MANUFACTURINGLASERS


For isolation and connection scribes high quality beam lasers with precise beam conformation and different wavelengths and increasing pulse frequencies must be made available in compact, faster, more flexible and costly effective solutions


size of the BIPV market is small when compared to the necessary investment, the incorporation of laser for this purpose is difficult to be justified from investment point of view.


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Other technical challenges that laser manufacturers consider include laser beam quality, power stability, variations in beam pointing, registration errors in the moving mechanism. There is also the initial investment for PV manufacturers to consider as well as the possibility of tool retrofitting and the speed to volume ramp-up. At present there are not many early adopters of laser technology in manufacturing but many signs point to 2011 being the year of change.


Lighting the next wave


The laser market for PV applications is dynamic and advances in beam and power supply, lasers are becoming more popular in 24/7 industrial operations. This is especially true with the use of ultra short pulse lasers that promise a minimum heat affected zone and less thermal damage in the processed material, e.g. the structuring of the absorber layer in thin film solar cells without damaging the front contact layer underneath.


While picoseconds lasers are already well established in industrial environments,


femtosecond lasers have yet to prove their reliability and stability over time although the additional benefit that femtosecond pulses can provide are obvious and the affordability of these lasers has also improved compared to picoseconds lasers. Femtosecond lasers have been used for research and refractive laser eye surgery for many years but the technology is as recent addition to the manufacturer’s arsenal.


These lasers have potential due to the level of precision and selectivity in applications like thin- film structuring and ablation of dielectric layers. Femtosecond lasers process materials faster than energy can diffuse within the atomic lattice so there is almost zero energy diffusion to the surrounding medium.


Although laser technology has been in use in other industries for many years, lasers in photovoltaic production are still in the introduction phase. As a result, there is plenty of room for improvement and development of processes. In general, product improvement in PV is a very slow process. It needs to be proven in a lab before it will be introduced into production. In some new cell concepts that are tested in the lab today some new and innovative laser processes are used. These laser sources are not ready yet for 24/7 operation. Most of the new opportunities for PV manufacturing will come from using lasers working on special wavelengths, which is important for selectivity of processes. Increased mean laser power and repetition rate offer new possibility to increase process speed. But full benefit requires advances in beam guiding technique (high speed galvoscanners, beam splitting techniques for parallel processing).


Anything that increases the demand and unit volume of lasers shipped each year helps make lasers more affordable in other applications. In this respect the greater demand for lasers for solar manufacturing will help drive costs down and increase availability in other sectors. Subsequent demand in other sectors will help sell lasers in solar. Over time prices will gradually decline and new products will arrive that are more robust and with a higher performance than the previous generation. This migration doesn’t happen if the market is limited to only the high end, such as for university R&D labs. The existence of the market is the driving force. The migration to lower prices and higher performances is a gradual process.


There has been development of back-contact processes developed at the Energy Research Centre of the Netherlands which minimizes


www.solar-pv-management.com Issue I 2011


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