Cell Processing

Improving PERC cells requires rather different strategies than standard cells have required, demanding concrete improvements in materials, manufacturing procedures and fabrication tools.

Improving the texturing approach for diamond wire-sawn (DWS) multicrystalline silicon (mc-Si) wafers is one of the key steps to decrease its efficiency gap with monocrystalline silicon-based solar cells. In this regard, black silicon texturing has increasingly caught attention of both academia and industries as a potential approach towards mass production of high-efficiency mc-Si solar cells. In this paper, the challenges of implementing such a texture, with unique feature sizes, in mass production are discussed in detail, and the latest results are reviewed. Finally, results of the first trials at high volume manufacturer applying an alternative plasma-less dry-chemical etching (ADE) method are presented.

State-of-the-art black-silicon texturing technology has been successfully implemented in all of the 4.5GW multi-Si cell production lines at Canadian Solar (CSI). With a combination of black-silicon texturing and diamondwire-sawn wafers, it has been possible to increase cell efficiency and wattage, while significantly reducing the cost. To further improve CSI’s multi-Si product performance and cost, multi-Si passivated emitter rear contact (multi-PERC) technology has been developed to achieve a mass production cell efficiency of more than 20% on average, and a module power exceeding 300W. By the end of 2017, a production capacity of over 1GW had been established, and CSI’s majority multi-Si cell capacity will be upgraded to PERC in 2018. This paper will introduce the solutions to realizing light-induced degradation (LID)-controlled multi-PERC cells and modules, as well as offering a discussion of the degradation performance. In addition, the technology evolution of CSI’s high-efficiency multi-Si products and a roadmap for 22%-efficiency multi-Si cells are presented.

TOPCon is regarded as a possible follow-up technology to the passivated emitter and rear cell (PERC) concept. This paper presents the latest results for high-efficiency solar cells, and the progress made on migrating layer deposition to high-throughput tools, which are already in use in industry. Possible metallization approaches, and three different industrially relevant solar cell structures featuring TOPCon, are also discussed.

We present an n-type bifacial IBC solar cell that uses a simple process comparable to our industrially proven n-type cell process for conventional H-grid front- and rear-contacted n-PERT cells. The process is based on tube diffusion and a simultaneous single-step screen-print of the contacts to both polarities, and has been demonstrated on an industrial line at pilot scale.

Relatively few experimental and academic studies about bifacial p-type PERC cells have been published to date. This paper looks at the experimental findings from JinkoSolar’s large area, industry-grade bifacial monocrystalline silicon PERC (biPERC) cells.

Because of its symmetrical a-Si/c-Si/a-Si structure, silicon heterojunction (SHJ) cell technology offers the possibility to use much thinner wafers, and thus to reduce material and production cost. In order to evaluate the industrial feasibility of these thinner heterojunction cells, wafers from the standard thickness of 160μm down to 40μm were processed on the heterojunction pilot line at CEA-INES.

Optical confinement is essential in order to increase the amount of photogeneration in a crystalline silicon (c-Si) solar cell. Fraunhofer examines the compatible options for wafers created using diamond wire sawing.

The deployment of renewable energy, especially solar, is becoming ever more popular. It is estimated that with every 1% increase in PV cell efficiency, electricity costs would decrease by 7%; therefore, improving solar cell efficiency is very important for reducing the average electricity-generating cost of solar and driving it towards grid parity.

Since its first publication in 2015, the PERC+ cell concept, which is based on a passivated emitter and rear cell (PERC) design with a screen-printed Al finger grid on the rear, has been rapidly adopted by several solar cell manufacturers worldwide.