Does Polycarbonate Greenhouse Turn Yellow in the Sun?

Polycarbonate is one of the most popular materials for greenhouse construction due to its light transmission, impact resistance, and thermal insulation. However, many greenhouse owners and buyers worry about one crucial question:

Does a polycarbonate greenhouse turn yellow when exposed to sunlight over time?

In this article, we explore the science behind polycarbonate yellowing, what causes it, how modern UV protection technology helps prevent it, and how you can choose the best panels to ensure long-term durability for your greenhouse investment.

1. Why Do People Worry About Yellowing Polycarbonate?

Greenhouse users care deeply about clarity and longevity. If your polycarbonate panels become yellow or hazy, it affects:

• Light Transmission: Reduced sunlight for your plants.

• Aesthetics: A yellow greenhouse looks old and poorly maintained.

• Functionality: Hazy panels can reduce crop productivity and energy efficiency.

This concern is valid—early generations of polycarbonate panels did yellow over time, especially under intense UV radiation. But things have changed.

2. What Causes Polycarbonate Panels to Turn Yellow?

The yellowing of polycarbonate is typically the result of:

• UV Radiation: Prolonged exposure breaks down polymer chains in the material.

• Oxidation: UV rays accelerate chemical reactions that create discoloration.

• Poor-Quality Manufacturing: Panels lacking proper UV coating degrade faster.

In unprotected panels, yellowing can begin in just 1-2 years, especially in hot, sunny climates like Southeast Asia, the Middle East, or Australia.

3. UV-Coated Polycarbonate Panels: The Game Changer

Modern polycarbonate sheets come with UV-resistant coatings, which significantly extend their lifespan. There are typically two types:

• Single-sided UV coating: Protects the outer surface.

• Double-sided UV coating: Protects both sides (ideal for greenhouses).

These coatings block 99.9% of harmful UV radiation, preventing yellowing and preserving clarity for 10+ years under normal outdoor conditions.

Tip: Always confirm if your greenhouse panels have co-extruded UV protection. Cheaper panels without this feature will yellow quickly.

4. How to Identify High-Quality, UV-Protected Polycarbonate Sheets

When selecting polycarbonate for your greenhouse, ask your supplier:

• Does it have a UV coating? Is it single or double-sided?

• What’s the warranty against yellowing?

• What’s the light transmittance rate after 5 or 10 years?

• Are there lab test reports (e.g., QUV accelerated weathering tests)?

Premium-grade polycarbonate panels will retain over 80% light transmittance even after 10 years of exposure.

5. Real-World Case: Greenhouses in High-UV Regions

In regions like the Middle East, where summer temperatures exceed 45°C and sunlight is intense year-round, UV-resistant polycarbonate panels are a must.

Many commercial growers in Saudi Arabia and the UAE now use 6mm twin-wall polycarbonate with double UV coating, reporting:

• No significant yellowing after 7+ years.

• Consistent yields thanks to stable light conditions.

• Lower maintenance costs compared to PVC or film greenhouses.

6. Maintenance Tips to Prevent Yellowing and Maximize Longevity

Even UV-protected panels benefit from regular maintenance:

• Clean panels every 3-6 months with water and mild soap to prevent dust buildup.

• Avoid harsh chemicals that may damage the UV coating.

• Install panels with the UV-coated side facing the sun (many have printed stickers indicating the UV side).

7. When Should You Replace Yellowed Panels?

If you notice:

• Light transmission dropping significantly,

• Visual yellowing or hazing,

• Brittle surfaces or cracking,

…it may be time to replace your panels. Usually, well-maintained, UV-protected polycarbonate lasts 10–15 years before needing replacement.

8. Final Answer: Do Polycarbonate Greenhouses Turn Yellow in the Sun?

Yes, they can—but only if the polycarbonate is uncoated or low quality.

With proper UV protection and regular care, high-grade polycarbonate greenhouse panels will stay clear and functional for over a decade.

Conclusion: What Should You Look For as a Buyer?

If you’re investing in a polycarbonate greenhouse, here’s a quick checklist:

✅ Double-sided UV-coated polycarbonate
✅ Manufacturer warranty (at least 10 years)
✅ Strong light transmission (80%+)
✅ Real-world usage cases or test reports

Choosing the right panels means you won’t need to worry about yellowing—and your crops will thank you.

Interested in Durable Greenhouse Panels?

We manufacture commercial-grade polycarbonate greenhouses with premium UV protection, suitable for all climates. Contact us for free consultation and samples.