In this section, we described the various device architectures in production for crystalline-silicon PV as well as the various absorber materials being used and developed for thin-film PV. We also explained why multijunction PV technology is considered the future of PV technology. We identified four major technological challenges (Fig. 1) for future mass production and deployment of PV technology in order to achieve the goal of climate neutrality and indicated how optics could help resolve these challenges. The four main challenges (Fig. 1) are: • Sustainable production of PV systems; • Higher energy conversion efficiencies; • Higher energy output and operational lifetime; • Integration of PV systems in their environment.

Policy Highlights To achieve the recommendation stated in the chapter title, we propose the following: bullet Provide an overarching shared definition of Agrivoltaics (AV) with a precise balance between the agriculture and energy components- general enough to guarantee agriculture will be kept as the primary activity but flexible enough to adapt to the specific conditions. bullet Fund further Research and Development (R&D) through pilot projects to investigate different technical configurations and crucial parameters to improve the balance between energy production and farming. bullet Identify an integrated scheme of incentives for AV to prevent agriculture from being abandoned in favour of energy production. bullet Engage with local communities to develop local and national criteria for implementing AV, support the continuation of agricultural activity, raise local awareness, and foster active community involve-ment in AV projects to maximise regional economic benefits and avoid extractivist behaviours. bullet Facilitate the dialogue between Social Sciences and Humanities (SSH) and Science, Technology, Engineering and Maths (STEM) communities by constructing a common definition of the AV policy problems at stake.

The ongoing development of photovoltaics into terawatt scale poses a number of challenges where the optics and photonics communities can contribute. An international consortium recently compiled a roadmap that elaborates on these challenges.

The EU crystalline silicon (c-Si) PV manufacturing industry has faced strong foreign competition in the last decade. To strive in this competitive environment and differentiate itself from the competition, the EU c-Si PV manufacturing industry needs to (1) focus on highly performing c-Si PV technologies, (2) include sustainability by design, and (3) develop differentiated PV module designs for a broad range of PV applications to tap into rapidly growing existing and new markets. This is precisely the aim of the 3.5 years long H2020 funded HighLite project, which started in October 2019 under the work program LC-SC3-RES-15-2019: Increase the competitiveness of the EU PV manufacturing industry. To achieve this goal, the HighLite project focuses on bringing two advanced PV module designs and the related manufacturing solutions to higher technology readiness levels (TRL). The first module design aims to combine the benefits of n-type silicon heterojunction (SHJ) cells (high efficiency and bifaciality potential, improved sustainability, rapidly growing supply chain in the EU) with the ones of shingle assembly (higher packing density, improved modularity, and excellent aesthetics). The second module design is based on the assembly of low-cost industrial interdigitated back-contact (IBC) cells cut in half or smaller, which is interesting to improve module efficiencies and increase modularity (key for application in buildings, vehicles, etc.). This contribution provides an overview of the key results achieved so far by the HighLite project partners and discusses their relevance to help raise the EU PV industries' competitiveness. We report on promising high-efficiency industrial cell results (24.1% SHJ cell with a shingle layout and 23.9% IBC cell with passivated contacts), novel approaches for high-throughput laser cutting and edge re-passivation, module designs for BAPV, BIPV, and VIPV applications passing extended testing, and first 1-year outdoor monitoring results compared with benchmark products.