What are micro inverters and how do they work?
Micro inverters (also spelled as one word, microinverters) convert direct current (DC) from a PV module to alternating current (AC). What differentiates microinverters from traditional inverters is that they offer this conversion for individual PV modules (either 1 or 2) rather than a whole array of modules (typically 7-13). So, if you are planning a system size of less than 3kW, this type of inverter would be right for you.
Solar micro inverters offer the ability to increase the overall efficiency of a PV system that is subject to partial shading. When a PV module is shaded, it will produce less power, and therefore produce less current. When this happens on a traditional string array with multiple modules in series, each module will lower their current output to match the current of the shaded panel. This will, in effect, seem like all the modules in the array are shaded and your system will produce much less power than what the one shaded panel is losing. With a microinverter system, this isn’t an issue since each module is producing power in parallel to one another. So if one module is shaded, it won’t affect the output of another module on the string. This means that your system will produce more overall power if you have a partial shading issue.
Micro inverters are also easier to design and install. Homeowners who are looking to install a PV system but are intimidated by high voltage DC systems can rest easy. If they are capable of installing an AC outlet in their home can easily learn to install a PV system with micro inverters. The reason is that all of the wiring is generally 20A or 30A AC wiring, which is the same as most household circuits. More AC wiring also allows the system to follow newer NEC codes and therefore be a safer overall installation.
We would generally suggest microinverters for a solar installation that is smaller than 14kW, which would cover most residential systems. Generally if a system is larger than that, one may want to consider other cost factors such as mounting system configurations, three phase grids, and competitive string inverter systems.
See the different types of solar micro inverters offered at Renvu:
APSystems Micro Inverters