We report efficiencies of >24% being consistently achieved in mass-production of passivating-contact solar cells. Furthermore, the certified efficiency of cells from our pilot line has reached 25.3% with 730 mV open-circuit voltage. An analysis of the cell performance, including simulations, shows that the cells’ rear-side is nearly ideal, while there remains potential for further optimization of the front emitter and passivation.

In recent years, we have developed the Q.ANTUM NEO solar cell, a rear-passivated double-sided contact solar cell that achieves power conversion efficiencies exceeding 25.5 %. Our streamlined and cost-efficient process leverages the proprietary Laser Enhanced Contact Optimization (LECO) technology. The LECO process has undergone extensive optimization and has been successfully implemented in both our pilot line and mass production facilities, resulting in significant improvements in solar cell efficiency. LECO facilitates a novel formation of the contact interface between the silicon surface and metallization, leading to remarkably low j0,met values (as low as 160 fA cm(- 2)). The contact resistivity of 20 mu m wide contacts on a high sheet resistance emitter is below 1 m Omega cm(2), with minimal impact on fill factor (FF) and overall cell efficiency. Rigorous reliability tests, including TC600 and DH3000, demonstrate module degradation well below 5%rel. Our champion cell conversion efficiency achieved in the pilot line using LECO technology reaches 25.6 %, accompanied by a notable open-circuit voltage exceeding 730 mV.

Within the last 3 years Q CELLS has developed its Q.ANTUM NEO technology based on a passivating contact solar cell and has transferred this technology to mass production. With a very lean and cost-effective process flow a conversion efficiency of 25.2 % has been demonstrated with this solar cell concept while average pilot line efficiency is currently at 24.7 % with a steep learning curve. This enables a high module power output of 444 W (132 half cells M6) corresponding to a module efficiency of 23.9 % on aperture area. The cell structure features a solar cell with passivating contacts on the rear side, double-sided screen-printed metal contacts, a module-optimized anti-reflective coating (ARC) and a homogeneous front-side emitter on a $n$ -type silicon substrate.

Within this work, both the performance and reliability of industrial Boron- and Gallium-doped p-type monocrystalline silicon solar cells with dielectrically passivated rear side with an average conversion efficiency of 23.6 % are investigated. Currently, in the p-type wafer market, mainly Gallium-doped material is available. Only a few studies on the so-called "Light and elevated Temperature Induced Degradation" (LeTID) of this material are available in literature. It is advertised that the well-known degradation effect caused by boron-oxygen can be avoided by using gallium as dopant. This work shows that, if not adequately suppressed, LeTID can also occur in Gallium-doped p-type Czochralski silicon passivated emitter and rear solar cells with a degradation in cell and module output power of up to 3 %(rel), which cannot be significantly suppressed in a straightforward manner by conventional processing steps to permanently deactivate the light-induced degradation defect. We demonstrate the possibility to reduce LeTID significantly on Boron- and Gallium-doped p-type monocrystalline solar cells and modules by adapting the cell process and processing sequence.

In this paper, we report significant progress in development and integration of a plasma-less atmospheric pressure dry texturing (ADE) process, performed on multicrystalline silicon (mc-Si) wafers, into high efficiency PERC solar cell architectures using industrially applied process steps. The mechanism of forming sub-micron features on monocrystalline and multicrystalline silicon wafers with commercial grade fluorine gas (F-2) is briefly presented. Low weighted surface reflection (R-w,R- min < 10%) is achieved for mc-Si substrates regardless of the wafer sawing method. Mc-Si PERC solar cells with average conversion efficiencies of 20% are fabricated in the industrial pilot line of Hanwha Q-Cells in Thalheim. A detailed characterization of ADE-textured solar cells suggest that an enhancement in conversion efficiency of up to +0.8% absolute is possible in comparison to the reference-textured solar cells by narrowing the distribution of reflectivity in the textured wafer surface.

This work addresses the latest performance of Hanwha Q CELLS industrially manufactured p-type monocrystalline silicon solar cells with dielectric-passivated rear side and the corresponding modules. Results of Q. ANTUM solar cell performance are presented, proving the feasibility of PERC-like (Passivated Emitter and Rear Cell) solar cells with solar cell conversion efficiency exceeding 22.0% in mass production while maintaining a lean and cost-effective process flow with only few more process steps compared to Al-BSF solar cells (Aluminum Back Surface Field). On module level, additional power-enhancing measures are implemented at Hanwha Q CELLS mass production sites, including the interconnection of half-sized cells by wires instead of ribbons. In total, both the high solar cell conversion efficiency and the implemented module measures enable the industrial manufacturing of 120 half-cell modules with module power classes of mostly 320 Wp and 325 Wp with the use of standard p-type Czochralski-grown silicon wafers. Indeed, modules even exceeding 330 Wp have also been fabricated.

Within this work, both the performance and reliability of industrial p-type monocrystalline solar cells with dielectrically passivated rear side and corresponding modules are investigated. Results of the mass production of Q.ANTUM solar cells at Hanwha Q CELLS on boron-doped p-type Czochralski-grown silicon (Cz-Si) substrates are presented, exceeding 21.5 % average conversion efficiency. Without power-enhancing measures such as the use of half cells, multi-wire approaches or light-capturing ribbons, essentially all currently (as of March 2017) produced Cz-Si Q.ANTUM solar modules exhibit output powers of > 300 Wp with 60 full 4-busbar cells. In terms of reliability, light-induced degradation (LID) is investigated in detail, with conditions relevant for the activation of, both, the boron-oxygen (BO) defect, and, so-called "Light and Elevated Temperature Induced Degradation" (LeTID). While the formation of the BO defect has been considered the most prominent LID mechanism in boron-doped p-type Cz-Si, LeTID has so far been discussed mainly as a potential issue for passivated emitter and rear cells (PERC) on multicrystalline silicon (mc-Si) substrates. This work shows that, if not adequately suppressed, LeTID can also occur in p-type Cz-Si PERC with a degradation in output power of up to > 6 %, which cannot be suppressed in a straightforward manner by conventional processing steps to permanently deactivate the BO defect. In contrast to conventional PERC, Hanwha Q CELLS Q.ANTUM technology is shown to reliably suppress, both, LID due to BO defect formation, and, LeTID in modules manufactured from, both, p-type mc-Si and Cz-Si substrates.

Industry-leading multi-crystalline PERC processing has been applied to kerfless wafers made directly from molten silicon using Direct Wafer™ technology, avoiding the need for ingot production and sawing of bricks into wafers, thus providing significant cost saving potential. Efficiency averaged 18,7% and a champion efficiency of 19,1% was achieved on wafers with uniform doping using only mass production tools and processes. An additional efficiency gain was obtained using non-uniform doping, with a higher dopant concentration on the backside of the wafers that we call “drift field wafers”. Simulations predict an efficiency increase of up to 0,9% in efficiency. In the first test, we demonstrated increased efficiency by 0,3% compared to uniformly doped wafers, leading to an average of 19,0%, with single cells > 19,3%. Further refinement of the wafer doping properties and co-optimization with mainstream cell process technologies will help accelerate the silicon PV learning curve and drive down costs for the prevailing multi-crystalline market.