INTERVIEW with SEBASTIAN SCHINDLER

The solar production in Germany unfortunately has collapsed. Is it still profitable to develop modules in Germany? Which companies benefit from your research? 

In my opinion the solar production didn’t fully collapse. There is still a solar industry in Germany, but a big industry sector with complete value chains, like we had years ago in “Solar Valley” [industrial park in Saxony-Anhalt, in Bitterfeld-Wolfen] for example, is not existing anymore. In comparison to worldwide production capacities, especially in Asia, the production capacity of Germany is certainly marginal.

Research and development is still existent in Germany, especially through institutes like ours. In some areas of the photovoltaic sector there is still a lot of know-how, specifically in cell research and cell efficiency research and also in process technology and system engineering. 

There is a shift along the value chain, because unfortunately a lot of the high-volume mass production has moved. We rather have medium-sized business partners now, like smaller module manufactures and partners in the manufacturing and automation industry, as well as in the field of PV plant planning and system installation.

Where do you see opportunities for entrepreneurship in the solar industry sector?

I think there are entrepreneurial opportunities in the solar industry sector in Germany by all means. The question is rather in which field one can be successful with products, ideas and concepts. The government has set a corridor for expansion which is very low though. I see chances especially in using the insolation potential for photovoltaics on surfaces that are not yet accessible. For example, in the large field of building integration or energy-efficient renovation where you can work with an already existing infrastructure. In these fields I also see a local know-how in Germany and Europe which has potential for new businesses. Eventually we need the expansion of photovoltaics to become independent of coal-based power generation. 

You focus on the development of lightweight modules for a better integration – also beyond architecture. How does the production of lightweight modules differ from regular photovoltaic modules? What kind of difficulties are there in the production? 

The differences between standard and lightweight modules are not the technology of the cell but the material choices for encapsulation of the solar cells and the front and back side of the modules. For example, architectural integration sets other requirements for building integration, so that we replace glass with plastics for overhead installation. That way we are able to produce light, flexible or very rigid formats.

We try to use the features of the standard module technology, the inexpensive and efficient silicon wafer, and integrate them in alternative module stacks and design concepts. We also try to transfer the whole manufacturing process of standard modules to work economically. Difficulties arise through the combination of different materials which makes it challenging to copy the process one to one. 

Are lightweight modules as efficient as regular silicon photovoltaic modules? 

Lightweight modules can be as efficient as conventional glass-backsheet modules which are framed in aluminum. 

How long is the lifespan of new solar modules? 

One must differentiate between product warranty and performance warranty. The product warranty covers a certain level of quality of the module. The performance warranty defines for example that after a lifespan of 10 years there is still 90 percent of the performance available as stated in the data sheet, or 80 percent after 25 years. 

Is it possible to remove and renew integrated solar modules like they are used in your Project C3 or SOLAR.Shell? 

The components of the project C3 are replaceable since there is a bracket system on the back of the cells. The topic of module revisability, especially on buildings, is not fully concluded yet. We are aware that we must think about how to make integrated modules removable and what happens in case of damage. In the field of standard module technology, exchanging modules is working well. It will become far more difficult with integrated solutions in roofs or facades. In my opinion the building industry and solar industry must work in close alliance to develop a “building material photovoltaic module” which can take inspiration from existing interchangeable solutions, like curtain wall systems. 

What are the biggest challenges in the development of integrated solar modules? 

The biggest challenges are surely application-specific solutions in which form, format and formal language differ from standard modules. The specific measurements of the solar cell as the smallest unit need to be considered. One must find a compromise on how to arrange the cells in the best way possible. 

Do integrated solar cells, for example in cars, really contribute to a better climate? Which driving distance does the energy from the roof cover? Or do you fear a rebound effect where the owner will drive rather more because of a green conscience?

I believe that there are several approaches of the automotive industry as to why they want to integrate photovoltaics. There are surely companies like Lightyear who see photovoltaics as an immanent part of vehicle charging and lengthening of reach. Personally, I see PV integration in vehicles for different applications like the infrastructure of the electrical system or additional applications. A classic example could be the PV integration in refrigerated trailers where the cooling compressor runs on electricity only. This would prevent the use of electricity at the expense of reach in electrical or hybrid vehicles. In this I see an improvement of climate impact because the cooling system would be independent from a diesel generator, which would otherwise have to be running for cooling goods. 

While further developing photovoltaic cells is there also research on recyclability of modules? To what extent are the materials separable homogeneously to recover resources? What is practice and what is theoretical? 

There is research for recycling of PV modules and we support a few projects on this matter. But recycling is not my focus at the institute. There is a European recycling platform and take-back agreements of old modules are well defined and documented in respective data sheets by producers or independent platforms like PV CYCLE Modules can be returned there. With regard to resource recovery this is surely not coming from a completely selfless motivation since precious metals can be recovered for example. There is a lot of initiative in the sector regarding recycling and new material utilisation. There is surely a “playground” for research and development, especially with lightweight modules where the compound materials are only plastics, silicon and metals, perhaps these materials are even easier to separate than a module with a glass front. 

Which hopes, wishes and expectations do you have for a university project with the title ‘the power of… where design meets solar energy’? 

I did not get an insight into the project results yet so I’m just excited so be introduced to new ideas and concepts, to get a perspective on different entrepreneurial opportunities in the field. To come up with new topics and applications and to ask “Why isn’t photovoltaic used there? It would make sense there!”.

Photo: Tina Marschner

Sebastian Schindler is team leader for module technology within the group called “module and system reliability” at the Fraunhofer-Center for Silicon Photovoltaics CSP in Halle. The institute conducts applied research in the fields of silicon crystallisation, wafer production, solar cell characterisation and module technology. In doing so they develop new technologies, manufacturing processes and product concepts along the whole value chain of photovoltaics.

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