Polycrystalline silicon solar cells have become a dominant technology in the photovoltaic industry due to their balance of efficiency, cost-effectiveness, and scalability. The fabrication process begins with the production of multicrystalline silicon ingots through directional solidification in a casting furnace. High-purity metallurgical-grade silicon is melted in a quartz crucible coated with silicon nitride to prevent sticking. The molten silicon is then cooled under controlled conditions to form a large block with multiple crystal grains. Unlike monocrystalline silicon grown via the Czochralski method, this casting process is simpler and consumes less energy, resulting in lower production costs.

The structure of polycrystalline silicon solar cells consists of grains with varying crystallographic orientations separated by grain boundaries. These boundaries introduce defects that act as recombination centers for charge carriers, reducing the overall efficiency of the cell. However, advancements in material processing have mitigated these effects. Hydrogen passivation, for instance, is widely used to neutralize dangling bonds at grain boundaries. During the cell fabrication process, hydrogen atoms diffuse into the silicon bulk, typically from silicon nitride anti-reflective coatings deposited via plasma-enhanced chemical vapor deposition (PECVD). This treatment significantly improves minority carrier lifetime and cell efficiency.

The performance of polycrystalline silicon solar cells is generally lower than that of monocrystalline cells due to higher defect densities. Typical commercial polycrystalline cells achieve efficiencies between 17% and 19%, whereas monocrystalline cells reach 20% or higher. However, the cost advantage of polycrystalline silicon is substantial. The casting process yields higher throughput, and the material waste is minimized since square-shaped wafers can be cut directly from the ingot without the circular losses associated with monocrystalline wafers. Additionally, the lower energy consumption during ingot production translates to a shorter energy payback time, making polycrystalline cells more sustainable in large-scale deployments.

Anti-reflective coatings play a critical role in enhancing light absorption in polycrystalline solar cells. Silicon nitride is the most common coating material due to its excellent passivation properties and optimal refractive index, which reduces surface reflection. Advanced texturing techniques, such as acidic or alkaline etching, create a rough surface that further minimizes reflectance. These improvements have narrowed the efficiency gap between polycrystalline and monocrystalline cells over the years.

Industrial adoption of polycrystalline silicon solar cells has been widespread, particularly in utility-scale solar farms and rooftop installations. Manufacturers favor the technology for its lower capital expenditure and faster production cycles. While monocrystalline cells now dominate the high-efficiency segment, polycrystalline cells remain competitive in markets where cost per watt is a primary consideration.

Recent advancements in casting technology have improved grain size and reduced impurity concentrations in multicrystalline silicon. Techniques such as seed-assisted growth and optimized cooling profiles help produce larger, more uniform grains, which enhance charge carrier mobility. Additionally, gettering processes remove metallic impurities during wafer processing, further boosting cell performance.

Despite the rise of newer technologies like PERC and heterojunction cells, polycrystalline silicon solar cells continue to hold a significant share of the global photovoltaic market. Their straightforward manufacturing process, combined with continuous incremental improvements, ensures their relevance in both established and emerging solar markets. Future developments may focus on further reducing grain boundary losses and integrating cost-effective light-trapping schemes to push efficiencies closer to those of monocrystalline counterparts.

In summary, polycrystalline silicon solar cells offer a compelling combination of affordability and performance. The casting process enables high-volume production with lower energy input, while advancements in passivation and anti-reflective coatings have steadily improved efficiency. While they may not match the peak performance of monocrystalline cells, their cost advantages ensure continued industrial adoption, particularly in large-scale solar installations where economic factors outweigh marginal efficiency gains.