As the solar industry heats up and more systems are installed, efficiency is more important than ever. Each solar install is unique and features components to help it reach peak efficiency. Inverters are key components in solar systems, and their performance is essential to a system’s overall performance.
Inverters: What are They?
Solar panels are usually termed the “heart” of the system whereas inverters are generally termed the “brains.” The chief objective of an inverter is to convert direct current (DC) power to alternating current (AC) power. The AC power is in turn used in businesses and homes. In solar, inverters convert DC to AC through power generated by the solar panels as well as stored power in battery banks. Inverters are manufactured with varying attributes such as shape, size, type, features, wattage, and cost; selecting the right one for your system is vital. Bay Area Solar Solutions will assist you in making an informed decision when choosing inverter based on your solar needs.
The two main types of inverters are utility-interactive and stand-alone. Utility-interactive inverters may be grid-direct and battery-based while all stand-alone inverters are battery-based. Ryan Mansfield, President of Renewable Energy Associates, in his book Photovoltaic Design & Installation For DUMMIES, cites that grid-direct inverters are:
“…the most widely installed inverters due to their increased efficiencies and relatively simple installation, and they’re used only in grid-direct (battery-less) PV systems.”
Because Bay Area Solar Solutions primarily focus on grid-direct inverters and their vast popularity among homeowners and businesses, the remaining article will focus on such accordingly. Battery-based inverters will be showcased in a future blog.
Grid-direct inverters feature main characteristics as safety components, maximum power point tracking (MPPT), and a user interface . All grid-direct inverters must be connected to a utility grid and posses a feature known as “anti-islanding.” Anti-islanding occurs when the utility grid goes down (ie, the power goes out), and the inverters immediately turn off to keep power from being produced by the panels. Residential grid-direct inverters also include ground fault protection. MPPT is responsible for delivering maximum power rtecieved by the inverters to the load center. Additionally, features such a user interface allow both manufacturers and purchasers to monitor the efficiency of an inverter.
String Inverters, Microinverters, Central Inverters, and Power Optimizers
The three main types of grid-direct inverters are microinverters, string inverters, and central inverters. Central inverters are primarily used in commercial applications, and will be covered in a featured piece. Relating closely to microinverters are power optimizers, and we shall cover them as well.
Over the course of solar’s history, string inverters have been the standard. String inverters are also called centralized inverters (not to be confused with central inverters). According to EnergySage, your solar panels are arranged into groups connected by “strings,” as each string of panels is connected directly to a single inverter, which transforms the DC electricity produced by the panels into appliance-friendly AC electricity. For example, a row of 5 panels would be connected by a string leading to one inverter, thus the name, “string inverter.”
Microinverters and power optimizers, also called module-level power elcteronics (MLPEs), have recently improved in popularity and efficiency and may eventually surpass string inverters as the DC to AC choice. Microinverters, according to Energy Sage, are installed on each individual panel in a solar energy system. For example, a row of 5 panels would require 5 microinverters (as opposed to the aforementioned 1 string inverter). Microinverted are either located within the panel or mounted close to the panel.
Power optimizers, similar to microinverters, are used with each panel. Power optimizers do not convert DC to AC as microinverters, rather they transfer optimized DC electricity to a string inverter. For example, a system using power optimizers for a row of 5 panels would require 5 power optimizers and one string inverter. Power optimizers are generally combined with the panels for optimum efficiency.
As technology improves, many panel and MLPE manufacturers are combining forces to produce “smart modules.”
So Which is Better?
Each install is unique and requires unique components. String inverters, microinverters, and power optimizers each posses certain characteristics that should be covered when exploring a solar energy system. Manufacturers of such should be considered as well, as not all components are created equal. Features such as warranties, operating temperature range, and efficiency must be taken into consideration. The following chart highlights the main differences between string inverters, microinverters, and power optimizers. Please note that characteristics labeled are general in nature and technology is constantly improving.
The Final Say?
Inverters and power optimizers are constantly making technological strides. The string inverter has had a long, successful run in solar. Microinverters have made solar inroads as of late, and power optimizers are changing the game of solar as well. Bay Area Solar Solutions will work with the customer in determining their inverter/power optimizer needs. Although the customer may be presented with various options, Bay Area Solar Solutions usually works with Enphase microinverters and SolarEdge power optimizers. Enphase and SolarEdge manufacture and offer industry-leading microinverters and power optimizers. Both Enphase’s Envoy system and SolarEdge’s system offer state-of-the-art monitoring services, keeping manufacturers and customers aware of the efficiency of the solar panels/array.
Inverters and power optimizers are invaluable components in a solar energy system. They, along with panels, are constantly improving. And, with Bay Area Solar Solutions, the power to choose solar, inverters, and power optimizers is more bankable than ever.
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