SITA – Stable Inorganic TAndem solar cells
The project focuses on the next generation of stable inorganic tandem solar modules with superior device efficiency. SITA aims to explore an innovative concept for tandem solar cells with a two-terminal approach based on two technologies with a strong competence base in Europe: Silicon Heterojunction (SHJ) and high bandgap heterojunction of copper indium gallium selenide (Cu(In,Ga)(Se,S)2, CIGS) .
The new tandem concept – which requires no additional cables or electronics – is made possible by recent developments in broadband CIGS devices that lead to high efficiency (>18%). SITA will demonstrate the durability of the new modules under realistic outdoor conditions and deliver the next generation of stable inorganic tandem solar modules with superior device efficiency (>30%).
SITA’s technology will increase the efficiency of SHJ modules by a factor of 1.5, with a marginal increase in the use of the most expensive raw materials. This in turn results in a significant reduction in system costs per installed capacity and a corresponding decrease in the levelized cost of electricity (LCOE).
Tandem junction efficiencies have recently approached or even exceeded the Shockley-Queisser limit for prototype devices. SITA will address remaining limitations in terms of stability, scale, production costs and environmental impact.
Imec will contribute its expertise in Si module fabrication, energy yield modeling and passivation technologies within the SITA project. Imec will produce Si mini modules for the tandem cells using shingling and multiwire technology. For the upper CIGS module, dielectric passivation layers deposited with ALD are investigated. The energy yield model will predict the performance of the tandem module and compare it with outdoor measurements. It will provide a feedback loop and ‘what-if’ scenarios for SITA’s tandem technology.
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