The welding strip is an important raw material in the welding process of photovoltaic modules. The quality of the welding strip will directly affect the collection efficiency of the current of photovoltaic modules and greatly affect the power of photovoltaic modules.

The welding strip must be firmly welded in the process of connecting the battery sheets in series to avoid false welding. When selecting the welding strip, the manufacturer must decide which state to use according to the characteristics of the selected battery chip. The generally selected standard is to determine the thickness of the welding strip according to the thickness of the battery sheet and the short-circuit current. The width of the welding strip shall be consistent with the width of the main line of the battery. The hardness of the welding strip generally depends on the thickness of the battery sheet and the welding tools. Manual welding requires that the softer the welding strip is, the better. The soft welding strip will be in good contact with the battery after the soldering iron passes by. The stress generated during welding is very small, which can reduce the fragmentation rate. However, the tensile resistance of too soft welding strip will be reduced and it is easy to break. For the automatic welding process, the welding strip can be slightly hard, which is conducive to the straightening and pressure welding of the welding machine. The too soft welding strip is easy to deform when welded by the machine, thus reducing the product yield.

The electric soldering iron used for welding the strip has different choices according to different components. Generally speaking, small photovoltaic modules such as welding lamps have low requirements for soldering iron, small components have small area, and do not have high requirements for soldering iron heat. Generally, 35w electric soldering iron can meet the requirements for welding lead containing strips. However, when welding lead-free strips, it is recommended that manufacturers use 50w electric soldering iron as much as possible, and use lead-free long-life soldering iron head, because lead-free soldering tin oxidizes quickly, The damage to the soldering head is considerable.

It is relatively easy to weld lead-free strips. Generally, as long as the proper flux is selected, the soldering iron temperature compensation is sufficient. However, lead-free strips are troublesome to weld, and many manufacturers feel headache. First of all, a suitable electric soldering iron should be selected for lead-free soldering. For manufacturers, it is a good choice to choose a lead-free soldering station with adjustable power. Generally, the lead-free soldering station is DC powered, with adjustable voltage. The advantage of DC electric soldering iron is fast temperature compensation, which is incomparable to AC temperature regulating electric soldering iron. The soldering iron of 70-100w shall be selected according to the thickness and area of the battery sheet for lead-free soldering strip. The soldering iron of less than 70w will generally have problems during lead-free soldering. In addition, many kinds of lead-free temperature regulating AC soldering irons (controlled by a thermal magnet) on the market are not suitable for welding large areas of battery chips, because the silicon thermal conductivity of the battery chips is very good, the heat of the soldering iron tip will be transferred to the silicon chip quickly, which will instantly reduce the temperature of the soldering iron tip to below 300 degrees. The temperature compensation of the soldering iron is not enough to ensure the temperature of the soldering iron rises to 400 degrees, which cannot ensure the fastness of lead-free welding, The resulting phenomenon is the crackling sound of the battery sheet during welding, which seriously causes the battery sheet to crack immediately, which is caused by the shrinkage stress caused by low soldering temperature. The lead-free soldering tip oxidizes very quickly. It is better to keep the tip clean. It is better to bury the tip into the solder when it is heated. Before use, remove the excess solder from the tip. The contact end of the soldering iron head and the welding strip shall be repaired to be consistent with the width of the welding strip as far as possible, and the contact surface shall be flat. Lead free and residue free flux shall be used for welding.

In the process of welding lead-free solder strip, the manufacturer should pay attention to adjusting the welding habits of workers. The fluidity of lead-free solder is not good, and the welding speed is much slower. When welding, you must wait until the solder is completely melted before walking the soldering iron. The soldering iron should walk slowly. If it is found that the solder is solidified in the process of walking the soldering iron, it indicates that the temperature of the soldering iron head is low. The temperature of the soldering iron head should be adjusted until the soldering iron moves smoothly and the solder flows smoothly.