oa ATHLOC: Advanced Thin Film Hybrid Low Cost PV Towards Cost Reduction of PV Through Material Optimisation and Efficient Solar Cells

The solar photovoltaic industry is dominated by crystalline silicon with a global PV market share of 90%. The global PV module production has reached about 40 GW in 2013. Competing with Si PV, thin film photovoltaic modules have reached a market share just below 10%, with dominance by two companies: First Solar for CdTe and Solar Frontier for Cu(In,Ga)(S,Se)2. Derived by the technological learning and economies of scale, solar photovoltaics industry has seen remarkable cost reductions over the past decades. One possible route to further reduce the price of the photovoltaic (PV) module and reach the grid parity is to develop an efficient PV technology based on low cost materials and processes. Thin film PV has a higher potential for cost effective production in the economy of scale than the other technologies in the market today. The competitiveness of thin film technology currently faces three significant challenges in order to achieve widespread market acceptance and adoption:

• Increasing the record efficiencies toward the theoretical limit and beyond

• Increasing the efficiency of modules (particularly, decreasing the gap between lab scale champion cells and production modules)

• Reducing direct materials and processes costs, specifically by reducing the usage of scarce materials resources

At QEERI, the recently launched grand challenge project ATHLOC-PV (Advanced Thin film Low Cost PV) aims to tackle these issues by developing in Qatar an emerging alternative PV technology. Following a roadmap towards thinner, cheaper and more efficient thin film solar cells, the main objective of ATHLOC-PV is to obtain lower cost, lighter weight and durable photovoltaic modules and to accelerate the decrease in the cost/efficiency ratio for thin film PV modules. The overall aim is to demonstrate a new-type of thin-film solar cell of conversion efficiency in the region of 20% capable of environmentally acceptable large-scale production at a manufacturing cost of below 0.5 $/watt with potential for further significant improvements in the future. To reach this objective, two alternative thin film materials are targeted in ATHLOC namely: Cu2ZnSn(S,Se)4 (CZTSSe) and Cu(In,Ga)(S,Se)2 (CIGSSe). The key advantages include favourable optical band gap (1–1.5 eV), low materials usage and consequently a lower energy-payback time, usage of flexible substrates leading to lightweight and the potential of cost-effective roll-to-roll manufacturing, high conversion efficiency potential. In addition CZTSSe has the advantage not to suffer from abundance issues compared to CIGSSe.

Table 1 compares record efficiencies from laboratory research

Thin-film PV permits a higher cost-reduction potential when up scaling to GW production volumes [2] compared to Si wafer technology. However, the limited supply of some elements (i.e. In in CIGSe) and related costs upon considerably increased production volumes present a constraint that has to be addressed. The overall aim of ATHLOC project is to reduce the use of scarce elements and still reach high efficiencies by developing low cost roll-to-roll inkjet printing processes for the fabrication of CZTSSe solar cells [3], we expect to significantly reduce the manufacturing costs of the modules. In this contribution, the objectives and the roadmap of the ATHLOC-PV project will be presented, as well as the strategy foreseen to improve the efficiency and reduce the cost of the Kesterite solar cells.

References

[1] M.A. Green, K. Emery, Y. Hishikawa, W. Warta, and E.D. Dunlop, ‘Solar cell efficiency tables (version 46)’, Prog. Photovolt: Res. Appl. 22, 701 (2014).

[2] C. Wadia, A.P. Alivisatos, and D.M. Kammen, Materials Availability Expands the Opportunity for Large-Scale Photovoltaics Deployment, Environ. Sci. Technol. 43, 2072 (2009).

[3] Xianzhong Lin, Jaison Kavalakkatt, Martha Ch. Lux-Steiner, and Ahmed Ennaoui, (2015) “Inkjet-Printed Cu2ZnSn(S,Se)4 Solar Cells, Advanced Sciences, 2, 1500028 (1–6).

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