As the worldwide leader in the development and manufacturing of industrial laser systems and with more than 35 years of experience in laser material processing, Rofin has developed solutions for all industrial laser applications within the solar cell manufacturing industry.
Rofin chose the recent EUPVSEC 2011 as the venue to debut new product innovations and high end industrial laser solutions for the solar manufacturing and solar research and development sectors.
Rofin offers a wide range of laser sources for solar thin film edge deletion applications. The 1000 Watt DQ010 laser offers the highest available power in the laser market for edge deletion applications. This allows ultrafast processing at up to 80 cm² / sec and high productivity, using power or time sharing concepts. The PowerLine L 400 first introduced at EUPVSEC last year, has since established itself within the Asian market for small size panels. Both lasers feature a “top hat” beam profile to achieve the maximum efficiency per pulse.
The PowerLine SL series is now available as a “ready for integration” package, delivered with all necessary beam optics and an adjustable focus head. Usually installed on moving gantries, this product has demonstrated superior beam and pulse stability in hundreds of installations, specifically for a-Si/μ-Si high volume manufacturing lines.
High Performance Laser Processing from Rofin Fiber Lasers
Manufacturing advanced solar cell concepts such as MWT or EWT cells requires innovative laser concepts. The relatively straightforward automation of laser processing and the low manufacturing costs associated with laser tools continues to promote the use of lasers within the solar cell industry.
Launched at EUPVSEC 2011, Rofin’s new PowerLine F30 Long Pulse fiber laser system
combines high drilling performance on silicon solar cells with the lowest cost of ownership. Using optimum pulse length, high pulse energy and high TEMoo average power, the Rofin PowerLine F30 LP achieves processing speeds better than 1 wafer/sec for trepanning and drilling on MWT cells.
MWT solar cells also require cell edge isolation. Another fiber based product, the Power Line F50 - a 50 Watt unit with pulse frequency up to 200 kHz – is the latest addition to the successful PowerLine F family and achieves best isolation values with processing speeds of up to 1 m/s.
Laser Welding of Cell/Module Connections
Today, contact-free infrared, hot air or laser soldering processes are used to connect tin-plated copper ribbons in solar module assembly. Now, the fast and reliable bi-wavelength copper welding process opens up new possibilities for flexible assembly of standard and back contact cells. The laser welding process, in combination with a pre-patterned copper foil, is a very attractive joining process, especially for MWT / EWT cells. In this way arbitrary interconnection patterns become an option avoiding lead (Pb) content and complying with RoHS directives.
Selective Emitter Technology Delivers Greater Cell Efficiency
Rofin and Centrotherm have together successfully developed selective emitter technology using the PowerLine L 100 SHG (532 nm) from ROFIN. This laser- based diffusion process. of the phosphor within the finger and busbar surface of the solar cell, increases the cell efficiency by up to 0.4 %. The combination of ROFIN’s unique laser source, with average power up to 100 Watts, patent pending top hat profile and fast scanning technology has finally paved the way to creating selective emitters in an economically viable way.
The turnkey manufacturing equipment has been operating successfully at several customer sites with a throughput capacity per machine up to 2400 wafers/h. The attractive cost structure together with the relatively minor changes required when compared to a standard production line, means that this process offers an excellent way of improving cell efficiency with selective emitter technology and standard screen printing metallization.