Project Description

Application relevant validation of c-Si based tandem solar cell processes with 30 % efficiency target

In the SiTaSol project we develop solutions for III-V/c-Si tandem solar cells with conversion efficiencies exceeding 30 %. Such a tandem solar cell will result in huge savings of land area and material consumption for photovoltaic electricity generation and offers clear advantages compared to today’s products. The tandem cells which are developed in SiTaSol will have only one front and back contact and therefore serve as a drop-in-replacement for today’s Si standard module fabrication.

 GaAsP/Si tandem solar cell on silicon realised by direct growth (Concept A, left) and Ga(In)AsP/Si tandem solar cell on silicon realised by III-V layer transfer (Concept B, right).

But one of the challenges of the technology is to achieve competitive costs. We have calculated that the additional costs for the 2-5 μm Ga(In)AsP epitaxy and  processing must remain below 1 €/wafer (156x156 mm2) to enable module costs <0.5 €/Watt-peak. It is the intention of the SiTaSol project to evaluate processes which can meet this challenging cost target and to proof that such a solar cell can be produced in large scale.

Key priorities are focused on the development of a new growth reactor with efficient use of the precursor gases, enhanced waste treatment, recycling of metals and low cost preparation of the silicon substrate. High performance devices will be demonstrated in an industrial relevant environment.

The project SiTaSol approaches these challenges with a strong industrial perspective and brings together some of the most well-known European partners in the field of Si PV and III-V compound semiconductors. Furthermore SiTaSol will support the competitiveness of the European industry by providing innovative solutions for lowering manufacturing costs of III-V materials which are essential in today’s electronic products including laptops, photonic sensors and light emitting diodes.