Solar Panel Efficiency Explained

Understanding how solar panel efficiency affects your system size, cost, and energy production.

Key Specifications

Top Residential Efficiency22.8% (SunPower Maxeon)
Average Panel Efficiency19-21%
Theoretical Maximum~33% (Shockley-Queisser)
Annual Degradation0.25-0.5%
Real-World vs Lab2-5% lower in field
Temperature ImpactLoses 0.3-0.5% per °C above 25°C

Pros

  • +Higher efficiency = fewer panels needed
  • +Better use of limited roof space
  • +Higher production per dollar in constrained spaces
  • +Efficiency improving ~0.5% per year

Cons

  • -Highest efficiency panels cost more
  • -Diminishing returns above 20%
  • -Real-world efficiency lower than rated
  • -Efficiency drops in extreme heat

Best For

Anyone comparing solar panels who wants to understand the efficiency tradeoffs between cost and performance.

Average Cost

Varies by panel type

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