Solar Panel Efficiency Calculator
Compare monocrystalline, polycrystalline, and thin-film output per panel — at any irradiance level.
| Technology | Efficiency | Output (W) | Temp coeff |
|---|---|---|---|
| Monocrystalline ★ | 21.5% | 387.0 | -0.35%/°C |
| Polycrystalline | 17% | 306.0 | -0.4%/°C |
| Thin-film | 13% | 234.0 | -0.25%/°C |
How to Use This Calculator
Select your panel type
Choose monocrystalline, polycrystalline, or thin-film. Selecting a type automatically fills in a typical efficiency for that technology — you can override it with your specific panel's rated efficiency from the manufacturer's spec sheet. The comparison table always shows all three technologies side by side at your entered panel area and irradiance.
Enter panel area
Input the physical panel area in square meters. Standard residential panels range from 1.7 m² (60-cell format) to 2.0 m² (72-cell format). Modern large-format panels can be up to 2.4 m². Check your panel's datasheet — look for "module dimensions" and multiply length × width, then convert from mm to meters.
Set efficiency and irradiance
Panel efficiency is the percentage of incoming solar energy the panel converts to electricity. This is labeled on every panel's spec sheet under "Module Efficiency" or "Efficiency (%)." The solar irradiance field lets you see how output changes at different light levels — 1,000 W/m² is the standard test condition (STC) used to rate all panels. A typical clear sunny day peaks at 850-1,000 W/m².
Read the comparison table
The table shows all three technologies at your entered area and irradiance, making it easy to compare how much extra power monocrystalline delivers vs. polycrystalline or thin-film in the same panel footprint. The temperature coefficient column shows how each technology responds to heat — a key factor in hot climates.
The Formula
The basic formula multiplies panel area by efficiency and incoming irradiance. At STC (1,000 W/m², 25°C), a 1.8 m² panel at 21.5% efficiency produces 1.8 × 0.215 × 1,000 = 387W — close to a real 400W panel rating.
The temperature coefficient matters on hot days. At 45°C (113°F), monocrystalline loses 0.35% × (45-25) = 7% output. The same heat reduces thin-film by only 5% (0.25% coefficient) — one of thin-film's advantages in hot climates like Arizona or the Middle East.
Technology Comparison
Same roof area, three technologies
This example compares how much a standard 20-panel array produces depending on technology, all at 1.8 m² per panel:
From the same 20-panel, 36 m² roof footprint, monocrystalline produces 65% more power than thin-film and 26% more than polycrystalline. For limited roof space, monocrystalline is clearly superior. Thin-film is primarily used in large commercial or utility-scale installations where land is cheap and installation simplicity (no frames, flexible mounting) matters more than efficiency.