Do unused solar panels go bad?

Yes, solar panels can experience degradation even when they are not actively in use or generating electricity. While the rate of degradation might be slower compared to panels constantly exposed to operational stresses, they are still susceptible to environmental factors that reduce their efficiency over time.

Understanding Solar Panel Degradation

Solar panel degradation refers to the gradual decrease in a panel's power output capacity over its lifespan. This process is natural for all photovoltaic (PV) modules, whether they are actively generating electricity or simply sitting unused.

Why Unused Panels Degrade

Even when not plugged into an inverter or actively powering a home, solar panels are not immune to the elements. The materials making up the panels are constantly exposed to various environmental stressors, leading to a slow but continuous decline in performance. Factors contributing to this include:

• UV Radiation Exposure: Sunlight, specifically ultraviolet (UV) radiation, can cause the degradation of the panel's encapsulation materials and backsheet. Over time, this leads to yellowing, cracking, or delamination, which can reduce light transmission and expose the solar cells to moisture.
• Temperature Extremes and Fluctuations: Cycles of heating and cooling, whether from direct sunlight or ambient temperature changes, cause materials to expand and contract. This thermal stress can lead to micro-cracks in the solar cells, solder joint fatigue, or delamination of layers within the panel.
• Humidity and Moisture Ingress: Exposure to high humidity or direct moisture can lead to corrosion of internal components, particularly the electrical contacts and busbars. Moisture can also cause delamination, where layers within the panel separate, trapping moisture and air bubbles that degrade performance.
• Physical Stress: Even in storage, panels can be subjected to minor physical stresses from handling, stacking, or ambient vibrations. Wind and dust, even on stored panels, can contribute to wear and tear.

It's important to note that while this degradation occurs, it isn't usually a significant issue for typical homeowner scenarios where panels might not always be at their peak output. However, it's certainly something to consider if you want to maximize the long-term effectiveness and efficiency of your solar energy system.

Common Degradation Rates

While specific rates vary by panel type and manufacturer, most modern solar panels are designed to degrade at a predictable and slow rate. Manufacturers typically guarantee a certain power output (e.g., 80% or 85%) after 20-25 years.

(Note: These rates primarily apply to panels in active use, but provide a general idea of how materials degrade over time, even with less stress for unused panels.)

Mitigating Degradation for Unused or Stored Panels

To minimize degradation and preserve the integrity of unused or stored solar panels, proper handling and storage are crucial.

Best Practices for Storage

• Controlled Environment: Store panels indoors in a cool, dry place away from direct sunlight. Avoid areas with extreme temperature fluctuations or high humidity.
• Protection from Physical Damage:
  • Stack panels correctly according to manufacturer guidelines, usually vertically or in small, stable stacks horizontally.
  • Use protective packaging or covers to prevent scratches, impacts, or abrasion.
  • Keep panels away from areas where they could be knocked over or damaged by other equipment.
• Cleanliness: Ensure panels are clean before storage and periodically check for dust or debris accumulation. While not generating power, a clean surface helps prevent uneven heating or material stress.
• Ventilation: Ensure adequate air circulation around stored panels to prevent moisture buildup.

By understanding that solar panels are susceptible to degradation even when not actively producing electricity and implementing proper storage strategies, you can help preserve their efficiency and lifespan for future use.