Photo courtesy of SolarEdge
The module-level power electronics (MLPE) market is one of the fastest growing segments in the PV industry, rapidly moving beyond niche status to become a crucial component of residential and commercial installations. Today, approximately two out of every three residential systems in the United States features an MLPE solution, and analyst reports indicate the global market will reach 5 GW installed by 2017.
The MLPE market includes both micro inverter technologies as well as DC power optimizer technologies. These products enable PV systems to overcome performance challenges stemming from module mismatch, caused by a number of common factors including variances in module tolerance, partial shading, soiling and/or uneven aging. Through maximum power point (MPP) tracking at the module level, MLPE products mitigate mismatch effects and allow each module to operate at their maximum power levels. By eliminating any electrical reason to decrease the size of a PV system, MLPE technologies help designers to install more modules on the rooftop. For installers, this means increased revenues. For end-users, the added system output equates to lower electricity bills.
MLPE systems are also equipped with module-level monitoring to provide operators greater transparency into the performance of a system. Any issues can be pinpointed from a remote location, enabling more efficient maintenance and higher system uptime. Moreover, these systems feature enhanced safety measures that reduce system voltages during instances of extremely high temperatures and/or grid disconnection.
Photo courtesy of SolarEdge
Within the MLPE space, power optimizers are showing the largest percentage increase in customer acceptance. Whereas micro inverter technologies replicate the inverter completely at the module level, power optimizers only deploy a minimal amount of electronics on the rooftop to handle the MPP tracking and DC to DC conversion, leveraging a centrally located inverter at the end of the string. The benefit of this approach is that installers can reduce the hardware on the rooftop improving reliability and slashing costs.
Power optimizers can also be used in a fixed-voltage mode where the inverter determines current draw based on a predefined voltage target. The optimizers will all lock in on the same current value and deliver the remainder of the power as voltage. This advanced mode of operation means that string length is no longer determined by voltage but is now determined by power. The benefit is string lengths that are boosted by 60% in residential systems and by over 4-times in commercial systems. An added benefit is that inverter manufacturers can design inverters to accept voltages at the optimal level for DC to AC conversion reducing the need for DC boosters and other internal components. These reduced parts lead to lower cost products. Fixed voltage mode is the secret sauce for how SolarEdge’s inverters and optimizers function.
Photo courtesy of SolarEdge
Since power optimizers are smaller and more compact, they can also be embedded by module manufacturers during the manufacturing process as a replacement for the traditional junction box. The resulting “smart modules” further reduce parts count and streamline installation at a project site.
The value proposition for power optimizers is compelling, and the market will only grow as providers enhance their performance capabilities and cost structures at the residential, commercial and utility scales. Look for this technology to be a standard component of PV systems of all shapes in sizes in the not-so-distant future.
By Peter Mathews, general manager; and Dru Sutton, technical marketing manager for SolarEdge in North America
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