Crystalline silicon (c-Si) remains the cornerstone of solar photovoltaic technology, celebrated for its high efficiency, durability, and widespread use in solar panels worldwide. Between 2018 and 2023, significant advancements have further elevated its performance and cost-effectiveness. The two primary types of c-Si are Monocrystalline Silicon (Mono-Si) and Polycrystalline Silicon (Poly-Si), each offering unique benefits suited to various applications. Innovations such as PERC (Passivated Emitter and Rear Cell), TOPCon (Tunnel Oxide Passivated Contact), heterojunction (HJT), and bifacial modules have pushed efficiency boundaries, making c-Si an excellent choice for Building-Integrated Photovoltaics (BIPV), where reliability and long-term performance are essential.
Monocrystalline Silicon (Mono-Si)
Mono-Si panels are crafted from a single, continuous crystal structure, identifiable by their uniform dark appearance and rounded cell edges. As of 2023, commercial Mono-Si modules have achieved efficiency rates up to 23%, with laboratory prototypes exceeding 26%. These panels are ideal for high-efficiency applications, especially in space-constrained environments like urban BIPV systems. Recent innovations—including half-cut cells, multi-busbar (MBB) technology, and shingled cell designs—have reduced electrical losses and improved performance under partial shading. Mono-Si panels also maintain superior performance in low-light conditions, maximizing energy harvest throughout various lighting scenarios.
Polycrystalline Silicon (Poly-Si)
Poly-Si panels are produced by melting multiple silicon crystals together, resulting in a cell with numerous grain boundaries. Recognizable by their bluish hue and speckled appearance, Poly-Si modules now offer efficiencies ranging from 17% to 20%, thanks to advancements in cell fabrication techniques. While slightly less efficient than Mono-Si, Poly-Si panels are more cost-effective to manufacture, offering a balanced solution where space is ample and budget considerations are significant. They are widely used in large-scale installations where overall system cost is a critical factor.
Advanced Cell Technologies
Passivated Emitter and Rear Cell (PERC)
PERC technology has become an industry standard for enhancing the efficiency of both monocrystalline and polycrystalline cells. By adding a passivation layer to the rear side of the cell, PERC reduces electron recombination and increases light absorption, boosting overall cell efficiency. Commercial PERC cells now achieve efficiencies exceeding 22%. This technology is particularly beneficial in BIPV applications where maximizing energy output from limited space is crucial.
Tunnel Oxide Passivated Contact (TOPCon) and Heterojunction Technology (HJT)
Emerging technologies like TOPCon and HJT have further pushed efficiency limits. TOPCon cells incorporate an ultra-thin oxide layer and a polysilicon passivating contact, reducing recombination losses and enhancing efficiency. HJT combines crystalline silicon with thin amorphous silicon layers, offering excellent passivation and low-temperature coefficients. These technologies are promising for next-generation high-efficiency solar cells, with commercial efficiencies approaching 24% and potential for further improvements.
Bifacial Modules
Bifacial solar modules have gained significant traction due to their ability to capture sunlight on both the front and rear surfaces, increasing energy yield by 10–30% depending on installation conditions. These modules leverage the albedo effect, utilizing reflected light from the ground or surrounding surfaces. In BIPV applications, bifacial modules are particularly advantageous for installations on façades, canopies, or rooftops with reflective materials. Their ability to generate more energy from the same footprint makes them a powerful solution for maximizing solar production in integrated building systems.
Innovations in Module Design
Advancements such as half-cut cells, multi-busbar configurations, and shingled cell layouts have enhanced the performance and reliability of c-Si modules. Half-cut cells reduce resistive losses and improve module durability. MBB technology increases the number of busbars, reducing current density and enhancing efficiency. Shingled modules overlap cells to eliminate gaps, increasing the active area and boosting module efficiency. These design improvements contribute to higher power outputs and better performance under shading or micro-crack conditions.
