📉 Aging Gracefully: What Happens to Solar Panel Output Over Time

Solar panels do not suddenly fail; they simply produce less electricity each year. This predictable decrease is known as degradation.

1. The Causes of Degradation

Degradation is a result of several internal and external factors.

• ✅ **Light-Induced Degradation (LID):** A small, one-time efficiency loss (1-3%) that occurs within the first few months of exposure to sunlight. Modern manufacturing techniques have minimized this effect.
• ✅ **Thermal Cycling:** Repeated heating and cooling cycles over decades cause the materials, especially the encapsulation and soldering joints, to stress and crack slightly.
• **Potential-Induced Degradation (PID):** High voltage potential between the solar cell and the grounded frame can reduce performance; high-quality panels are now certified PID-resistant.

2. The Performance Warranty Guarantee

The 25-year performance warranty protects against excessive power loss.

• **Year 1:** Warranty guarantees at least 97-98% of the initial rated power.
• **Annual Decline:** The system is guaranteed not to lose more than 0.5% to 0.7% of its output per year thereafter.
• **Year 25:** Warranty guarantees the panel will still produce at least 80% to 87% of its original rated power.

The Bottom Line

A quality solar system installed today is expected to still be producing a significant amount of electricity 30 to 40 years from now. The degradation rate is factored into your initial energy savings calculations. 💡