The strength grade classification of photovoltaic bolts is usually consistent with the strength grade classification standards of general bolts.

The performance levels of bolts used for steel structure connections are divided into more than 10 levels, including 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9, etc. Among them, bolts of grade 8.8 and above are made of low-carbon alloy steel or medium carbon steel and undergo heat treatment (quenching, tempering), commonly known as high-strength bolts, while others are commonly referred to as ordinary bolts. The bolt performance grade number consists of two parts of numbers, which respectively represent the nominal tensile strength value and yield strength ratio of the bolt material.

For example, a bolt with a performance level of 4.6 has the following meaning:

The nominal tensile strength of the bolt material reaches 400MPa level;

The yield strength ratio of bolt material is 0.6;

The nominal yield strength of the bolt material is 400 × 0.6=240MPa grade.

For example, high-strength bolts with a performance level of 10.9 are made of materials that have undergone heat treatment

The nominal tensile strength of the bolt material reaches 1000MPa level;

The yield strength ratio of bolt material is 0.9;

The nominal yield strength of the bolt material is 1000 × 0.9=900MPa grade.

In photovoltaic systems, commonly used bolt strength grades include 4.8, 8.8, 10.9, etc. High strength bolts have higher strength and reliability compared to ordinary bolts, and can meet the long-term stable operation requirements of photovoltaic systems in outdoor environments. However, the specific strength grade of bolts to be used needs to be comprehensively considered based on factors such as the design requirements of the photovoltaic system, installation environment, and cost.