Solar Panel Types Explained: Mono, Poly, N-Type, and Thin-Film

Monocrystalline (Mono)

Monocrystalline panels use cells cut from a single crystal of silicon. The uniform crystal structure allows electrons to flow more efficiently, giving mono panels the highest efficiency of any mainstream technology.

• Efficiency: 20-22% for standard P-type mono cells. This means a standard-size panel (about 17 sq ft) produces 370-420W.
• Appearance: Black or dark blue cells with rounded corners (full-cell) or uniform black (half-cut cells). Sleeker looking than polycrystalline.
• Cost: $0.30-0.60 per watt for residential panels. Prices have dropped dramatically and mono is now comparable to poly in cost.
• Degradation: About 0.5% per year. A mono panel will still produce 87.5% of its rated power after 25 years.
• Temperature coefficient: -0.35 to -0.40% per degree C. Output drops in extreme heat but less than poly.

Monocrystalline is the standard choice for nearly every application today: rooftop solar, ground mount, RV, shed, and off-grid systems. There is rarely a reason to choose anything else unless you have a specific requirement that another technology addresses.

Polycrystalline (Poly)

Polycrystalline panels use cells made from multiple silicon crystals melted together. The grain boundaries between crystals reduce electron flow efficiency compared to mono.

• Efficiency: 15-17%. A same-size panel produces about 300-330W, roughly 20% less than mono.
• Appearance: Blue, speckled surface from the multiple crystal structures. Easily distinguished from mono by the blue color and visible crystal boundaries.
• Cost: $0.25-0.50 per watt. Slightly cheaper than mono, but the gap has narrowed to the point where the lower efficiency usually negates the price advantage.
• Degradation: About 0.5-0.7% per year. Slightly faster degradation than mono.
• Temperature coefficient: -0.40 to -0.45% per degree C. Slightly worse heat performance than mono.

Polycrystalline panels dominated the market from 2000-2015 but have been almost entirely replaced by mono. The only time poly makes sense today is if you find them at a significantly lower price per watt (e.g., used panels or clearance stock) and have plenty of mounting space.

N-Type (TOPCon and HJT)

N-type cells represent the newest generation of solar technology. Traditional mono panels use P-type (boron-doped) silicon, while N-type uses phosphorus-doped silicon. The two main N-type architectures are TOPCon and HJT (heterojunction).

• Efficiency: 22-24%. Top-tier N-type panels produce 430-470W in the same footprint as a 400W mono panel.
• Low-light performance: N-type cells perform significantly better in low-light conditions (cloudy days, early morning, late evening). This translates to more total energy production over the year.
• Less degradation: N-type cells are immune to light-induced degradation (LID) that affects P-type cells in the first year. Annual degradation is typically 0.3-0.4%, meaning 91-92% production after 25 years.
• Better temperature coefficient: -0.28 to -0.34% per degree C. N-type panels lose less output in heat, making them ideal for hot climates.
• Cost: $0.35-0.70 per watt. Premium of 10-25% over standard mono, but the higher efficiency and lower degradation often offset the cost difference over 25 years.

N-type panels are the future and are rapidly taking over production lines. If your budget allows the modest premium, N-type panels deliver more energy per square foot with a longer productive lifespan.

Thin-Film (CIGS and Amorphous Silicon)

Thin-film panels deposit a thin layer of photovoltaic material onto a substrate (glass, metal, or plastic). The main thin-film technologies are CIGS (copper indium gallium selenide) and amorphous silicon (a-Si).

• Efficiency: 11-15% for CIGS, 6-8% for amorphous silicon. Much lower than crystalline panels.
• Weight: Very lightweight. Flexible thin-film panels can weigh as little as 2-4 lbs per panel, compared to 40-50 lbs for rigid crystalline panels.
• Flexibility: Some thin-film panels can conform to curved surfaces (RV roofs, boat decks, tent canopies). This is their primary advantage.
• Cost: Variable. Flexible thin-film tends to be expensive per watt ($1-2/W) despite lower efficiency, because the niche market keeps volumes low.
• Durability: Less durable than glass-fronted crystalline panels. More susceptible to physical damage and faster degradation (0.5-1% per year).

Thin-film makes sense only when you cannot use rigid panels: curved RV roofs, backpacking, or temporary installations where weight is critical. For everything else, crystalline panels deliver far more power per dollar and per square foot.

Bifacial Panels

Bifacial panels have solar cells on both the front and back. The back side captures light reflected off the ground (albedo), boosting total output by 5-10% depending on the ground surface.

• Best surfaces: White gravel, sand, light concrete, and snow reflect the most light. Green grass reflects very little. The bonus ranges from 3% (grass) to 15% (fresh snow).
• Mounting requirement: Bifacial panels need to be elevated off the surface to allow light to reach the back. Ground-mount and carport installations benefit most. Roof-mounted panels flat against shingles get almost no bifacial benefit.
• Cost premium: 5-15% more than equivalent monofacial panels. Worth it for ground-mount installations over reflective surfaces. Not worth it for roof-mount.

Most N-type panels are bifacial by default, so you may get bifacial capability without specifically seeking it out.

Comparison Table

Which Type Should You Buy?

For the vast majority of buyers, the decision is straightforward:

• Monocrystalline for almost everyone. Best balance of efficiency, cost, and availability. This is the default choice for rooftop, ground-mount, RV, and shed installations.
• N-type if your budget allows. The 10-25% premium pays for itself over 25 years through higher production and lower degradation. Especially worthwhile in hot climates and space-constrained installations.
• Polycrystalline only if you find them very cheap. Used poly panels at $0.15-0.20/W can be a good deal for ground-mount systems where space is not limited.
• Thin-film for niche applications only. Flexible panels for curved surfaces, ultralight backpacking setups, or temporary installations.

Panel Sizing: Wattage, Voc, and Imp

Understanding a panel's electrical specifications is critical for system design. Three numbers matter most:

Wattage (Pmax)

The panel's maximum power output under standard test conditions (STC: 1000W/m2 irradiance, 25C cell temperature). Real-world output is typically 70-85% of rated wattage due to temperature, angle, shading, and wiring losses.

Open Circuit Voltage (Voc)

The maximum voltage the panel produces with no load connected. This number determines how many panels you can wire in series without exceeding your charge controller's or inverter's maximum input voltage. Exceeding the max voltage can destroy your equipment. Always check Voc at the coldest temperature your panels will experience (voltage increases in cold weather).

Maximum Power Current (Imp)

The current at maximum power point. This determines how many panels you can wire in parallel without exceeding your charge controller's maximum input current. Panels in parallel add their currents together.

For a complete guide to wiring panels in series and parallel for your specific charge controller, see our solar panel wiring guide. For sizing panels to match a portable power station, read our solar panel sizing guide.

Panels from Our Database

Browse solar panels from our database grouped by type. Visit our full solar panel catalog for filtering and detailed specs.