Knowledge What Is a Solar Inverter


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A solar inverter converts the variable direct current (DC) output of a photovoltaic (PV) solar panel into alternating current (AC) electricity that can be fed into a commercial electrical grid or used by a local, off-grid electrical network. A solar electric system is typically comprised of solar panels, an inverter, a battery, a charge controller, wiring, and support structure. A charge controller is connected between the solar panels and the battery bank to regulate the power coming from the solar array and going out of the battery. In an off-grid system or grid-connected system with battery backup, the battery bank is charged directly with DC power generated by the solar array and discharges its energy using direct current. In a grid-connected system without battery backup, the solar electric system is connected to a utility grid to complement normal power supply from your utility company. However, most appliances, electronics, and power tools use AC power, and the utility grid that the solar electric system is connected to functions almost exclusively in AC power. Direct current only flows in one direction flows in one direction and cannot take advantage of transformers to step up and step down voltages for delivering electricity across long distances. Therefore, an inverter is required to convert the output from the solar system to AC before it can be supplied to electrical equipment or the electricity grid.

There are three types of inverters; 1) string inverters (also known as central inverters) 2) micro-inverters 3) hybrid string inverters with optimizers. A string inverter is designed to convert direct current to alternating current, from a string of series connected solar photovoltaic panels. These centralized power control units are commonly used in large scale commercial or residential systems generating in excess of 1 kW of power. Micro-inverters are installed on each individual panel and handle much less power. Since each solar panel is operated independently, issues of shading or debris on one panel will not affect the other solar panels in the array. Like micro-inverters, power optimizers are located at each solar panel. However, these devices are used to optimize the DC power of each panel before sending it to a central inverter, thereby increasing the overall efficiency of the system.