String Inverters vs. Microinverters: What’s the Difference?
Micro and string inverters are easily confused. Having a sound knowledge of the difference between the two helps individuals determine which is a better fit for their situation.
How Inverters Work
Before we can dive into the difference between inverter types, a basic understanding of what an inverter does is needed. An inverter is a device used to convert the current that is gathered by solar panels (direct current or DC) into a usable current known as alternating current (AC). Without an inverter, the electric current produced by a solar array would be useless to a homeowner.
The String Inverter and its Evolution
String inverters were the first inverter type to be produced. Although technology has evolved string inverters are still widely used by many installers.
How a String Inverter Works
A string inverter has a line of solar panels that are all connected on the same string. The string of solar panels needs to be the same length, angle and type of solar panel for the inverter to perform accurately.
String inverters have issues performing if any of the solar panels are shaded. This is because the shading of one solar panel affects the production of the entire system.
The inverter also can’t tell specifics about issues with the system. If a string inverter array has an issue a professional would have to test all the solar panels to find the problem area and then find the cause of the issue.
String Inverters With Optimizers
To help with string inverter performance issues, companies like Solaredge have created a string inverter that uses power optimizers on the back of each solar panel. An optimizer helps stabilize energy production so that shaded solar panels aren’t as big of an issue.
Energy production is stabilized because the optimizer allows each solar panel to produce optimally and then converts it to the right voltage and current for the array. When the optimizer does this it increases the inverter’s maximum power point tracking(MPPT).
Optimizers also allow all the modules within an array to be monitored. Although better than a traditional string inverter there is still a single point of failure which means the whole system will shut down if there is a problem.
Microinverter Solution to String Issues
Microinverters were created as a solution to the shading problems that string inverters were having. They inspired the invention of the power optimizer.
The Differences in a Microinverter
A Microinverter has a mini inverter connected to the back of each solar panel so that it can convert maximum power from DC to AC. This allows the array to get the maximum power possible no matter if one solar panel is being shaded or not.
There have been some questions raised about microinverters heating the solar panels, but Greentech media has stated that if the microinverter is installed properly, there will be a large enough gap between the solar panel and the inverter that the heat from the inverter will have a minimal effect on the performance of the solar panels.
Microinverters solve the shading problems that occur in a traditional string system, but they also have problems. The main issue with these systems is that they cost more, but they also involve more wiring. Another issue is that because there isn’t one central inverter, the system can’t be easily managed from the ground.
Go Solar Group’s Solution: String Inverter With an Optimizer
Go Solar Group uses SolarEdge’s optimized string inverters. The SolarEdge inverter allows the array to have maximum power when there is shading on a couple of solar panels with less hassle and cost.
We use the SolarEdge because it allows homeowners to add a solar backup option to their system either now or down the road. It also has an automatic shut-off switch that is compliant with the 2019 rapid shutdown requirements.