When shopping for solar panels, you'll encounter two main cell technologies: monocrystalline and polycrystalline. The difference comes down to how the silicon is manufactured, which affects efficiency, aesthetics, cost, and how much roof space you need.
Monocrystalline: Higher Efficiency, Higher Cost
Monocrystalline panels are made from a single silicon crystal, giving them a uniform dark appearance and higher efficiency — typically 19–23% for residential panels. Higher efficiency means more watts per square foot, so you need fewer panels to achieve the same output. Most premium panels (SunPower, REC, Panasonic) are monocrystalline. They perform slightly better in low-light conditions and high temperatures.
Polycrystalline: Lower Efficiency, Lower Cost
Polycrystalline panels are made from multiple silicon fragments melted together, giving them a bluish, speckled appearance and lower efficiency — typically 15–17%. They're cheaper per panel but require 20–30% more roof space to produce the same output as monocrystalline. As monocrystalline prices have fallen significantly, polycrystalline has become less common in new residential installations.
Cost and Space Comparison
- Monocrystalline: $0.90–1.20/W panel cost, 370–420W per panel, higher efficiency
- Polycrystalline: $0.70–0.90/W panel cost, 300–370W per panel, lower efficiency
- For a 6kW system: Mono needs ~15 panels at 400W each; Poly needs ~18–20 panels at 320W each
Which Should You Choose?
For most new installations: monocrystalline. The price gap has narrowed significantly, and the space savings matter if your roof has limited south-facing area. Polycrystalline may still make sense for large, unshaded roofs where space isn't a constraint and budget is the primary concern. Use our Solar Panel Savings Calculator to compare output scenarios.