Maintaining the cost reduction trajectory for solar PV

Why is this gap important?

While dramatic scale effects have been achieved in solar PV, R&D efforts focused on efficiency and other fundamental improvements in solar PV technology need to continue to keep on pace with the SDS. Mainstream technology at present is dominated by crystalline silicon. Within it, screen-printed Al-back surface field cells (Al-BSF) holds around three quarters of the market, with the remaining quarter dominated by Passivated Emitter Rear Cell technology (PERC).  Strong global demand for higher-efficiency modules is driving a shift towards PERC and the next generation of technologies, like n-type HJT and IBC.

Technology solutions

  • P-type cells, built upon a positively charged silicon base (to which Al-BSF and PERC belong) are the traditional PV development pathway that has dominated the industry – to some degree because in the early days of development dominated by space applications, p-type cells proved better suited to withstand radiation.
  • Crystalline silicon p-type PERC technology is poised to reach 24% efficiency, a key milestone, and efforts need to continue to maximise its potential and complete the market shift. Among the barriers that remain, improved cleaning, passivated contacts, interconnection, embedding, and new metallisation pastes particularly are needed.
  • In n-type cells, the basis of the cell is inverted to yield a number of advantages: n‑type cells are not subject to Light-Induced Degradation (LID; degradation over time from exposure to light), are less prone to defects and impurities in the silicon, and generally have greater power output over time. A variety of designs are in development. Overall, there a pressing need to identify a means to get n‑type technologies to the market (TRL 7).
  • Passivated contacts promise further improvements, but production throughput, homogeneity, yields and metal paste-contacting remain challenging. TOPCon technologies (an umbrella term for passivated contacts) hold especial promise as a follow-up to PERC technology. In standard contacts, which consist of pure metallisation on the wafer, losses are high. Passivated contacts reduce losses and have higher efficiencies than almost any other design structure, but they are complex to manufacture (requiring additional equipment and steps, a more expensive wafer, etc.), which is a key barrier in a traditionally conservative PV industry. Fundamentally, the metallisation paste is proving a key area of focus for scaling up.

Advancing n-type technologies Readiness level:

TOPCon technologies Readiness level:

Colored bars represent the Technology Readiness Level (TRL) of each technology. Learn more about TRLs

What are the leading initiatives?

  • R&D is relatively well funded, but commercialising novel n‑type technologies and improving PERC beyond 24% are challenging. While well followed, there is a need to develop commercial designs and products.
  • China’s Top Runner Program has chosen some next-generation PV technologies for deployment, including TOPCon technology.
  • Longi Solar/CPVT-verified 24.6% PERC cell and PV Celltech technologies are being developed.
  • OECD statistics shows the most innovation within all generation technologies coming from more efficient solar PV