Technological and economic conditions for mass production beyond the roadmap of mainstream silicon PV
10:05 - 10:35
Auditorium between Building 4 and 5
Crystalline silicon solar cells have been the mainstream in global production due to an international community of researchers, dedicated development efforts of standardized production, and huge factories in China and South-East Asia. More than 100 Gigawatts are produced per year (which is equivalent to the power capacity of 100 typical nuclear power stations), and standardization of design, process and materials across the entire supply chain has lowered the fabrication cost greatly: roughly speaking, a standard Si wafer costs less than 70 cents of US$, fabricating a solar cell near 35 cents, module assembly a further 70 cents per cell. For all these reasons, it is hard for alternative cell concepts or materials to enter the mainstream. To gain a big market share, the alternatives must be stable over many years, must not consume scarce materials or lots of energy, and must be cheap and cheaper.
Yet, the mainstream mono-crystalline PERC silicon technology will probably reach its practical efficiency limits near 24% cell efficiency in about 8 years (assuming no major disruptions or breakthroughs), with projected fabrication cost down to half. The presenter believes that this will be a great opportunity for other materials and technologies to come into mainstream via hetero emitters, passivated contacts, and so on. Entering the market with an alternative material or technology is only possible starting from a small scale, hence combining these other materials with silicon wafers may then be helpful to enter mainstream, which may eventually lead to tandem cells or cells without silicon.
However, a new cell concept with 30% efficiency must cost only about 50% more than silicon mainstream costs with 20% efficiency. This economical pressure will sort out many alternative cell concepts, alternative materials, and alternative fabrication processes. The presenter therefore calls for a 10-year strategy that is very carefully chosen, so this great opportunity for other materials and technologies to come into mainstream can be realized.