The last months have confirmed the willing of the photovoltaic (PV) industry to continue its impressive growth. Our database (figure 1) count more than 400 plants in production or beginning before 2011. Many emerging companies have been identified with the major part in thin films. Decreasing the production cost is still the main challenge for PV manufacturers, thus we review some of the main issues and describe the current cost situation.

Figure 1: Yole’s PV database sample. (more than 400 fabs covering the value chain
from silicon to module manufacturing)

• Balance on the last months

Figure 2: Yole’s Forecat of the photovoltaic market
with a breakdown per technology

Silicon shortage consequences are a limitation of investments in the main segment (wafer based solar cells) and an increase of the industrialization of PV thin films. According to our database build on a daily survey of the domain, we now count more than 40 companies in a-Si and µ-Si technology, more than 10 in CdTe (PrimeStar, Matsushita Battery, Golden Photon, Calyxo…) and more than 30 in CI(G)S (Ascent, CIS Solar, Heliovolt, Johanna Solar, Solyndra…). This explosion of new entrants is due to the willing to cut manufacturing costs. On a-Si technology, most of the new plants will be build by turnkey equipment suppliers such as Oerlikon, Applied Materials but also Ulvac. In CI(G)S and CdTe technologies, home maid equipments are preferred but Veeco recently introduced a new thermal deposition line “PV-Series SUMO® and VALVED” dedicated to CI(G)S manufacturing. On the III-V cells side, things are also going very fast. Aixtron has sold its AIX 2600G3 IC epitaxy equipments to the Taiwanese WIN Semiconductor. Sharp and Isofoton are rumoured to also invest on this III-V compound field.

• Main issues in PV

Figure 3: Segmentation of the photovoltaic technologies
with their substrates

Same as all energy sources, the most important for the photovoltaic industry is to reduce the cost/Watt peak and more exactly the cost/kWh of solar cells. This cost reduction will pass through a long chain of innovation where solutions would have to be found in order to reach the main goal: make PV a competitive energy with no need of incentives.

From a technical point of view, this cost reduction will be reached while solving the main technical issues.

Through our marketing and technology studies, we have been identifying many issues in the manufacturing processes of solar cells.
         Metallization: Screen printing is the most used method for contact deposition. But, because of wafers going thinner and a trend to increase purity and conductivity of the contacts, new methods are now emerging: inkjet deposition and electroplating.
         Use of Cadmium: because of its toxicity, manufacturers try to avoid the use of cadmium both in contacts of wafer based solar cells and in buffer layers of thin films.
         Shortage of materials: Silicon shortage is well known on the PV market and was hardly slowing the growth on this last years. According to our analysis, situation is now going better but Silicon is still missing to run plants at 100% of their capacity. But, Silicon is not the only shortage we should be aware of Indium, Cadmium and many other materials will have difficulties to follow the growth of the PV industry.
         Metrology tools: now that processes are becoming stables; PV manufacturers are more and more looking to quality and yield improvements. As it is the case in the semiconductor industry, metrology and monitoring tools are a solution to increase the quality of the products and avoid discard. Then, thickness of layers, micro-cracks, shunts… many parameters have to be checked in order to eliminate the defects of a solar cell/module. Moreover, certifications of solar products are being set up and PV manufacturers will have to provide more and more technical information on their products in order to respect labels and norms. 

The listed issues above are just a glimpse of the high number of challenges that PV manufacturers have to face.

• Manufacturing cost analysis:

Figure 4: Manufacturing cost comparison between
polycrystalline Silicon (c-Si), Amorphous Silicon (a-Si)
and Copper Indium Gallium di-Sellenide (CIGS).

Figure 4 is an output of a simulation we run for a 100MW plant through our cost model tool. Results clearly show the difference of manufacturing cost between wafer based technologies and thin films. For a 100MW plant from wafer to module, our simulation gave a manufacturing cost of 1.83€/Wp for polycrystalline Silicon (including staff, equipments, clean rooms and materials). For the same plant, a-Si technology manufacturing cost reaches 1.3€/Wp and CIGS technology reaches 0.9€/Wp.
The higher price of the c-Si technology in comparison with thin films is mainly due to the cost of Silicon. Today the price of the wafer (0.8€/Wp) is more than 50% of the manufacturing cost of a module. The end of the shortage and the Silicon price reduction will create a strong leverage on manufacturing costs.
Manufacturing of a-Si panels is done through PECVD equipments, these deposition methods are more expensive than the evaporation methods used for CIGS deposition.
If on figure 3 c-Si is the most expensive technology it is also the most stable process. Other thin film technologies need more time to optimize their process and improve their production stability.

• Conclusion

Even if a large number of companies are being created and global production volume is increasing, PV industry needs technological solutions for many issues. At Yole we believe these solutions might exist in the semiconductor industry but equipment and material manufacturers need to be informed of the needs of PV manufacturers.

• About the author:

Yole Développement (www.yole.fr) is a market research and strategy consulting company covering the following fields: MEMS, coumpound Semiconductor, Microfluidic, 3D IC, Nano materials and Photovoltaic.
For more information on our PV activities, please contact Gaetan Rull (rull@yole.fr) who is headed the Photovoltaic division.
After the PVTEAM report released May 2007, Yole releases its PV database in October 2007. This data base cover all the value chain with more than 400 companies and has been build on demand of our customer to have an operational tool for improving their network in the PV industry.