Cost analysis of two silicon heterojunction solar cell designs Atse Louwen *† , Wilfried G.J.H.M. van Sark * , Ruud E.I. Schropp ‡§ , Wim C. Turkenburg * and Andr´ e P.C. Faaij * * Utrecht University, Copernicus Institute of Sustainable Development, PO Box 80.115, 3508TC Utrecht, the Netherlands † Telephone: +31 30 253 7618, E-mail: a.louwen@uu.nl ‡ Energy research Center of the Netherlands (ECN), Solar Energy, High Tech Campus Building 5; p-057 (WAY), 5656 AE Eindhoven § Eindhoven University of Technology (TU/e), Department of Applied Physics, Plasma & Materials Processing, PO Box 513, 5600MB Eindhoven Abstract—Research and Development of Silicon Heterojunc- tion (SHJ) solar cells has seen a marked increase since the recent expiry of core patents describing SHJ technology. This paper investigates the production costs associated with two different SHJ cell designs investigated within the FLASH programme, a Dutch research programme focusing on SHJ solar cells. We performed life cycle costing and common economic analysis to quantify the production costs (e/Wp). One of the aims of the research programme is to decrease production cost by substituting expensive materials and processing steps. We found the analyzed designs to have slightly different production costs: 0.35e/Wp for a “standard” SHJ cell, compared to 0.34e/Wp for a new SHJ cell design in which the indium-tin-oxide TCO is replaced with abundant materials. Sensitivity analysis showed the results to be especially sensitive to changes in wafer (and thus silicon) prices. Further research will be conducted for other SHJ cell designs developed in the FLASH programme. Index Terms—amorphous silicon, heterojunction, photovoltaic cells, silicon. I. I NTRODUCTION Since the expiry of core patents describing silicon het- erojunction (SHJ) technology, the steady research and de- velopment of this technology since the 1990s has seen a marked increase [1]. Aside from R&D to improve device performance, novel design structures and processing steps are being investigated, with the aim of lowering production costs. Current SHJ cell designs rely on expensive materials (silver, indium) and processing steps. In order to improve the economic performance of SHJ technology, the FLASH programme investigates several alternative SHJ cell designs. The FLASH programme (acronym for Fundamentals and Application of Silicon Heterojunction solar cells) is a Dutch research programme funded by technology foundation STW under their Perspectief programme. Perspectief programmes aim to employ fundamental technical research to apply novel technologies in society. FLASH aims to research alternatives for the current design elements and processing steps that contribute significantly to the cost of cells in terms of e/W p . The research focusses not only on replacement of expensive and high price volatility materials like indium (for the transparent conductive oxide, TCO) and silver (for metallization) but also on simplifying the production process, for instance by researching a novel emitter-TCO stack that can be deposited in one process together with deposition of the amorphous silicon passivation layer, without using precious or rare materials. This novel design and production process would eliminate the need for handling in between processes and the requirement of TCO sputtering. Naturally, cost of solar cells is one of the main parameters determining their commercial adoption. When looking at solar cells, a few design elements are generally found to contribute substantially to the overall cost of the device per W p . Silver metallization for instance offers high quality, low resistance contact formation on a variety of solar cell technologies, including SHJ. However, it is an expensive metal, with high price volatility, and supplies are not abundant. An even larger contribution to solar cell cost is the cost of the wafer used [2]. Production and purification of silicon is an energy intensive process, and wire sawing into wafers leads to loss of high quality material, together resulting in high costs per wafer. Additionally, mismatches in solar grade polysilicon production and demand have lead to significant price volatility for silicon, and thus, wafers. Other concerns in terms of the SHJ designs studied are related to the use of indium, a rare and relatively expensive material. Prices of indium are comparable with those for silver, and are volatile, as they have varied from US$ 100/kg to over US$ 1000/kg in the last ten years [3]. Currently (May 2013), prices are about 525 US$/kg [4]. Because of this high material cost, and the low abundance of the resources, indium replacement is investigated in many R&D projects. We used life cycle costing (LCC) to establish the cost (in e/W p ) of two SHJ cell designs. We aimed to identify cost- intensive design elements and processing steps, in order to highlight major cost contributors and establish potential cost reductions of the new design. The research should indicate cost-optimal design and processing steps, and quantify the benefits of design changes. Furthermore, we performed a sensitivity analysis to analyze the effect of price volatility of various materials, and cell performance, on the overall result. II. METHODS We employed life cycle costing to analyze the cost of each cell from a life-cycle point of view. In a previous study [5] we analyzed the environmental performance of different SHJ cell