Solar Panel Degradation: What to Expect Over 25 Years in Ireland

Modern solar panels are built to last, but like any technology exposed to weather and temperature changes, they slowly decline in performance over time. This natural process is known as solar panel degradation, and it is something every Irish homeowner should understand before investing in a system.

The key point is that degradation does not make your system unreliable. It is predictable, gradual, and already factored into your long term yield estimates. In Ireland, where solar panels operate in a mild climate compared to southern Europe, degradation rates are often lower than the global average.

In this guide, you will learn how solar degradation works, what percentage loss to expect over 25 years, and the steps you can take to maintain strong long term performance.

What Is Solar Panel Degradation?

Solar panel degradation is the gradual reduction in the amount of electricity a panel can produce compared to when it was brand new. Most panels lose only a small amount of output each year due to:

• UV exposure
• Temperature cycles
• Material fatigue
• Microscopic cell cracks
• Humidity and moisture over time

All reputable manufacturers provide power output warranties that clearly state the minimum performance you can expect after 25 years.

Typical Degradation Rates for Ireland

The global average solar degradation rate is roughly 0.5 percent per year. In Ireland, the rate is often slightly lower because:

• Panels operate in cooler temperatures
• Extreme heat stress is rare
• Irish systems are designed with ventilation in mind

Most Tier 1 solar panels in the Irish market guarantee around 80 to 85 percent performance after 25 years. That means your system may lose only 15 to 20 percent of its original output over its lifetime.

If you are comparing system options or planning your installation, our guide to solar panel efficiency in Ireland can help you choose modules that hold their performance over time. You can read it here:
Solar Panel Efficiency in Ireland: What Percentage Should You Expect?

What Causes Faster Degradation?

Although Irish conditions are gentle on panels, certain factors can speed up degradation:

1. Poor installation

Incorrect mounting, insufficient ventilation, or tightly packed cables can increase heat buildup and stress.

2. Shading issues

Regular shading from trees or chimneys can create hot spots that weaken cells over time. Learn more about how shading affects performance here: How Shading Affects Your Solar Output

3. Low quality panels

Cheaper panels often use weaker materials, thinner frames, or less advanced cell technologies, resulting in quicker performance loss.

4. Weather damage

Salt air near the coast, persistent moisture, or storm debris can impact panels if the mounting system is not rated correctly.

How to Reduce Degradation and Maintain Strong Output

You cannot stop degradation completely, but you can minimise it with smart choices and good maintenance. Here are the most effective steps.

Choose high quality, low degradation panels

Panels that use half cut cells, N Type technology, and anti PID coatings naturally age more slowly.

Install optimisers or microinverters where needed

These help manage shading, limit stress on individual panels, and improve long term reliability. If you are deciding between setups, our guide on inverter types can help:
Microinverters vs String Inverters: Which Is Better for Irish Home

Ensure proper mounting and ventilation

Panels perform best when they stay cool. A well designed mounting system helps prevent heat buildup.

Book periodic maintenance checks

A quick inspection every few years ensures there are no loose connections, debris buildup, or waterproofing issues.

What Performance Can You Expect After 25 Years?

With modern panel technology and proper installation, most Irish homes can expect:

• Less than 1 percent output loss per year
• At least 80 percent performance after 25 years
• Stronger returns with high quality panel brands

Your system will not suddenly fall off a cliff after the 25 year mark. Many panels continue generating stable power well beyond 30 years, often with only gradual additional decline.

Is Degradation a Reason to Delay Going Solar?

In short, no. Solar panel degradation is predictable, manageable, and already built into your long term savings calculations.

The sooner you install your system, the sooner you start reducing your energy bills and producing clean electricity. If you want to understand how solar performance affects home appliances, including EV charging, you can read our guide here:
Can You Use Solar to Power Your EV at Home

Final Thoughts

Solar panels naturally lose a small amount of performance over time, but high quality modules installed by a professional team will continue delivering strong output for decades. When you combine this with Irish solar incentives and rising energy prices, the long term value remains excellent.

If you want a detailed assessment of your roof, shading profile, or long term yield, our team can help you design the best system for your home.