The Remarkable Cost Reductions in Solar PV Technology: What’s Driving Them?

olar photovoltaic (PV) technology has seen remarkable cost reductions in recent years, making it an increasingly competitive option for electricity generation. Crystalline silicon is the dominant PV technology, accounting for about 90% of global PV module production. The cost of crystalline silicon solar cells has followed a steady trajectory of reduction, mainly due to improved materials use and increased equipment productivity. This trend is expected to continue in the future. One key factor affecting the cost of solar PV modules is the use of silicon material. The cost contribution from silicon material can be reduced by making the manufacturing process more efficient and by reducing the amount of silicon used in each cell. Thinner wafers and smaller kerf loss lead to lower silicon use per wafer, while kerfless wafer technology eliminates kerf loss entirely. Although kerfless solar cells have not yet achieved commercial success, new methods for producing wafers are being demonstrated in the laboratory. After wafers are produced, they are processed into solar cells using machines that convert them into electricity-generating devices. For machines that process wafers at a certain rate, shifting to larger wafers leads to higher equipment throughput. The dominant wafer size has increased several times, and 210-mm wafers are now available. Metals are applied to the front and rear of processed silicon wafers to form electrical contacts. These metallization materials usually include silver and are a major contributor to the wafer-to-cell cost. Metallization cost can be pushed down by reducing the amount of metal used or by changing to lower-cost metals. Busbarless cells use less metallization and rely more heavily on separate copper ribbons to carry electricity. The silver in conventional metallization paste may also be replaced with lower-cost metals such as copper. Historically, the cost of solar PV modules was dominated by cell cost. However, in 2020, cells constituted less than half of the module cost. Reductions to non-cell module costs are as important as cell cost reductions. Finding lower-cost module materials that do not sacrifice safety or reliability can reduce the balance-of-module materials cost. Increasing automation and increasing module size enable productivity improvements that reduce module assembly costs. According to one of the projections by US DoE report on Future of solar technology, the following figure shows module cost progress through 2020 and projected changes through approximately 2030, continued maturation of the industry and supply chains combined with incremental technology improvements are continuing to drive cost reductions in conventional technology. CdTe modules are a successful competitor to crystalline silicon, especially in the United States. CdTe technology has a path to cost reductions and performance improvements that is similar to the path for crystalline silicon. Although mainstream solar cell technology has a roadmap for further cost reduction, a shift to new solar cell types or to tandem architectures could provide a path to even lower cost. Crystalline silicon and CdTe absorbers are manufactured using expensive equipment, requiring extensive upfront investment. Reducing the capital intensity of new manufacturing facilities is essential for cost-effectively growing the PV industry in support of power-sector decarbonization. Solution-processed solar cells, such as perovskite cells, can be made from wet inks on low-cost and high-throughput equipment that is similar to a printing press. Factories based on this roll-to-roll technology could be simpler and faster to build than the facilities that produce conventional PV modules. If solution-processed cells can be made with efficiency and longevity that competes with mainstream incumbents, the low upfront cost of manufacturing equipment could enable major cost reductions. In summary, the cost of solar PV modules has followed a steady trajectory of reduction due to improved materials use and increased equipment productivity. Continued maturation of the industry and supply chains combined with incremental technology improvements are expected to drive further cost reductions in conventional technology.