Solar Inverters Are Getting Brainier Keeping In Pace With Smart Grid

If solar inverters are considered the “brains” of a solar system, SMA is the Einstein of the group. Inverters in general are key in a solar systems operation, not just because an inverter converts DC electricity (Direct Current (Flows in one Direction)) to AC electricity (Alternating Current (Flows back and forth in both directions)), but because they do much more than that. Technology is demanding that solar inverters become “smarter” when they interact with the household and the grid.

SMA is the largest solar inverter companies in the world and one of the oldest. This Germany based solar inverter manufacturer makes inverters for nearly every application. That’s news enough, but the company is a leader in the industry because they are always challenging new innovation with better products.

Inverters are going to be depended upon to provide more than just DC to AC conversion in solar systems. As photovoltaic solar power becomes more prevalent and as solar penetration on the grid grows, inverters are going to increasingly be depended on to provide ancillary services in addition to just straight DC-to-AC conversion. These new services will look different for small residential and commercial applications versus utility-scale, but in any case, the role of the inverter is likely to grow.

solar inverters

SMA is Usually our First Inverter of Choice

Advanced Energy, Enphase, Petra Solar, Satcon, SMA, and SolarBridge are just a few of the inverter firms exploring these new inverter functions. Greg Madianos, the Marketing Director at Solar Bridge, is on an Electric Power Research Institute (EPRI) committee for grid integration standards for inverters and says that his firm “is building a lot of this capability” into their micro inverter. It’s in “recognition of the fact that every inverter from solar panel level to megawatt-scale is increasingly part of the grid and has a role to play in the stability of the grid.” SolarBridge’s microinverter “can provide VAR support from 0.9 leading to 0.9 lagging and is “future-proof” by virtue of firmware upgrades.

EPRI is performing its research to analyze the impact of voltage control strategies on distribution systems. The focus of the analysis is on the use of smart inverters to provide optimized volt/var support in conjunction with grid-tied solar PV.

EPRI’s inverter integration standards committee, helmed by Brian Seal in Tennessee, is tasked with formulating protocols and standards for the emerging role of solar PV inverters. These functions are still being explored but include Low Voltage Ride Through (LVRT), automatic provisioning, curtailment, and supporting the grid in situations of low and high voltage. These features are not all here today, but that list is a useful start.

These qualities will be tested in areas or circuits where there is a particularly high solar PV penetration say, an island like Hawaii or a military facility like Nellis AFB in California. Advanced Energy is working to address these challenges with partners Portland General Electric (PGE), Schweitzer Engineering Laboratories (SEL), and Northern Plains Power Technologies (NPPT) under the Solar Energy Grid Integration System (SEGIS) program

Advanced Energy claims, “The SEGIS program advancements will help lay the foundation for an “intelligent” or smart inverter capable of integrating large-scale solar photovoltaic power generation into the smart grid with greater stability and protection, with fulfillment at a far more competitive levelized cost of solar energy. By providing the monitoring, control, and other capabilities utilities need to successfully integrate high penetrations of distributed solar photovoltaic power, the industry will be in a better position to satisfy even the most aggressive Renewable Portfolio Standards.” AE has a white paper on the topic available for download at their site.

Germany’s SMA, the solar inverter market leader, is part of the E-Energy program, a project initiated by Germany’s Federal Ministry of Economics and Technology. The project looks to explore the use of IT and communications in the smart grid and in microgrids.

A central aspect of the program is the “self-consumption of solar power.” SMA’s Sunny Home Manager looks to offer a way of controlling home appliances in conjunction with a PV system’s inverter. Germany’s Renewable Energy Act envisions self-consumption of solar power as a benefit in its effect of reducing strain on the national grid.

Satcon provides low-voltage ride-through in their utility-scale inverters, as does SMA. Steve Rhoades, CEO of Satcon, has spoken of inverters integrated with a small amount of lead-acid battery storage capacity. It would seem a natural for inverters to support some level of storage capability.

SMA’s Jim Morgenson said, “For utilities to fully embrace PV, solar has to be an asset, not a liability.” (Story Source Green Tech Media)