String Inverters vs. Microinverters: What’s the Difference?

Micro and string inverters are easily confused. Learning the key differences between these two common inverter types can help homeowners determine which inverter and therefore solar company is best for them.

How Inverters Work

Before we dive into the difference between inverter types, let’s cover their basic functions. All inverters convert direct electrical current generated by their solar modules (DC) into a usable electrical current for the home, which is also known as an alternating current (AC).

String Inverters

String inverters are the original inverter type. Although technology has evolved, many installers still use string inverters.

How a String Inverter Works

A string inverter connects a line of solar panels on the same string. This string of solar panels needs the same length, angle, and solar panel type in order for the inverter to function.

One downfall of a string inverter is that modules working via these inverters will have issues performing if any of the solar panels are obstructed by shade. Since panels fed by these inverters feed electrical currents through several strings, the shading of one solar panel can affect the production of the entire solar array.

String inverters are also incapable of detecting specific issues with the whole solar array because they can’t determine the production of each solar panel. Therefore, when string inverter arrays have problems, a professional usually has to test all the solar panels to detect the problem and fix the issue.

String Inverters with Optimizers

To reduce string inverter performance issues, companies like Solaredge use string inverters that use power optimizers on the back of each solar panel. An optimizer helps stabilize energy production, so a few shaded solar panels won’t stop the entire array from functioning. They may also have varying lengths of strings in multiple directions, which makes adding solar to smaller spaces possible, something of great use with complicated, haphazard roofs.

Energy production is stabilized when the optimizer allows each solar panel to produce optimally and convert the current into usable voltage for the array. In this process, the optimizer increases the inverter’s maximum power point tracking (MPPT). Optimizers also make it possible to monitor all the solar modules in a given array.

Microinverters

Microinverters emerged to solve the shading problems inherent to string inverters, also inspiring the invention of the power optimizer.

The Differences in a Microinverter

Microinverters consist of mini inverters connected to the back of each solar panel so they can convert maximum power from the DC to AC transduction process. Unlike their string inverter counterparts, microinverters allow the array to reach its maximum possible production, regardless of whether one solar panel is shaded.

Some homeowners may have questions about microinverters’ role in heating solar panels. However, Greentech Media states that if installed correctly, there will be a large enough gap between the panel and the inverter to mitigate any performance issues.

Microinverter Challenges

While microinverters solve the shading dilemmas occurring in a traditional string inverter system, they are not without downsides, which include cost, the amount of wiring requires, and the fact they must be installed on top of a home’s roof.

Go Solar Group’s Solution: A String Inverter with an Optimizer

Go Solar Group uses SolarEdge optimized string inverters. The SolarEdge inverter allows the array to have maximum power even when a couple of solar panels don’t produce correctly with less hassle and cost.

We use the SolarEdge inverter for all residential installs since it allows homeowners to add a solar backup option to their system at any time. It also has an automatic shut-off switch, which is compliant with the 2019 rapid shutdown requirements.

Video: Comparisons of all Three Inverter Types