Views: 0 Author: Site Editor Publish Time: 2026-05-19 Origin: Site
As the core component of a solar power generation system, the power generation efficiency and service life of a PV panel depend not only on the material and process of the cell but also on the design of many fine structures on its surface. Grid lines, PAD points, MARK points, and forked notches—these four seemingly insignificant details each play a crucial role, jointly ensuring that PV cells stably and efficiently convert solar energy into electrical energy. Today, we will disassemble these core structures one by one to understand their "hidden functions."
Grid lines are the most intuitive structures on the surface of PV cells. The visible fine lines and wider lines together form the "current transmission system" of the cell, just like the blood vessels of the human body, responsible for the orderly collection, aggregation, and transmission of photogenerated electrical energy.
Grid lines are mainly divided into two types, which have clear division of labor and work together: one is the fine grid lines densely arranged on the surface of the cell, which are thin and evenly distributed. Their core function is to efficiently capture the photogenerated electrons produced by the cell after absorbing sunlight, minimize electron loss, and ensure that every bit of electrical energy is effectively collected; the other is the main grid lines, which are significantly wider than the fine grid lines and are mostly made of highly conductive silver or aluminum. They are equivalent to "main blood vessels," responsible for aggregating the scattered current collected by the fine grid lines and then transmitting it to the external circuit of the cell to complete the initial transmission of electrical energy. Without the efficient work of grid lines, the electrical energy generated by the cell cannot be exported, and the PV panel cannot realize power generation.
If grid lines are the "current transmission network" inside the cell, then PAD points are the "interface" connecting this network to the outside. Officially known as metal contact points, they are specific areas on the cell surface through which the main grid lines pass.
PAD points are specially designed metal electrodes whose core function is to connect the cell and the ribbon—as the "conducting wire" connecting each cell inside the module, the ribbon needs to be closely combined with the main grid lines of the cell through PAD points. On the one hand, PAD points can enhance the conductivity between the cell and the ribbon, reduce contact resistance, and avoid electrical energy loss at the connection part; on the other hand, they can increase the welding strength between the ribbon and the cell, ensure a firm connection between the two, prevent problems such as welding detachment and cold welding during subsequent module processing, transportation, or use, and ensure the stability of the module.
Also known as reference points, MARK points are indispensable "positioning marks" in the cell production process. Although their role seems hidden, they directly determine the accuracy of grid line printing, thereby affecting the power generation efficiency of the cell.
Taking the mainstream TOPCON cell as an example, both its front and back sides need to be printed with grid lines, and the printing of each side is divided into two times: the first time to print the main grid lines, and the second time to print the fine grid lines. Since the main grid lines and fine grid lines need to correspond accurately, any positional deviation will lead to a decrease in current collection efficiency and even cell failure. To solve this problem, 4 MARK points are printed at specific positions on the cell while printing the main grid lines for the first time. When printing the fine grid lines for the second time, the visual recognition system of the screen printing machine will accurately identify the positions of these 4 MARK points, and then make precise adjustments to the printing screen to ensure that the relative positions of the main grid lines and fine grid lines do not deviate, guarantee printing accuracy, and lay the foundation for the efficient power generation of the cell.
Forked notches are a special shape design at the end of the main grid lines of the cell. The seemingly simple "forked" shape is actually to avoid problems such as chipping and microcracks of the cell during the processing process, and is a "protective detail" to ensure the integrity of the cell.
We know that the main grid lines of the cell need to be welded with the ribbon to realize current conduction inside the module. However, if the main grid lines are too close to the edge of the cell, the ribbon will form a certain bulge after welding. During the subsequent module transfer, lamination and other processing processes, the edge of the cell corresponding to the end of the main grid will be subjected to continuous stress due to the bulging ribbon, which will eventually lead to cell chipping and affect the service life of the module.
To solve this pain point, the existing technology usually designs the main grid lines outside the PAD points at the head and tail of the cell into a forked-shaped welding area—this design can avoid the main grid lines directly passing through the welding pads at the head and tail, disperse the stress caused by the ribbon after welding, effectively prevent microcracks and chipping during welding and subsequent processing, not only ensure the integrity of the cell but also improve the reliability of the PV module.
Grid lines, PAD points, MARK points, and forked notches—these four seemingly tiny structures respectively undertake the key roles of current collection, connection and conduction, precision positioning, and protection. They cooperate with each other and are indispensable, jointly forming the foundation for the efficient and stable work of PV cells. The iteration and upgrading of photovoltaic technology are reflected not only in the breakthrough of cell materials but also in the optimization of these detailed designs. Understanding these core structures can not only help us better understand the working principle of PV panels but also make us more clearly realize that every bit of clean electrical energy cannot be separated from the silent support of these "tiny components."
