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CPV goes big time - solar interview with Hansjörg Lerchenmüller of Soitec on scaling up, competition with other technologies and Soitec's global developments

Hansjörg Lerchenmüller
Hansjörg Lerchenmüller

Hansjörg Lerchenmüller is a Senior Vice President of Soitec's Customer Group, in charge of the company's Solar Energy Business Unit, including its Concentrix concentrating photovoltaic (CPV) solutions. This technology has been chosen for 305 MW of power purchase agreements (PPAs) with San Diego Gas and Electric Company (SDG&E) in March, April and May 2011, which will represent a far larger application of CPV technology than any currently commissioned project.

Mr. Lerchenmüller has been central to the development of the Concentrix CPV system. He founded Concentrix Solar in 2005, brought investors on board and led the Concentrix technology from laboratory scale to a commercial product with a 25 MW production line. Mr. Lerchenmüller also supported Soitec's acquisition of Concentrix in 2009.

Before founding Concentrix, Mr. Lerchenmüller worked for ten years in technology management at the Fraunhofer Institute for Solar Energy Systems ISE where he built up and managed the Marketing Network of Fraunhofer for six years. Mr. Lerchenmüller's duties at Fraunhofer ISE included coordination of solar power plant activities.

He was among the initiators of the CPV Consortium, a globally acting industry organization. Since its formation in 2008 Mr. Lerchenmüller is a Member of the Board of Directors.

The following interview was conducted on July 12th, 2011 by Solar Server International Correspondent Christian Roselund at Intersolar North America 2011 in San Francisco.


Solar Server: Congratulations on your recent PPAs with SDG&E. I note that these PPAs are two orders of magnitude larger than any CPV plant in existence. What is it that you think inspired SDG&E to make such a bold move into CPV?

Hansjörg Lerchenmüller: That has to do with the technology itself, the performance of the technology. CPV really performs impressively well in a climate which is like the desert climate in the Imperial Valley. And all these plants will be located in the Imperial Valley. Which is where the technology just performs best due to the hot temperatures and due to the production profile.

The production of CPV with a broad shoulder, produces energy, basically, from sunrise to sunset. That is a key advantage to a utility, because it will be producing energy when it is needed most: in summer during day time when it is hot. That is exactly when the load curves are peaking due to air conditioning. And this is very important for the utilities.

And you mentioned that it is by far larger than any other CPV plant, but given the fact that CPV is a module technology, the pure technical challenge to go from one megawatt to 100 megawatts is close to zero - the technical challenge. There is a logistical challenge, but this is also one of the key challenges for any utility scale photovoltaic power plant, but technically it is just 100 times more trackers.

Tracking technology by Soitec
Tracking technology by Soitec

Anyway, you have building blocks, so when you work with large plants, you build it out in so-called building blocks, of one megawatt or two megawatts. And then a large plant is just a replication of one building block, another building block, another building block. You can have three or four teams working on the same land, on the same power plant. And then a 100 MW plant will be built over 20 months, 24 months.

So you just do it step-by-step, and the challenge is the logistics. Like with all PV power plants, if you install 100 MW with silicon solar modules, you had better take care of the logistics.


Solar Server: Has the final location been selected for your CPV factory in San Diego?

Hansjörg Lerchenmüller: Not yet. We are in final stage, we short-listed a few sites, and we will make the decision soon, and will communicate it still this summer.


Solar Server: Can you talk a little about the levelized cost of energy (LCOE) projections for CPV, and the specific advantages of this technology?

Hansjörg Lerchenmüller: The current level of LCOE is in the range of 12 to 14 cents, that's where you need to be to be competitive.

What is probably one of the biggest advantages of CPV, is that the technology is very, very simple. Our specific design is very simple. We use just a lens plate, and a bottom plate, and we have the bare die, just the cell mounted on the heat sink. Putting this together allows for a very simple design. So you have the lens, the cell and the heat sink. And that's it.

At the same time, the efficiency of these modules is twice as high as a standard silicon solar module. Which means that we take twice as efficient use of the glass, of the installation, of everything. So that helps a lot with the cost efficiency, it helps a lot to cut costs.

CPV cell
CPV cell

Solar Server:  I note that Soitec has signed an MOU to partner with MASEN in Morocco. Can you talk about the next steps for this collaboration?

Hansjörg Lerchenmüller: For us, the MENA region is very important, as with the proximity to Europe, Northern Africa is almost like a home market for us. We really appreciate that we can work with MASEN. MASEN is a very visionary and ambitious player in Morocco, they want to do 2 GW of solar, until 2020. So we are really enthusiastic about working with them.

We signed an MOU with them which has various components. The first one is the installation of 10 MW of CPV in two stages. The first stage is a 5 MW to be installed early next year, and the second will come in a later stage with an even more sophisticated technology.

And there are other elements of the collaboration, like an R&D collaboration. It is part of our strategy to involve local partners, so we will work on R&D, and we will also work on the supply chain side with MASEN, to see what components of the system, on top of the installation, which will of course be local, can be provided locally. And that goes even as far as we will be looking into local manufacturing.

Because if you look at the region, we believe that there is easily room for 100 or more than 100 megawatts a year of CPV in that region. We have plenty of sun, we have strong growth of electricity need. And we have also good industrial experience, and experience how to perform civil works. So we really believe that there is a big future for CPV in the region.

Just a week ago, we installed a demo tracker in Tunisia. So we are not not only working with Morocco. It's one small system, but that's the beautiful thing with CPV. It's modular; you can install demo installations and you can show it to everybody. And everybody is impressed, of course, by the high efficiencies.

Solar Server: So there is also an MOU signed with the Tunisian Power Authority?

Hansjörg Lerchenmüller: That's with the Tunisian utility and with CEA. We are working on power storage solutions on this deal. So it is more an R&D collaboration, involving CEA, which is a French R&D organization, working on batteries and on other kinds of storage solutions as well. We will be testing storage solutions based on this one. For the day after tomorrow, storage will become a big feature for CPV power plants, and for PV power plants in general.


Solar Server: I've noticed that there are three main CPV companies that have installed any substantial capacity. What are the specific advantages that Soitec and its Concentrix technology has, and what are you strategies for competing in the CPV space?

Hansjörg Lerchenmüller: Why we are so convinced of this technological approach, is that it is really based on a very, very simple setup and a technological approach, with the principle: "Make it simple and keep it cheap".

We have just the lens plate, the bare die and the heat sink. And that in terms of manufacturing is just very, very easy to drive down the cost. None of these materials, it is very important to note, are expensive materials. So we are using glass as the top plate, which includes a very thin layer of silicone, it's not expensive. And then we have the cell and the heat sink, and the back glass plate.

So that's the most simple and straightforward approach you can have. At the same time, we are reaching today 28%, and by the end of the year 30% module efficiency out of these modules. So that combination of simple bill of materials and high efficiency, that really provides for a cost advantage.

Soitec CPV tracking system
Soitec CPV tracking system

We are also working on a cell development, and incorporating Smart Cut technology for CPV. Smart Cut technology is the transfer of very thin semiconductor layers, with an atomic scalpel. So we are able to peel off very thin layers of semiconductor materials from the wafers, and stick it on other substrates. And that way we can produce triple-junction solar cells, which will be more efficient than any other triple junction solar cells. We are aiming at 50% cell efficiency by the year 2014, 2015.

Today we're buying the cells, like everybody. But tomorrow we will build our own cells.

And on top of that, the materials that we are using are all completely stable materials, so in terms of long-term durability there is no reason why the module will degrade at all.


Solar Server: I understand that Soitec is part of DESERTEC. Have there been any recent developments with the DESERTEC plan?

Hansjörg Lerchenmüller: The DESERTEC industrial initiative is now proposing a reference project, where 500 megawatts of CSP and different technologies of different PV technologies including CPV are supposed to be installed in Northern Africa, with the sale of the electricity to Europe.

We talked about the competition between CPV, and we might want to talk about the competition with CSP as well.

CSP, from our point of view, will only be used in certain market circumstances, where the customer really, really needs to have storage. And the customer will have to pay for the storage, because CSP is more expensive than CPV. So the question will be, how much will the customer, the utility be willing to pay for the storage.


Solar Server: So you feel that you can beat CSP on an LCOE basis, that is what this comes down to.

Hansjörg Lerchenmüller: We already did it. At this point in time, CPV is less expensive than CSP. And the further cost reduction potential of CPV goes much further, and faster.

Again, the huge advantage of CSP is the storage, so I definitely see there will be mix of several technologies. If you put a 250 MW plant in one place, a sudden bad weather front can put a big challenge to the grid.

If you distribute those plants over an area of 100 kilometers, then it is getting already much less challenging for the grid. So there are other ways to handle the intermittency, other than choosing CSP with storage.