The PV inverter was originally named for its main function of AC-DC conversion, but as demands are increasing on PV systems, the inverter’s role has since expanded. This role expansion can be compared to how cell phones were once mainly used to make calls, but today smart phones have numerous other capabilities. Functioning as the brain of PV systems, advanced inverter solutions are now responsible for a plethora of roles including, communications, monitoring, smart energy management, grid interaction, safety and more. As such, PV systems are able to become advanced distributed energy power stations and open up a new world for smarter consumption.
One of the first steps for expanding the role of inverters in PV system is to increase their communications functionality as it allows for additional types of capabilities to be implemented. However, for its own purpose communication with the inverter is becoming a growing need for installers and system owners alike –for monitoring, remote access, and/or upgrades. For a comprehensive communication system, the first link in the chain should be from the module to the inverter. For instance, with SolarEdge power optimizers, the communications from module to inverter is conducted via Power Line Communication (PLC), so no special wiring is required. However, the link from the inverter to the cloud can be more complicated. There are multiple new strategies that can be embedded into inverters, such as Wifi, ZigBee, and cellular to allow for easy and simple communication.
In terms of monitoring capabilities, the inverter is becoming a key part in providing insight into system production. However, traditional string inverters provide limited access to information. String or system level monitoring can indicate underperformance of the array, but little else. In order to inspect system issues, skilled technicians have to perform inefficient onsite troubleshooting on inverters operating under load and on DC lines up to 1500V. They connect expensive equipment to the arrays in an effort to search through the haystack of complex IV trace curves to detect the needles. However, as the role of inverters expand to include managing and monitoring energy at the module level, then inverters can track module-, string-, and system-level data to enable greater resolution into system performance. With remote troubleshooting capabilities, these inverters are now responsible for O&M activities and transforming PV asset management from being a manual, resource-intensive process to more of an automated, at-a-glance, remote service.
As part of their expansion, inverters also play a critical role in increasing self-consumption, as they now offer smart energy management solutions. For export limitation and metering, many inverters now offer an embedded meter and an export limitation option integrated into the inverter firmware. By dynamically adjusting PV power production, these new functionalities of inverters allow system owners to use more energy for self-consumption when the loads are high, while maintaining the export limit when the loads are low. For PV plus battery systems, the inverter also plays a key role. While of course the quality of the actual battery is important, it is the inverter that is responsible for its functionality. For instance, a top-of-the-line guitar is only decoration without a talented musician to play it. Like the musician determines how the guitar is played, the inverter controls when the PV is utilized, stored in a battery or transferred to the grid. It is the inverter that determines when the battery is charged, idle, or discharged to generate the maximum economic return.
Another direction in which the inverter role is expanding is its ability to support load management. Helping to offset the impact of rate design and increase self-consumption, inverters can help to shift consumption patterns to match peak PV production to loads, such as water heaters, air conditioners, and pool pumps. As inverters already manage PV generation and consumption, it is a natural progression to integrate PV with smart homes and for the inverter to be the control unit. With this new functionality, inverters offer load management control that can be coordinated with a homeowner’s PV production.
Due to increased safety awareness in combination with evolving PV markets and proliferation of solar energy, safety is another area in which inverters have a growing role. With regulations being called for by fire authorities, insurance companies, and utility companies, experts in the fields of electrical safety, PV, fire safety, and insurance are working together to develop new PV safety codes. The responsibility of meeting the new safety codes is being placed on the inverter. As such, inverters are now being designed to meet these new codes. Inverter systems that include MLPE solutions are particularly cost-effective and successful at meeting these requirements as they can reduce DC voltage at the module level.
While this trend towards expanding the role of the PV inverter is putting a greater responsibility on the inverter and manufacturer, it is a necessary step in the advancement and proliferation of the solar energy systems. Just as in the past few years, inverters had to advance to address the larger role that they play in determining PV systems’ bottom line and lifetime value, this new trend will also be addressed by the market through product innovation.
Lior Handelsman founded SolarEdge in 2006 and currently serves as vice president, marketing and product strategy where he is responsible for SolarEdge’s marketing activities, product management and business development.