What is a String Inverter?

The inverter is a critical component of every solar energy system. Without a properly functioning inverter, the energy created by your solar panels would have nowhere to go. It’s a crucial technical element of the system which keeps your solar power generation and use regulated and running smoothly. For a quick review of inverters, the different types available, and the tasks they perform, see What are Solar Inverters?

Here, we will focus specifically on what a string inverter is. String inverters (sometimes also referred to as central inverters) are often described as the most simple and affordable option of the inverters available, and they get their name from the way they string your solar panels together into one cohesive system.

How String Inverters Work

String inverters work by connecting several solar panels in a series to form a string. The DC (direct current) electricity from each panel flows through a wiring harness to the inverter, where it is converted to AC (alternating current) electricity. As AC power, this electricity is fed into your electrical panel, where it can power your home or be sent to the utility grid, depending on your setup.

The principal downside of string inverters is the whole string or series of panels can be negatively impacted if one of the panels is not functioning properly or falls under shade. This may reduce the energy output of your panels or take down the entire system.

String Inverter Types

There are different types of string inverters used in solar installations, including standard string inverters, optimized string inverters, and hybrid string inverters. Each type has its own advantages and disadvantages, depending on the size, design, and location of your solar system. Some factors to consider are efficiency, reliability, cost, warranty, and compatibility with other solar components.

Standard string inverters are the simplest and most economical type of solar inverter. They are suitable for solar systems with uniform shading and orientation, as they operate at the average output of all the panels in the string. They do not allow individual monitoring of each panel, so it can be difficult to detect and troubleshoot any issues that may arise with the system.

Optimized string inverters are similar to standard string inverters, except they have a power optimizer for each panel. A power optimizer is a device which adjusts the voltage and current of each panel to maximize its output. Optimized string inverters are more expensive than standard string inverters, but they offer better performance and efficiency. They also allow for individual monitoring of each panel, which can help identify and resolve any problems arising with the system.

Hybrid string inverters are a combination of a standard string inverter and microinverters. Microinverters are devices which convert the DC power from each panel into AC power at the level of each solar module. Hybrid string inverters include a microinverter for each panel as well as a central inverter which synchronizes and manages the AC power from all the microinverters. Hybrid string inverters are the most expensive type of solar inverters, but they offer the highest performance and flexibility across all types of roof conditions. They also allow individual monitoring of each panel, as well as battery integration and grid support features.

Installing String Inverters

String inverter installation involves connecting several solar panels in a series to form a string, and then connecting the string of panels to the central inverter for electrical conversion. If a solar panel gets damaged or needs a replacement, installing a new panel within a string inverter environment can be done more easily and with less cost compared to other types of inverter installations. You should reach out to your original solar installer for all questions about adding new panels.

String Inverter Durability

The durability of string inverters is another factor to consider as the average lifespan of string inverters is less than 15 years. This is significantly shorter than the average lifespan of solar panels (30+ years), which means you may have to replace your string inverter at least once throughout your system’s lifetime, adding to the overall cost and maintenance of your system. 

The durability of string inverters also depends on the quality, warranty, and efficiency of the inverter model and brand. Some string inverters may have longer warranties, ranging from 10 to 20 years, which can provide more protection and peace of mind. There are also string inverters with higher efficiencies, which reduce the energy loss and heat generation during the conversion process and extend the lifespan of the inverter.

Advantages and Disadvantages of String Inverters

In summary, string inverters have advantages and disadvantages which need to be evaluated based on a number of factors including your location, physical site requirements, budgets, etc. Our experts at Blue Raven Solar will help you sort through all of these variables to determine the proper equipment for your home, budget, and energy goals for a streamlined solar installation experience and to help you know you have the right system for your needs.

Advantages:

• String inverters are easy to install and maintain, as they have fewer components and wires than other types of inverters.
• They generally cost less than other inverters or power optimizers.
• They make it easy to add panels to a system or replace a malfunctioning panel.
• They typically include comprehensive warranties for the expected life of the inverter.

Disadvantages:

• String inverters can reduce the overall performance of the solar system if one or more panels become shaded or damaged because they lower the output of the entire string to match the weakest panel.
• They do not allow individual monitoring of each panel, so it can be difficult to detect and troubleshoot issues or problems with the full system.
• They may require additional equipment to be installed, such as a rapid shutdown device, to comply with safety codes and regulations.
• Though they have comprehensive warranties, string inverters typically do not last the entire lifetime of your system.

For more information on the advantages and disadvantages of all the different types of inverters be sure to check out the previously mentioned What are Solar Inverters? article. 

Though Blue Raven Solar does not typically install string inverters—we’ve found Enphase microinverters to be the best option in the majority of cases—we are here to educate and provide helpful resources on all components of a residential solar panel system. 

Our expert teams will guide you in the selection process of all your solar equipment, including inverters, and will ensure the most advantageous and appropriate solar configuration for your power and geolocation needs. Reach out to one of our solar experts to get a free savings estimate today!