The photovoltaic industry contributes to global sustainability

In the process of PECVD coating, using EFORT ER15 - 1400 to handle expensive and fragile silicon wafers can significantly reduce fragmentation rates while increasing production capacity © EFORT

According to the United Nations Framework Convention on Climate Change, the photovoltaic industry can generate about 7 trillion watts of electricity per year, which can meet the needs of about 70% of the world's homes, businesses and governments. The rapid development of the photovoltaic industry has promoted the progress of photovoltaic technology and materials, and the environmental and economic benefits it brings have gradually become prominent. Nowadays, the photovoltaic industry has become one of the fastest growing, most promising and most cost-effective sectors in the global energy sector.

Photovoltaic manufacturing process and customer pain points

The thin photovoltaic cells are multi-layer structures, more complex than they seem. To complete the transformation from the most basic silicon material to the final photovoltaic cell module, it roughly needs to go through the main process processes such as industrial silicon, polysilicon, silicon wafers, cells, and modules. They're produced with hundreds of processes. High manufacturing costs once became the main reason for the slow spreading of photovoltaic. The challenges of downstream applications encourage upstream photovoltaic and equipment manufacturers to continuously improve the process, improve production efficiency and yield rates to reduce production costs.

Photovoltaic solutions (cell chip insertion)

PECVD coating is the core process of photovoltaic cell manufacturing. At the manufacturing site of TONGWEI Solar, the silicon wafers are stored in the graphite boat and enter the PECVD device port through the conveyor track. After receiving the sensor signal indicating that the graphite boat is in place, the EFORT ER15-1400 robot uses a special pneumatic clamp to accurately grab out and insert the silicon wafers between the graphite boat and the feeding mechanism.

To achieve better production efficiency, this seemingly simple "loading and unloading" action must be completed in the shortest cycle time and ensure that the expensive silicon wafers that have completed most of the process are intact, which will face many challenges:

• The compact layout of the production line and the limited movement space inside the equipment require more flexible posture;
• Silicon wafer is thin and brittle, easy to fracture, needs more accurate positioning accuracy and stability;
• Extremely clean working environment requires higher protection levels of robots.

The robot directly touches the silicon chip in the process of inserting/taking operation, and the previous achievements will be wasted if there’s a slight mistake, which puts forward higher requirements for the working rhythm, stability and accuracy of the inserting robot. Since Chinese industrial robots started late, domestic enterprises are relatively weak in the accumulation and application experience of robot core technology, therefore, domestic photovoltaic manufacturers once relied on imported products from internationally renowned robot manufacturers in this process. Based on the premise of sufficient market analysis and technical demonstration, ER15-1400 has achieved great performance in many user sites once launched. The users find that this Chinese domestic brand robot can meet the requirements of the working rhythm while running stably, and has better economy.

High protection is the basic requirement for robots in PECVD coating process environment. The product manager of ER15 described: "This product is completely enclosed in its shape of the design, its joint applies a unique double sealing technology, the wrist part reaches IP67 protection level, these measures can effectively avoid the leakage of internal lubricants caused by pollution losses, and also avoid the acidizing fluid during the operation of the robot life." ER15-1400 can be flexibly installed, in addition to the traditional ground installation method, it can also be integrated on the top and both sides of the equipment. It can fully achieve the handling operation of the silicon wafer between two graphite boats and equipment, combined with EFORT TMOVE (time optimal trajectory planning control algorithm) technology, which is a strong guarantee of stable and efficient production capacity.

"Accuracy and stability" are two very important technical requirements of the inserting process. The gap between the silicon wafer and the card slot in the graphite boat is as thin as hair. Considering the possible fixture tolerance, it is necessary to ensure that the trajectory repeatability of the robot is at least within 0.15mm. The highly rigid body design and EFORT's advanced robot motion control algorithms ensure that the robot's joints and arms maintain a good and smooth operating posture during the start, stop and high-speed operation, whether horizontal or vertical. The fixture can be accurately and smoothly inserted into the gap between the silicon wafers without any subtle shake, and the silicon wafers do not scratch when inserting into the narrow card slot of the graphite boat, thus ensuring accurate and stable insert work.

Pass along from customer trust and good reputation, ER15-1400 has gradually grown from a "strong novice" to a star product in the field of photovoltaic insert.