Solar Inverter Technologies and Grid Connection Features

Connected Network Features

Modern photovoltaic systems are connected to the network with the following essential features:

• Maximum Power Point Tracking: Continuous follow-up of the maximum power point of the PV generator.
• Monitoring and Disconnection: Integrated monitoring system and network disconnection capabilities.
• System Protection: The system is protected against:
  • Short circuits in AC circuits.
  • Mains voltage being out of range.
  • Line frequency being out of range.
  • Overvoltages via varistors or similar components.
• Subsistence Night Mode: Inverter consumption in night mode is less than 0.5% of its rated power.
• Standby Mode: When the power generated is less than required, the system will enter standby.
• Grid Delivery: The system must continuously deliver power to the grid under higher irradiance conditions at 10% EMC conditions.

Central Inverters

In a central inverter configuration, the generator is connected to a single inverter. These are commonly used in many power plants, consisting of many parallel branches of series-connected modules.

This setup allows you to generate high power with good performance and low cost. The disadvantage is that it limits the reliability of the system, as it depends on a single inverter. The insolation should be homogeneous, without any shadows on the branches, and have very low production tolerances. If partial shading occurs, it would be necessary for the generator connections to form chains with few branches or modules in series because they will produce low voltage and high current.

String Inverters

A string inverter (or inverter chain) is formed by several branches of modules connected in series, an inverter, and industry-standard components. These inverters offer higher yields than central plants. Since several branches may have different sunlight conditions, it is not necessary to install blocking diodes, which increases the performance of the installation. Additionally, the installation can be decentralized by placing them next to the modules to reduce wiring.

Multi-string Inverters

The multi-string inverter is an economical solution for installations where there are branches of modules with different operating conditions.

Module-Integrated Inverters

Module-integrated inverters are installed directly in the module and are used where there is little power. The shading of one module does not affect others, and if there is a fault in one inverter, the others continue to work. It adapts to the specific power and voltage characteristics, providing a performance advantage; however, if a major failure occurs in the inverter, it is necessary to change everything.