Roadmap 1
Silicon PV Modules
Rationale for support
Although China dominates the manufacturing of wafer based silicon solar cells and modules, Europe is a leader in the more advanced technology concepts, both single-junction as well as multi-junction approaches (see Roadmap 4: Tandem PV modules). In particular, Europe’s silicon PV sector (R&D and industry) has proven in the last decade that it can successfully bring novel technologies from the lab to the production environment, leading to higher module efficiencies and lower module costs. Contin- ued R&D effort across the European value chain is impera- tive to maintain this leading position in silicon photovoltaics.
Achieving multi-GWp silicon cell and module manufacturing with low carbon footprint and circularity in Europe
Further lowering the LCoE of both utility-scale PV and Integrated PV
Status
As the global PV market has steadily increased, crystalline silicon technologies have remained the workhorse of the photovoltaic industry, accounting for 90 % of PV installed in the last 20 years.
The efficiency of commercial silicon PV modules has ap- proximately been doubled since 2000 and prices have fall- en by more than a factor of 20. These factors resulted in very low LCoE of 10 (Middle East)-50 (Germany )€/MWh.
Targets, Type of Activity and TRL
There remains huge potential for further innovation in performance, integration and sustainability enabling large- scale deployment, including the use of high-efficiency sili- con PV as a bottom cell in hybrid tandem structures. That will allow efficiencies of over 30 % to be reached in the near future in hybrid tandem structures, and of over 40 % for multi-junction devices (see Roadmap 4).
Till 2030 different actions are needed to establish the tar- gets from feedstock, over wafer and cells to modules:
Low-cost, high-quality silicon feedstock, ingots and wafers
Material and process development for direct band- gap silicon films enabling high conversion efficiencies
Efficient processes for low-cost crystal pulling of high-quality ingots with large diameters suitable for G12 (210 mm length) or larger wafers that allow for higher level of automation (industry 4.0 including digitalisation). Development of new knowledge and processes for low oxygen and other impurities, high minority carrier lifetime, and mitigating degrada- tion effects such as Light and elevated Temperature Induced Degradation.
Advanced processes for multi wire wafering of large (G12 and larger) thin (<130µm) wafers at low cost and with high final yield and final efficiency in the module. Development of automatic handling pro- cesses.
Processes and technologies supporting cast-mono and high-performance multi-crystalline Si wafers such as gettering and improved casting methods.
Process and equipment development for epitaxial wafers and alternatives (kerf-free);
Reduction of cost, energy consumption, and other factors negatively impacting sustainability (e.g. wa- ter usage and CO2 emissions from all stages includ- ing quartz reduction and production of high purity silicon feedstock). Of special interest here are epi- taxial wafers and foils and other kerf-free technol- ogies, and also the purification through the metal- lurgical route.
Efficient and low-cost processes for recycling of Si from end of use and kerf from multiwire wafering.
Efficient recycling process for silicon off-cut in ingot manufacturing (such as ingot tops, tails, side-cuts and off-spec material).
Further development and supporting processes for diamond-wire cutting of multi-crystalline wafers in order to save material (reduce kerf loss), process time and cost. E.g., nanoscale texturing for dia- mond-wire cut surfaces.
Development of technologies for ingot pulling min- imizing oxygen related stacking faults resulting in high overall yield over the ingot and high-quality n-type wafers and therefore a narrow efficiency dis- tribution after cell processing.
Advanced silicon cell and module technologies
Process and material development for down and up conversion layers, or equivalents, as alternatives for tandems and enabling beyond 30 % conversion efficiency
Nanophotonic structures to maximize absorption in ultrathin (<20 um) silicon solar cells enabling re- duced silicon consumption and higher efficiencies (beyond 30 % possible because of high Voc due to higher carrier concentration)
Innovative texturization and light-trapping concepts for thin and ultrathin solar cells
Advanced low-cost surface passivation and novel passivating contacts, novel heterojunctions, etc. (polySi alloyed with C or O; dopant free transparent passivating contacts, amorphous/nc-Si alloyed with C or O; material research, opto-electronic proper- ties); including thin/ultrathin solar cells, and ena- bling >26 % cell efficiency for G12 wafers
Knowledge development of degradation mecha- nisms in modules during heavy stress conditions in the field and mitigation procedures
Development of low stress metallization and in- terconnection technologies for thin/ultrathin solar cells and improved reliability
Technology development for circular design of c-Si based modules, considering sustainability and en- vironmental aspects: energy /water consumption, avoidance of scarce and toxic materials, re-use of components, etc.
- Reduction or replacement of critical raw mate- rials such as silver, indium and fluor to enable sustainable growth of PV. Example: Low-cost and Ag-free metallization including, but not limited to, Cu plating, Fluor free module materials, TCOs using abundant materials (In free), such as AZO. Crucial here is that the novel materials and pro- cesses should not lead to efficiency nor reliability and longevity losses.
- So-called up-cycling (which is actually recycling and maintaining high value; also for Ag and high-value Si)
Development of aesthetical modules (freedom in colour) with maximum loss of 10 % relative com- pared to full black module
Development of 3D-shaped modules enabling inte- grated and customized products
Development of technologies and equipment for highly automated (industry 4.0 including digitalisation, and for tens of GW production facilities) cell and module manufacturing enabling processing of M10 wafers or larger. The solar cells should be based on passivating contacts (polySi or silicon heterojunctions with doped amorphous silicon electron and hole contacts and have >25 % cell efficiency for different cell designs (front and back con- tacted and back-contacted)
Development of improved module technology for higher performance: cut cells (incl. edge passiva- tion), novel interconnection such as shingling or alternatives to maximize packing density / output power, bifacial, back-contacted, design and materi- als for longer operating lifetimes, avoiding/manag- ing local heating in high-power modules
Technology and processes for thin Si cells including excellent passivation, advanced light management, low-stress metallization and interconnection)
Development of light weight modules enabling reduction of system cost
Development of light weight modules enabling reduction of system cost
Development of fluorine-free back sheets for modules that lead to similar module lifetimes as conven- tional back sheets
Development of advanced processes and equipment for low cost and high throughput production of highly efficient and advanced homojunction c-Si cells (for example poly-Si, back-contacted) and modules (for example novel interconnection, high packing density) in GW scale with low material us- age and low energy consumption
Development of improved module technology for heterojunction cells: cutting of cells (including edge passivation), novel interconnection such as shingling or alternatives for high packing density, bifacial, back-contacted, design and materials for longer operating lifetimes, avoiding/managing local heating in high-power modules
KPIs
KPIs that can be utilised for capturing progress in the above identified R&I fields are:
| KPI | Target Value (2030) |
|---|---|
| Manufacturing Capacity | 100 GWp silicon-based cell and module manufacturing capacity with low carbon footprint in Europe |
| Performance and Sustainability | High-performance and sustainable PV with LCoE of 25 €/MWh at medium irradiation levels of 1300 kWh/(m2a), e.g. in southern Germany for utili- ty-scale PV and <50 €/MWh for ‘Integrated Photovoltaic’ elements (4) European players as world leaders regarding high performance and sustain- able silicon PV technology and its integration in the environment.
|
| Supply | Ensure the supply of critical raw materials like silver to a multi-terawatt in- dustry. |