There are two types of inverters used in photovoltaic systems: micro inverters and string inverters. Both have MC4 connectors to improve compatibility.
String inverters and micro inverters
Series inverter or centralized inverter is the most common choice in photovoltaic devices, suitable for series or series parallel solar panels. A centralized inverter converts DC power to the entire series, which is why it is recommended for use in photovoltaic systems that are not partially shaded.
Micro inverters can be used for photovoltaic devices that will or will not be partially shielded, and even for devices that will be modularized and expanded in the future. Micro inverters convert direct current from a single module to alternating current, with a 120V AC output, which is why solar panel arrays with micro inverters are specifically connected in parallel.
Solar panel array configuration
Planning the configuration of solar panel arrays will help you ensure the correct voltage/current output of your photovoltaic system. In this section, we will explain what these projects are and their importance.
Maximum DC input voltage
For safety reasons, NEC regulations, and compliance with the technical specifications of string inverters, the maximum DC voltage must be limited. According to NEC regulations, the limit for residential photovoltaic systems is 600V, but this may vary depending on the centralized inverter.
Minimum DC input voltage
Starting a string inverter requires a minimum DC input voltage, which is why it is an important planning configuration for photovoltaic systems. This number varies greatly depending on the selected model and brand.
Maximum DC input current
The maximum DC input current is limited by the inverter technical specifications. This value is designed after the current voltage curve (IV curve) of the solar cell. This is an important factor to consider when connecting solar panels, as the system’s DC output should not exceed the maximum input current of the inverter.
Number of MPPT trackers
The MPPT tracker optimizes the power output of photovoltaic systems considering the IV curve. A centralized inverter with multiple MPPT trackers can optimize the power output of solar panel strings with different specifications, allowing you to connect more complex solar panel arrays to the inverter. If your inverter has two or more MPPT inputs, make sure to use them correctly, especially in scenes with multiple directions or shadow effects.
