Micro and string inverters are easily confused. Having a sound knowledge of the difference between the two will help you determine which is a better fit for your situation.
How Inverters Work
Before we can dive into the difference between inverter types, you need a basic understanding of what an inverter does. An inverter is a device used to convert the current that is gathered by your panels (direct current or DC) into a usable current known as alternating current (AC). Without an inverter, you would have no way to use the higher voltage that is produced from a solar array.
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 panels that are all connected on the same string. You need the string of panels to be the same length, angle and type of panel for the inverter to perform accurately.
String inverters have issues performing if any of the panels are shaded. This is because shading of one panel affects the production of the entire system.
The inverter also couldn’t tell you any specifics about issues with the system. If you had an issue a professional would have to test all the panels to find the problem area and then find the cause of the issue.
String Inverters with Optimizers
To try and help with their performance issues, companies like Solaredge have created a string inverter that uses power optimizers on the back of each panel. An optimizer helps stabilize energy production so that shaded 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 you to monitor all the modules within an array. Although better than a traditional sting inverter you still have a single point of failure which means your 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 panel so that it can convert maximum power from DC to AC. This allows you to get the maximum power possible no matter if one panel is being shaded or not.
There have been some questions raised about microinverters heating up the panels, but Greentech media has stated that if the microinverter is installed properly, there will be a large enough gap between the panel and the inverter that the heat from the inverter will have a minimal effect on the performance of your panels.
Microinverters solve the shading problems that occur in a traditional string system, but they have their own problems. The main issue with these systems is that they cost more, but they also involve more wiring. And because there isn’t one central inverter you can’t easily manage your system from the ground.
Go Solar Group’s Solution: String Inverter with an Optimizer
Go Solar Group uses the SMA sunny boy on most of their installs, but if the situation calls for it, they use Solar Edge’s optimizer sting inverters. These are both string inverters, but the Solar Edge inverter will allow you to have maximum power when there is shading on a couple of panels with less hassle and cost.
We decided to stick with SMA’s Sunny Boy because they are the best of the best in string inverters. They combine German engineering with American manufacturing. Both of our inverter options allow you to add solar backup to your system either now or down the road.