Solar Panel Degradation in Australia

How fast do solar panels degrade in Australia?

Solar panels degrade at an average rate of 0.5% to 0.8% per year. After 10 years, a high-quality panel should still produce at least 90% of its original rated capacity. If your system's output drops significantly faster than this, you may have a warranty claim.

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Nothing lasts forever, especially electronics bolted to a roof under the punishing Australian sun. Solar panels degrade. It is a physical certainty.

The problem is that most homeowners confuse normal degradation with systemic failure. They see a slight drop in output over a few years and assume they need to replace the entire array. Installers are often happy to oblige.

Here is the truth about panel degradation, what causes it, and how to tell the difference between normal wear and a defective product.

The Physics of Degradation

Solar cells are made of silicon. When photons from sunlight strike the silicon, they knock electrons loose, creating an electrical current. Over time, the physical structure of the silicon cell breaks down.

This happens for three main reasons:

1. Light-Induced Degradation (LID): This happens in the first few days of exposure to sunlight. The oxygen in the silicon reacts with the boron used to dope the cell, causing a rapid initial drop in efficiency of about 1% to 3%. This is completely normal and is factored into the panel's rating.
2. Thermal Cycling: Australian roofs get incredibly hot during the day and cold at night. This constant expansion and contraction stresses the solder joints and the protective materials within the panel.
3. UV Exposure: The backsheet and the encapsulant (the glue holding the panel together) slowly break down under intense UV light. If these materials fail, moisture enters the panel, leading to rapid corrosion.

The Warranty Standard

When you buy a tier-one solar panel, it comes with a performance warranty. This is a legal guarantee from the manufacturer that the panel will not degrade faster than a specified rate.

The industry standard is a 25-year performance warranty. It typically guarantees that the panel will produce at least 97% of its rated power after the first year, and then degrade by no more than 0.7% each year after that.

By year 25, the manufacturer guarantees the panel will still produce at least 80% of its original power.

Normal vs. Abnormal Degradation

How do you know if your drop in output is normal?

If your 5kW system produced an average of 20kWh a day when it was new, and five years later it produces 19kWh a day, that is normal degradation.

If that same 5kW system drops to 12kWh a day after five years, you have a problem. That is not normal degradation. That is a fault.

Abnormal degradation is usually caused by physical damage. Look for:

• Micro-cracks: Invisible to the naked eye, these occur when panels are mishandled during installation or hit by severe hail.
• Snail Trails: Dark, discoloured lines appearing on the silver grid lines of the cell. This indicates moisture ingress and chemical breakdown.
• PID (Potential Induced Degradation): A complex electrical issue where voltage leaks from the cells to the panel frame, drastically reducing output.

When to claim warranty

If you suspect abnormal degradation, you cannot simply call the manufacturer and demand new panels. You need proof.

You must hire an independent solar technician to perform a performance test and a physical inspection. If they confirm the panels are degrading faster than the warranty allows, they will provide a report. You then submit this report to the manufacturer (or the company that installed the system) to initiate a warranty claim.

Do not replace panels simply because they are a few years old. Let them degrade normally. They are still making you money.