listed per UL1741 and can withstand surges of up to 6kV. Independent testing by Relex – a leading third party reliability expert – has shown an estimated Mean Time Between Failure (MTBF) of 331 years for Enphase microinverters. The company offers its microinverter in M190, M210, and D380 models.
Enphase Energy www.enphaseenergy.com
Kathleen Zipp says
nice point Chris, thanks! Well stated.
Christof says
Don’t forget snow. We’ve discovered snow is a much bigger shading issue than we thought in our first year with a central-inverter based system in the Denver, Colo. area. With microinverters, sweeping snow off pays off much more quickly and doesn’t require a perfect sweep job like a central inverter system does. It also means even if you do not sweep snow off, you’ll invariably get more production because snow melts at variable rates on your rooftop panels and with microinverters a single panel that has that last bit of snow on it won’t bring down a whole string or system. http://solarchargeddriving.com/editors-blog/on-going-solar/607-snow-on-solar-panels-six-design-considerations.html