## 4 Technology Roadmap and Limits  
The development of photovoltaics in coming years will be associated with a continuing shift to the production of PV modules with higher efficiency and durability, while maintaining (or reducing) the price. Crystalline silicon modules will remain the mainstay of technology. In terms of efficiency and price, thin-film modules can compete with them, and intensive development and research is occurring in the field of perovskite technologies.  
In the family of new technologies, the most promising are hybrid organic-inorganic metal halide perovskites. Due to their high efficiency (above 25% on laboratory cell samples [52]) and low manufacturing costs, perovskite solar cells have a great potential to become one of the leading technologies in the PV industry. Recently, perovskite structures approached pilot line production for both flexible modular roll-to-roll lines [53] and silicon-perovskite tandem lines [54; 55; 56]. A serious problem of perovskite structures was low stability, which has improved significantly, but certain problems persist and hinder the development of this technology, and the service life in field conditions is still not fully satisfactory. Therefore, improving the quality and stability of perovskite modules is still the subject of intensive research and development [57; 58; 59; 60; 61; 62]. In addition to the problem of perovskite stability, technology needs to be improved to achieve technological sophistication in large-scale production.  
As stated, thin film (CdTe, CIGS) technologies are limited in production due to limits in material sources [20]. Crystalline silicon cells and modules are expected to continue in their \"work horse\" position. Through technology development, the effective use of starting polycrystalline silicon material was achieved, as demonstrated in Figure 16, and the energy return on investment (EROI) of PV systems with PERC modules is higher than 15, worldwide [10].  
Although the impact of increasing efficiency, reducing prices, and extending the life of PV modules on the LCOE is gradually decreasing (see Section 2), photovoltaic systems are considered a very important part of the future energy sector [63]. Some scenarios expect the PV module's annual production to be over 1 TW\({}_{\text{p}}\) after 2030 [27]. In some scenarios, a technological transition from P-type to N-type starting wafers [26; 27; 31; 64] is expected. This transition could increase the efficiency of the modules from 20% to 23%, which may reduce (calculated according to Equation (5)) the area-dependent investment costs by 8.7%, which may be particularly interesting for projects with a high share of area-dependent costs. On the other hand, an increase in efficiency could also be realized by P-type TOPCon technology [40], which could be less expensive to invest in.  
The current increase in the cost of the construction materials of PV systems (copper, iron, aluminium, etc.) increases the area-related costs, and thus improves the conditions for the use of PV modules with higher efficiency in new projects.  
However, there may be certain material limits that affect this development. The limits in material resources have been discussed in detail in [64]. Resources limit not only the multi-GW scale production of CIGS, but also all types of PV cells using ITO contact layers. Another scarce material used in photovoltaic technologies is silver. Silver consumption for TOPCon cells is 50% higher than for PERC cells; for HJT cells, it is 100% higher than for PERC cells. The increase in the price of scarce materials may slow down the transition from PERC to TOPCon and HJT technologies.  
The sources of bismuth used in low temperature soldering in HJT modules are also relatively limited. With the massive expansion of production, it will be necessary to reduce the specific consumption of these materials, or to develop technologies that will replace these rare materials with more affordable ones.