___ cells are made of a single crystal and offer a higher efficiency but come at a higher price.

• A. Polycrystalline
• B. Monofacial
• C. Bifacial
• D. Monocrystalline

Answer: (D)

Monocrystalline cells are made from a single crystal silicon ingot. That uniform crystal structure means there are fewer grain boundaries to impede the flow of charge, so electrons and holes move more efficiently. The result is higher electrical efficiency, which allows more power from a given area. The trade-off is cost, because growing and processing a pure single crystal and producing wafers with minimal waste requires more expensive equipment and tighter manufacturing controls. Polycrystalline cells, by contrast, use many crystals, have more grain boundaries that can reduce efficiency but are cheaper to produce. Bifacial and monofacial describe how the panel collects light (both sides vs. one side) and don’t define crystal structure.