Why do older solar panels generate less electricity? Understand the full picture.

If electricity generation drops a few years after installing solar panels, it does not necessarily mean the panels are faulty. Learn about the changes older panels undergo and how long they can function effectively.

Solar panels continue to generate a good amount of electricity for years after installation, but their output can gradually decline over time. This does not mean the panel has suddenly failed. In reality, prolonged exposure to sunlight, heat, humidity, and weather conditions causes a gradual reduction in the panels' electricity-generating capacity. This process is known as "Solar Panel Degradation."

Typically, solar panel performance may decline by about 0.3% to 1% annually, with the industry average degradation rate cited at around 0.5% per year. Let’s explore why older solar panels generate less electricity.

Why do older solar panels generate less electricity?

Solar panels are constantly exposed to sunlight and UV rays. Additionally, heat and changing weather conditions affect the cells and their internal connections. The cycle of panels heating up during the day and cooling down at night causes repeated expansion and contraction. Over time, this can lead to the formation of micro-cracks and weaken internal connections. Consequently, the pathways for electrons are restricted, impacting electricity generation.

Initial power output can also drop due to this factor.

Older P-type solar panels may experience "Light-Induced Degradation" (LID). Following initial exposure to intense sunlight, a process occurring within the silicon cells can cause an initial drop in efficiency of approximately 1% to 3%. This is an initial decline, after which performance stabilizes. This issue has been significantly reduced in modern N-type panels.

PID and weather conditions also have an impact.

"Potential-Induced Degradation" (PID) can occur due to factors such as high voltage, heat, and humidity. This affects the solar cell's ability to generate electricity. Additionally, prolonged exposure to moisture, rain, UV rays, and hot weather can affect the internal components of the panels.

Dirt also reduces power generation

The accumulation of dust, bird droppings, pollution, and leaves on the panel surface reduces the amount of sunlight reaching the cells. In dusty areas, a lack of regular cleaning can lead to a 10% to 20% drop in power generation.

How long do solar panels last?

The operational lifespan of solar panels is generally considered to be between 25 and 30 years. Panels do not necessarily stop working after 25 years; rather, their power output may decrease. Many panels continue to generate electricity even after this period. High-quality panels, proper installation, regular cleaning, and periodic inspections can help minimize the decline in efficiency.