Key findings of the “International Technology Roadmap for Photovoltaic (ITRPV) 2019 Results” published in April 2020.
With solar power becoming one of the cheapest power sources worldwide, global solar photovoltaic (PV) installations continue to grow at an unprecedented rate. To keep pace with the capacity expansions rapid technology advancements are being made as manufacturers strive for greater market shares. The focus is on developing more efficient and cost-effective products, with new cell and module designs, lesser and cheaper materials and revamping of production lines. With crystalline technology evolving into PERC, bifacial and half-cut cells, the energy production from the solar power plants continue to increase resulting in greater cost-efficiencies.
The present, eleventh edition of the ITRPV was jointly prepared by 57 leading international poly-Si producers, wafer suppliers, c-Si solar cell manufacturers, module manufacturers, PV equipment suppliers, and production material providers, as well as PV research institutes and consultants. The aim of ITRPV is to inform the solar industry about anticipated technology trends in the crystalline silicon (c-Si) based PV industry. Presented below are the key highlights from the report.
Cost considerations
The global c-Si cell and PV module production capacity at the end of 2019 is assumed to have increased to about 200 GWp due to continued PERC capacity expansions. c-Si has a market share of about 95 per cent while thin-film has a share of 5 per cent. The PV module market in 2019 increased by about 20 per cent to 130 GWp. The c-Si module market shifted significantly to mono-Si based products. The increased mono-Si wafer and cell capacity resulted in price reductions for mono-Si and a significant price decline for multi crystalline-Si (mc-Si) based products. The spot market price for mono-Si and mc-Si modules respectively fell during 2019 only by about 10 per cent while the corresponding cell prices dropped by 20 per cent in the same time frame. The average module prices are calculated for January 2018, January 2019, and January 2020 for mono-Si modules to 0.39, 0.26, and 0.24 $/Wp and for mc-Si modules to 0.31, 0.23, and 0.21 $/Wp respectively.
While the wafer prices for mono-Si wafers stayed quite stable, prices for mc-Si wafers suffered from a continued price decline mainly due to the shrinking market share. Prices for mc-Si cells followed this trend and dropped by about 25 per cent during 2019. Mono-Si cell prices also dropped by 25 per cent in 2019 in contrast to the stable mono-Si wafer prices. So, the increased price for the modules is caused due to the introduction of larger wafer formats. This in turn results in higher module powers at the expense of higher material cost for the larger modules. The non-silicon module manufacturing costs are mainly driven by consumables and materials.
Taken into account the fact that the anticipated global PV module production capacity of more than 200 GWp in 2019 will further increase in 2020 due to continued capacity expansions, the production capacity will not at all meet the predicted global market demand of 142 GWp in 2020 but will again exceed it. Therefore, prices will not compensate for any cost increases as there is no shortage expected. In other words, the pressure on wafer, cell and on module manufacturing will persist unchanged. Achieving cost reductions in consumables, and materials will be more difficult but must be continued. Improving productivity and product performance will stay in the focus resulting in further pressure on older, depreciated manufacturing lines.
Cell materials and processes
Metallisation pastes or inks containing silver (Ag) and aluminum (Al) are the most process-critical and most expensive non-silicon materials used in current c-Si cell technologies. Paste consumption therefore needs to be reduced. The reduction of remaining silver per cell is expected to continue during the next years. The current study found 100 mg as the median value for 2019 and 90 mg for 2020, revealing that there was no big progress in laydown reduction. Anyhow, a reduction down to 50 mg per cell is still expected to be possible within the next 10 years. New developments in pastes and screens must enable this reduction, and this clearly shows the necessity of a close collaboration between suppliers and cell manufacturers to meet these challenges. N-type cell concepts show a significant higher silver consumption than p-type cells as silver is used for front and entire rear side metallisation. Bifacial p-type concepts cause no difference in silver consumption. Because silver will remain expensive due to the world market dependency, it is extremely important to continue all efforts to lower silver consumption as a means of achieving further cost reductions. Despite a continuous reduction of silver consumption at the cell manufacturing level, silver replacement is still considered. Copper (Cu), as less expensive material, applied with plating technologies, is the envisioned substitute, today in use only for high efficiency back contact cell concepts.
The first production process in cell manufacturing is texturing. Reducing the reflectivity is mandatory to optimise cell efficiency. Acidic texturing, a wet chemical process, is mainstream in current mc-Si cell production. Wet chemical processing is a very efficient and cost optimized process especially due to its high throughput potential. Standard acidic texturing including the use of additives is expected to stay mainstream until 2024. Especially the application of additives enabled good texturing of DWS mc-Si material. Progress in metal catalyzed chemical etching (MCCE) or wet chemical nano-texturing technologies is causing the expectation that MCCE will become dominant after 2024. Reactive ion etching (RIE) is not expected to reach > 2 per cent market share due to the higher costs.
Since 2012, several cell concepts using rear side passivation with dielectric layer stacks have been in mass production (PERC/PERT/PERL technology). Remote plasma PECVD Al2O3 in combination with a capping layer has a market share of 55 per cent in 2020. This former mainstream technology for PERC cell concepts will further lose market share. Newly built cell production capacities will use ALD Al2O3 deposition in combination with separate capping layer deposition, and direct plasma PECVD Al2O3 with integrated capping layer deposition. A new method for rear side passivation uses a thin tunneling oxide layer with a conducting polysilicon cap layer. Instead of forming contacts to the bulk silicon the contacting is done via tunneling of electrons. This technique avoids the forming of undesired recombination centers. Optimising productivity is essential to remain cost competitive. Increasing the throughput of the equipment in order to achieve maximum output is therefore a suitable way to reduce tool related costs per cell. In order to optimise the throughput in a cell production line, both, front-end (chemical and thermal processes) and back-end (metallisation and classification) processes should have equal capacity.
Module components and types
Module conversion costs are dominated by material costs. Improvements of the module performance and of material costs are therefore mandatory to optimise module costs. The most massive material of a module is the front side glass. It mainly determines weight and light transmission properties. The thickness is also important regarding mechanical stability. It is expected that a reduction to 2 mm thickness will appear over the next years. The use of antireflective (AR) coatings has become common to improve the transmission of the front cover glass. AR-coated glass will remain the dominant front cover material for c-Si PV modules in the future, with market shares well above 90 per cent. Today, solders that contain lead are the standard interconnection technology for solar cells in module manufacturing. Due to environmental and other considerations, more PV manufacturers are striving towards lead-free alternatives. Conductive adhesives are expected to gain after 2022 above 10 per cent.
As interconnector material, copper ribbons are today the dominating material. Copper wires will gain over 40 per cent market share during the next years due to the success of half-cell technology. Overlapping interconnect technologies will also gain market share. Structured foils and non-Cu based ribbons are expected to stay at a market share of <8 per cent. The encapsulation material and the back sheet are key module components to ensure long time stability. Both are also major cost contributors in module manufacturing. Intensive development efforts have been made to optimise these components regarding performance and cost. Improving the properties of this key components is mandatory to ensure the module service lifetime. EVA will stay the most widely used encapsulation material for PV modules. Polyolefins are an upcoming alternative especially for bifacial products in glass-glass combination.
The expected area efficiency for mc-Si based products will stay below mono-Si based technologies. Current PERC p-type mono-Si modules are expected to show area efficiencies of 203 W/m² in 2020 and up to 225 W/m² in 2030. Modules with n-type cell concepts, especially with tunnel oxide passivation technologies, are expected to be ahead of p-type PERC with 208 W/m² in 2020 and with up to 230 W/m² in 10 years. In 2020, HJT modules reach 210 W/m² and are expected to outperform other c-Si module types with 238 W/m² in 2030. Modules using half-cell technology were introduced in the market in order to reduce interconnection losses and therefore improving the area efficiency and the module power. Since this technology requires an additional process step for cutting the cells as well as a modification of the stringer equipment and reduction of the stringer throughput, it has an impact on the module manufacturing process. Due to higher module efficiency, the share of half-cells will continue to grow from about 20% in 2020 to > 60 per cent in 2030.
Emerging trends
Today most of the modules are still monofacial. Bifacial cells can be used in bifacial modules as well as in conventional monofacial modules and will gain market share. It is estimated that between 50 and 60 per cent of bifacial cells will be assembled in bifacial modules and the remaining 40 -50 per cent will be used in monofacial modules. The market share for bifacial modules will increase from 10 per cent in 2020 to at least about 35 per cent in 2030. Bifacial modules will mainly be developed in power plant installations. Another trend is the development of modules for special markets and environmental conditions. It is still expected that the main market until 2030 will be for standard modules. Module for special environmental conditions like tropical climate, desert and floating PV applications will overall account about 25 per cent over the next 10 years.
The product warranty is expected to increase to 15 years and prospectively to 20 years in 2030. Performance warranty is expected to increase to 30 years from today 25 years. The degradation after the 1st year of operation will be reduced to 2 per cent. This is mainly linked to the control of light induced degradation (LID) and to the light and elevated temperature induced degradation (LeTID). Understanding the degradation mechanisms and a tight control of the degradation are mandatory to ensure the warranty. The implementation of gallium doped wafers will support this trend. In order to maintain quality (for thinner cells as well), the solar cells used for module assembly should be free of micro-cracks. The contributing companies are considering testing all the products during the manufacturing process with EL inspection as standard and with a standardised procedure that has been in preparation. The contributors consider Potential Induced Degradation (PID)-resistant cell and module concepts also as market standard. Higher level of stress testing for PID is still common. Many test labs apply test conditions beyond the minimum levels described in IEC TS 62804. Currently IEC TC82 is working on a next edition of IEC 61215 which will include testing for PID. At the same time, there has been no industry-wide accepted and applied definition of micro-cracks.
Due to the significant reduction of PV module prices over the last few years, balance of system (BOS) costs have become a crucial factor in overall system costs and thus the levelized cost of electricity (LCOE) as well. Besides warranties for the product and the product performance as well as the degradation of the modules during the operation lifetime an increase in system voltage and the trend to install more 1-axis tracking systems are important parameters to reduce LCOE. The module will stay the most expensive single cost element in a PV system. A cost reduction by about 40 per cent is expected within the next 10 years due to ongoing module price learning. One trend to be expected on system level is the trend toward an increase of system voltage from 1,000 V to 1,500 V – from 2021 onwards the market for 1,500 V systems will be >50 per cent, attaining a market share of >75 per cent after 2024 onwards. The increase in system voltage represents an important measure for lowering resistive losses and BOS costs by reducing the required diameter of the connection cables within a PV system.
Outlook
The levelized cost of electricity (LCOE) is a commonly recognized economic metric for comparing the relative costs of different renewable and non-renewable electricity generation technologies. The system cost trends assume that total direct utility-scale capital costs will decline to around $420/kW (DC) in 2030. Considering the system capital trends anticipated by the ITRPV, PV LCOE in the range of $0.02 to 0.04 are predicted by the year 2030. Due to the significant reduction of capital costs over the past decade, operations, and maintenance (O&M) expenses have become proportionally more significant factors behind the 2019 benchmark and projected LCOE of PV systems.
Going forward, ground based power plants will dominate the market accounting for about 60 per cent of all installations. The fraction of roof top systems will decrease slightly within the next decade. Floating PV systems will increase the market share to about 10 per cent. Building integrated PV is expected not to exceed 5 per cent until 2030. More of PV installations will be combined with storage systems with the share increasing from 4 per cent in 2020 to 50 per cent in 2030.
The VDMA Photovoltaic Equipment represents around 3,300 German and European companies in the mechanical engineering industry and regularly updates and publishes the ITRPV.
