Light at the end of the tunnel

Singulus Technologies presented a new PV tool that enables the production of the back side of the so-called PERC solar cells. Additionally this tool is said to be able to produce a higher efficiency cell than the standard cells available at the moment. Stefan Rinck, President and CEO of Singulus Technologies, sat down with pv magazine to talk about the market for photovoltaic equipment manufacturers and this new tool.

The exhibitor numbers at the EU PVSEC has become significantly smaller. What is your perception of the market situation?

Rinck: We have had two difficult years behind us as everyone knows, but we see light at the end of the tunnel. We are receiving many queries about our new developments, for example the PERC upgrade concept, where we passivate the back side of wafers with aluminum oxide and thereafter, silicon nitride. Three weeks ago we signed a big contract with an important client for this technology. The Chinese company M-Cells wants to buy a total of 16 machines. This is something very important for our company. This is a first significant success step in Asia, with more to come. At the moment there are many manufacturers who are interested in increasing their efficiency gains to more than one percent, something possible with this concept.

What do the 16 machines translate to in terms of annual production capacity in MW?

Rinck: One machine has an average of a little over 30 MW annually. 16 machines would be around 500 MW.

The contract is from Asia. The European manufacturers on the other hand are struggling. Can you live with that?

Rinck: That is definitely, for us, not alright. This needs to be made clear. We do wish that our domestic solar industry will perform better as we need our clients in Europe. We need the continuous supply-chain. Our clients in Europe are near and dear to us. Hence we are in close contact with them. But we also work with our Asian clients who have decided on our PERC technology at the moment and are investing.

You require manufacturers who aid you in the development of the new generation and provide you with contracts. This has been the role of European manufacturers thus far. Can Asian manufacturers take over this role?

Rinck: We worked very closely with German research institutes to develop this new technology and bring it to maturity. That was very crucial to us and a worthy process. We can now offer this process worldwide. But that is just one example. There are still numerous improvements to be made, and we work with research institutes on these processes. Therefore we need the domestic industry. It would be possible for us to develop further essential innovations in the solar industry only in a community made up of European manufacturers, machine makers, and equipment producers as well as research facilities.

How is the development process of the PERC technology?

Rinck: The core is a PECVD machine, a Plasma Enhanced Chemical Vapour Deposition. With this we apply, in a vacuum, under different steps, firstly aluminum oxide for passivation of the back side and thereafter silicon nitride. The back side is thereby completely processed in a single machine, and only has to be opened with a laser at the points where the cell is to be contacted.

What was the challenge in this process?

Rinck: The challenge is handling the pre-cursor gases, the gases that react to the plasma chemically and thereby form a layer on the cells. For example, TMAL for the generation of aluminum oxide. That is a challenge in itself as the gas that gets formed can spontaneously combust in air and reacts explosively with water, which in turn called for high safety precautions within the machine.

Another challenge was to develop a machine that is able to deposit very homogenous layers. And in the end what is important are the efficiency gains that can be achieved with this process. We worked very closely with research institutes on this development. They have supported us in the scientific aspects, to develop better layer properties and eventually to attain efficiency gains of partly more than 1%.

There are other methods as well, with which PERC cells can be developed. For example, Atomic Layer Deposition or ALD. One can see at this trade fair as well that this is also moving on to industrial scale. Is your process better?

Rinck: ALD is for sure an interesting process for back side passivation to deposit aluminum oxide. The disadvantage is that there is still a need for a second machine to deposit the silicon nitride. That means there is a need for two steps and two machines. In the machine that we have developed, all processes take place together in one machine in a vacuum without any interruption. With this our production process is easier to implement industrially. Moreover passivation and layering done in a plasma provide better layer properties.

The PERC technology is riding on an industrial wave at the moment, with the expectance of larger scale implementation. What is to come?

Rinck: There are quite a number of technologies in discussion, on which we are intensively working on. One is the transition from P-type to N-type wafers. With N-type wafers it is recommended to deposit aluminum oxide on the front side of the wafers. That can be realised with our machine. Additionally there is the discussion and working group at the moment over how HIT cells and IBC cells can be industrially processed in a practical manner. For that we are also developing a suitable layering system, that can also be coupled with our SINGULAR XP.

Translated and edited by Shamsiah Ali-Oettinger