Users are also getting more sophisticated and are more frequently requiring the ability to monitor the energy production of the their solar-PV installations. With a string inversion system, most users are only able to measure total system production, as produced by the single inverter. With a microinversion system, each module can be monitored independently, making maintenance and upkeep simpler and more straightforward.
To eliminate any communications wiring needed to accomplish module-level monitoring, most microinversion systems utilize a power line carrier (PLC) signal. That allows a communications signal to be sent out over the electrical conductors used to carry the power that is produced. This information is then aggregated to give system-level performance information, if so desired.
There are several major applications in which microinverters will significantly outperform their string inverted counterparts.
For shade-prone jobsites, microinverter systems give installers much more flexibility in installation location and usable roof area. On the roof of a typical factory, for example, there are rooftop AC units, ventilation systems, and other obstructions like smokestacks, trees, and other tall buildings nearby. Such obstacles present a major problem for string inverted systems. On the other hand, microinverted systems can take full advantage of the space, because the system is not universally affected by efficiency loss, as detailed previously.
For many installations with non-traditional layouts or rooflines, the varying angles present a problem for string inverter systems. For those systems to function at their peak, all the modules need to have relatively the same intensity of sunlight. This forces all modules to be mounted at the same angle of incidence of sunlight, and facing the same direction.
Microinverters will draw maximum power available from the module it is attached to, regardless of its orientation and relative to the installation angle of the other modules in the array. The classic example of this issue is a building with a pitched roof. Regardless of which direction the building faces or the angle of sunlight at a given time, microinverters are able to capture maximum available power from each module.
Microinverter-based installations are also inherently scalable. If a facility owner plans on growing, or wants to increase the capacity of the solar-PV system at a later point, adding modules incrementally is as simple as extending the AC cabling to the next array or set of modules. This is critically important for those enterprises that are in high-growth industries, plan on adding capacity at a later point, or merely want options in spite of not having an immediate need or enough money to implement more power.
Keeping an Eye on Things
Microinverters also capitalize on advanced monitoring capabilities. Arrays or individual modules across multiple installations can be merged into a single monitoring package. This makes monitoring campus or distributed systems much simpler. Each array can be grid tied independently, then monitored as a bundled, single installation. For example, at a college or university, there are dozens of buildings that can each receive their own installation, and can be combined to provide campus-level monitoring.
It’s apparent that recent advances in microinverter technology will only bring good things to the solar-PV universe. Any technology that introduces efficiency, simplicity, performance, and reliability, while driving down cost and complexity, is really going to go places — and not just on Planet Earth.
This article was written by James Washburn, Product Manager, AFCI & GFCI Renewable Energy Products, at Siemens Industry, Inc., Alpharetta, GA. For more information, visit http://info.hotims.com/34454-121.