A comeback for Europe’s solar industry?
A comeback for Europe’s solar industry?
Uwe Rau is Director of the Institute ofEnergy and Climate Research, active in the Photovoltaics section, and professor at RWTH Aachen University. He has been researching solar cells for over 25 years.
In 2012, eight of the world’s ten largest photovoltaic companies were from Germany. Today, there is no German solar cell producer among the top 30. The competition from China in particular has prevailed in the price war. There is now hope for a renaissance in Europe, however. Photovoltaics expert Prof. Uwe Rau explains the background in an interview.
Prof. Rau, what is it that raises hope for a renaissance in European photovoltaic production?
We are on the verge of transitioning to a new level of technology. Some compare this to the transition from 4G to 5G in mobile communications. New types of solar cells are expected to come onto the market soon, such as silicon heterojunction solar cells – SHJ solar cells for short (see infobox) – or a variant of them, the IBC-SHJ. They offer a higher degree of efficiency as an advantage. Plus, Europe is ahead of the game here. An IBC-SHJ solar cell developed in the EU project NEXTBASE, which our institute coordinated, achieves an efficiency of up to 25.4 per cent. This is almost 3 per cent more than commercially available PERC cells, which convert sunlight into electricity with an efficiency of around 22.5 per cent. Moreover, we developed an industrially producible SHJ solar cell at Forschungszentrum Jülich that reaches 24.5 per cent.
Picture above: Uwe Rau is Director of the Institute ofEnergy and Climate Research, active in the Photovoltaics section, and professor at RWTH Aachen University. He has been researching solar cells for over 25 years.
How can some 3 per cent efficiency make a big difference?
With solar cells, it’s all about how much electricity they generate per surface area. In Germany in particular, the space needed for the modules is limited and very expensive. In addition to that, highly efficient cells can significantly reduce the cost of the electricity generated.
Are there any concrete plans to use the new technologies?
The partners in the NEXTBASE project have also developed manufacturing processes for the new solar cell that are suitable for industrial mass production. One of the industrial partners in NEXTBASE, Swiss company Meyer Burger, has announced they will start producing SHJ solar cells and modules “Made in Europe” this year at their German sites in Freiberg and the Thalheim district of Bitterfeld-Wolfen. The company is also already developing the production technology for IBC-SHJ cells. Another, even more efficient technology is also waiting in the wings: the tandem solar cell. Here, a second cell – made of perovskite, for example – is stacked on top of the silicon cell. The company Oxford PV is currently building a corresponding production line in Brandenburg, which is scheduled to start full operation in early 2023. The production technology for manufacturing the tandem solar cell and the underlying silicon cell also comes from Meyer Burger.
66 per cent of all solar modules worldwide come from China, 18 per cent from other Asian countries, 4 per cent from Europe.
Source: Fraunhofer Institute for Solar Energy Systems ISE, Photovoltaics Report, 2020
Can the new modules from Europe keep up in terms of price?
The costs of industrial production of the new modules will probably be in a range similar to the production costs of today’s commercially available PERC modules, which are mainly manufactured in Asia. So Europe could get back into manufacturing here. This would also make sense from an economic-political perspective.
If we have production lines on a relevant scale again, research in Europe can increasingly drive further developments in this field. What’s more, an independent European value chain would minimise dependencies and risks.
Does it matter whether electricity in Germany, for example, is generated by modules from China or from Europe?
As a matter of fact, China currently dominates the world market with low-cost modules. The electricity generated by these modules is of course the same as that of a module from Europe. For the energy transition, however, solar power systems with a total output of several gigawatts will have to be installed every year in Germany alone. Therefore, the technology is of major importance and involves huge investments. Production in Europe would ensure that alternatives are always available on the world market. For example, the corona pandemic has also affected the supply chains of the solar industry: deliveries have been delayed and have become more expensive. Political or economic conflicts could lead to bottlenecks as well.
The interview was conducted by Frank Frick
Types of solar cells
“Passivated Emitter and Rear Cells” are the current standard for solar cells made of crystalline silicon. A special layer on the back of the module reflects mainly red light, which remained unused in earlier modules. The light can thus generate electricity in a second run and improves efficiency.
In the silicon heterojunction solar cell, a monocrystalline silicon wafer is coated by ultra-thin layers of disordered silicon atoms. On the surfaces of the wafer, these layers inhibit the rapid reunification of negative and positive charge carriers, which were separated by the solar energy.
Whereas the current generated in silicon cells, including SHJ, is normally dissipated through electrical contacts on the front and back, the IBC-SHJ cell’s conductive paths are all on the back. As a result, the front is less shaded and the entire surface can be used to absorb sunlight.
Silicon perovskite tandem cell
While silicon captures light mainly in the red and infrared range, perovskite materials are mainly receptive to blue and green light. With a cell tandem of silicon and perovskite, the entire solar spectrum is thus used, which increases the efficiency (world record at present: 29.5 per cent).
PHOTO: Forschungszentrum Jülich/Sascha Kreklau