Low cost multicrystalline bifacial PERC solar cells – Fabrication and thermal improvement

•Low cost and high efficiency multicrystalline silicon solar cells can be achieved.•Bifacial power generation capacity achieved by simple process.•A rapid thermal annealing used to improve cell performance furtherly. It is important to find a more cost-effective way of putting multicrystalline silicon as the mainstream silicon materials for industrial silicon solar cell fabrications. This paper presents a low-cost, bifacial multicrystalline PERC (passivated-emitter and rear cell) cells approach. Instead of the traditional PERC cells with full-area aluminum back surface field, cells rear-side is treated with aluminum grid pattern and firing-through aluminum paste. Thus, the bifacial power generation is obtained, and the laser ablation step is avoid and the consumption of aluminum paste is reduced. Rear surface passivation and metal contact are optimized via enhancing the corrosiveness of aluminum paste, matching the passivation film and improving the co-firing process. LID (light induced degradation) phenomenon of this kind of cell is controlled within a reasonable range by both light injection annealing and electric injection annealing. In addition, an anneal at 385 °C can further increase the cell efficiency by 0.2% absolute. The average batch efficiency of the front-side can reach 19.63%. The champion cell efficiency is 19.86% on the front and 13.65% on the rear.