Photovoltaic Manufacturing. Группа авторов

Figure 2 NREL chart of the highest confirmed conversion efficiencies for champion modules for a range of photovoltaic technologies, plotted from 1988 to the present. Image by Nikos Kopidakis, National Renewable Energy Laboratory (NREL), Golden, CO, 2021, under public domain.

Despite this impressive progress, the processing of PV still is far from having reached its limits, and new challenges have to be addressed. Emerging developments, such as black silicon, provide a huge potential to make PV even more competitive in the field of energy conversion. Production efficiency requires a minimization of material and process losses, reproducible results, and economic scaling of the technology. The long-term nature of most PV applications and their large-scale implementation increases the importance of recycling. Ideally, this is included as part of the processing and manufacturing strategy.

      The processing of PV today follows well-established standards, but as anyone involved knows, the detailed result will be highly dependent on the local machines and processing steps. Any difference in the settings might make a critical difference in the PV product performance and might distinguish the market leader from its competitors. This book introduces the readers to the theory and practical aspects of solar processing.

      Metal-assisted chemical etching (MacEtch) for black silicon (b-Si) is expected to be the leading solar manufacturing technology in the future. Chapter 1 introduces this micro-/nanofabrication approach as one of the most promising prospects to further reduce the costs of photovoltaic devices while increasing their efficiency. The origin of MacEtch and the underlying mechanism are explained with a special focus on b-Si. The history, the state of the art, and an outlook toward the large-scale deployment in silicon photovoltaic industry are given.

      Chapter 2 introduces the reader to alkaline texturing for the reduction of optical losses in monocrystalline silicon solar cells. The underlying process and the most important factors, parameters, and issues are explained. In addition, the texturing process is located in the whole manufacturing process of the solar cell, highlighting the importance of the previous steps for a high-quality result.

      Chapter 3 provides a detailed introduction to advanced texturing with metal-assisted chemical etching in silicon solar wafers in general. The underlying electrochemical mechanisms are explained. Common methods, typical process steps, and structure characteristics obtained by metal-assisted chemical etching methods are introduced. Examples of the characteristics of topography and anti-reflection of the structures obtained using different metal catalysts and different etchant ratio are discussed.

Wet chemical cleaning of wafer surfaces and the most common cleaning technologies are outlined and discussed regarding their potential in the solar manufacturing process in Chapter 4. The reader is introduced to types and impact of contamination and to the concept of “contamination management.” Examples for this innovative approach are given. The chapter closes with an economic perspective on the topic.

      Reliable quality control, reproducibility, and the development of processing technologies all rely on analytics. Chapter 5 covers impurity analytics for the manufacturing of photovoltaic solar cells. With a special focus on the chemical analysis of silicon wafer surfaces, a detailed description of the analysis of trace metals is given. Current developments in analytical techniques for organic contamination are reviewed, and an overview on recent analytical techniques with application examples is provided.

      This book is a comprehensive review on the most important steps in processing a high-quality solar wafer while keeping track of economic key values. The essential knowledge is explained by recognized experts in their field of endeavor. Outlooks on future topics are given, and recent challenges and innovations are presented. This book provides you with an efficient and solid start to this important field of photovoltaics. The technological limits of photovoltaic are still to be reached—may this compilation help you in exploring them.

      The editor would like to thank Karen Reinhardt for the initial idea and the beginning of this project. I also thank sincerely all the authors for their willingness to share their expertise, their efforts to make their knowledge understandable for a larger audience, and for staying patient and focused during the publishing process of a book in the midst of a pandemic.

       Monika Freunek

      Lighthouse Science Consulting and Technologies, Canada

      June 2021

      References

      1. F. Haase et al., Laser contact openings for local poly-Si-metal contacts enabling 26.1%-efficient POLO-IBC solar cells, Sol. En. Mat. Sol. Cells, 186, November 2018, 184–193.

      2. T. Tiedje et al., Limiting Efficiency of Silicon Solar Cells, IEEE Trans. El. Dev., 31(5), May 194, 711–716.

      3. IEA, https://www.iea.org/data-and-statistics/charts/solar-pv-module-manufacturingand-demand-2014-2020, accessed 21-02-2021.

      4. https://en.wikipedia.org/wiki/Cost_of_electricity_by_source, accessed 21-02-2021.

      5. https://www.pv-magazine.com/2020/04/30/lcoe-from-large-scale-pv-fell-4-to50-per-megawatt-hour-in-six-months/, accessed 21-02-2021.