In the solar world, one of the big debates is the whole string inverter vs. micro inverter issue. Solar inverters are the devices that convert DC power being produced by the solar panel into AC power. The debate lies in which type of inverter is better, string or micro, which both have unique functions and compatibility.
The Types of Inverters
Inverters are the element of the solar system that converts DC power into AC power to be sent to the grid. There are two types, as we have mentioned, the single “string” inverter, and the micro inverter. The conventional single “string” inverter is usually located at the ground level of a home, in the garage, or outside with the other electrical panels. This string inverter converts power for all panels in the array. So, if there’s 25 panels, there will still be one inverter.
Micro inverters have been around since 1993, but have only recently gained popularity in their solar applications. Unlike the single “string” inverters, with a micro inverter setup, there is an inverter mounted on the back of every solar panel.
The Benefits of Micro Inverters
Micro inverters, with their setup on each panel individually, have many benefits. The fact that each panel has its own dedicated inverter means that each panel is optimized individually, which ensures maximum production from each panel. This means that one underperforming panel will not bring down the performance of the system as a whole. String inverters optimize for the system as a whole, which can be affected by poorly performing panels.
With Micro inverters, one panel that is malfunctioning will not affect the whole production of the system. This can be useful for any system that may have shading problems. The shaded panel will not affect the performance of the whole system, instead the individual inverter will adjust and treat the panel separately from the rest of the system. With a central inverter, if as little as 9% of the system is shaded, the system will put out 54% less energy. A system generating via micro inverters will not be effected the shaded 9%.
Micro inverters have a much longer lifespan, and therefore warranty, than central inverters. Central inverters, with the entire system running through them, are constantly hit with high power and high heat. This takes a toll, which makes their lifespan and warranty significantly shorter (10-15 years) than that of micro inverters.
Micro inverters allow for your solar system to be added on to or modified easier. If you add a new panel or panels, with micro inverters there is no need to restring your entire system. Also, with a central inverter based system, you may have add another inverter if you add enough panels. This may lead you to buy an inverter that is much bigger than what you need for your system.
Micro inverters, like those provided by Enphase Energy, often come with online performance monitoring systems that allow you to visually monitor the performance of every panel, and your system as a whole. The ongoing monitoring of your system allows you to make tweaks to optimize it, and gives you the capacity to know when certain panels go out or are under performing. The online monitoring provided by micro inverters is the best way for solar customers to ensure they are getting what they were promised as far as electrical production.
In a central inverter solar system setup, the solar panels are strung together in a series before the inverter. This means that there is extremely high DC voltage running through the wiring, which can be extremely dangerous, and life threatening to the homeowner. Micro inverters eliminate this extremely high voltage current, which is safer and more efficient.
Micro inverters produce significantly less heat that central inverters, so no active cooling system is needed, which keeps noise down. This is appealing to most homeowners as nobody wants a noisy solar system.