Types of grid-connected inverters

In this blog, we will cover the common types of Grid-Tied or Grid Connected Solar Inverters used in roof-top Solar Power Plants: String Inverters, SolarEdge Optimizer System, and Enphase Micro-inverter System. Solar Power Plants that use only utility grid as a complementary source of power are called grid-tied or grid-connected systems.

Grid-connected PV inverters have traditionally been thought as active power sources with an emphasis on maximizing power extraction from the PV modules. While maximizing power transfer remains a top priority, utility grid stability is now widely acknowledged to benefit from several auxiliary services that grid-connected PV inverters may offer.

In order to provide grid services, inverters need to have sources of power that they can control. This could be either generation, such as a solar panel that is currently producing electricity, or storage, like a battery system that can be used to provide power that was previously stored.

In the grid-connected inverter, the associated well-known variations can be classified in the unknown changing loads, distribution network uncertainties, and variations on the demanded reactive and active powers of the connected grid.

Grid-forming inverters can start up a grid if it goes down—a process known as black start. Traditional “grid-following” inverters require an outside signal from the electrical grid to determine when the switching will occur in order to produce a sine wave that can be injected into the power grid.

There are several types of inverters that might be installed as part of a solar system. In a large-scale utility plant or mid-scale community solar project, every solar panel might be attached to a single central inverter. String inverters connect a set of panels—a string—to one inverter.