Monocrystalline vs polycrystalline solar panels: which to pick in 2026

In 2010 polycrystalline outsold monocrystalline. Today mono owns 95% of the market. Why? And more importantly: is there any case left for poly?

Physical difference

Mono is made from a single silicon crystal (Czochralski ingot) sliced into wafers. Poly melts recycled silicon in a mold, forming many small crystals. Visually: mono is uniformly bluish-black; poly looks blue with a leopard-skin pattern.

Real-world efficiency

Modern mono (PERC, TOPCon): 20-23%. Poly: 16-18%. The gap matters when you have limited roof: mono covers your demand in fewer sqft. On a big roof the difference washes out because space stops being the bottleneck.

Price per watt

In 2026 both run $0.27-0.50/W for Tier 1 brands. The premium for mono is now marginal because mono wafer production is fully automated. 10 years ago mono cost 40% more; today 5-10%.

Heat behavior

Both lose efficiency with temperature. Mono: -0.3 to -0.4%/°C. Poly: -0.4 to -0.5%/°C. In hot climates mono wins clearly. In temperate climates the gap is irrelevant.

Lifespan and degradation

Tier 1 mono: 0.4-0.5%/year degradation, 85% rated power guaranteed at 25 years. Poly: 0.7%/year, 80% at 25. Difference: at year 25 mono delivers ~5% more relative to nameplate than poly.

When does poly still make sense?

Only two cases: 1) You find clearance stock at deep discount and have plenty of space; 2) You live in cold cloudy climates where the efficiency gap shrinks. Otherwise: mono PERC or TOPCon, no contest.

Unsure of which brand? Read Tier 1 vs cheap brands and whether bifacial panels are worth it.