In all my years in street light export, lens material is one of the details clients dig into most during technical negotiations. Some buyers focus purely on price at first, then notice that products with the exact same rated specs can have significantly different pricing depending on whether they use a glass lens or a PC (polycarbonate) lens - and the question comes right away: what's actually different between the two, and does choosing the wrong one affect the fixture's lifespan? Let's go through the real differences between glass and PC lenses properly, drawing on years of shipping experience.
Basic Property Differences Between Glass and PC Lenses
Street lights commonly use two main types of lens material: tempered glass lenses and PC (polycarbonate) engineering plastic lenses. Each has its own strengths and weaknesses in optical performance, mechanical strength, and weather resistance - neither is universally better, and the right choice depends on the specific application scenario.
1. Light Transmittance
Tempered glass lenses generally achieve an initial light transmittance of 92% or higher, and their optical performance degrades slowly over long-term use. PC lenses typically start at around 88%–90% transmittance, slightly lower than glass, though the gap isn't especially significant. For the vast majority of road lighting scenarios, this difference in transmittance has limited impact on actual road-surface illuminance.
2. Weight and Manufacturing Process
PC material has a noticeably lower density than glass, meaning it's lighter at the same dimensions and better suited to complex secondary optical distribution designs - injection molding allows for finer, more intricate lens curvature. Glass lenses, by contrast, are more limited by manufacturing constraints, with complex distribution curve shapes being relatively more difficult and costly to produce.
Comparing UV Resistance
1. Glass Lenses Have Naturally Strong UV Resistance
Glass material is inherently well-suited to withstanding UV exposure, and it rarely shows yellowing or clouding even after prolonged outdoor use. This is one of the key reasons glass lenses remain widely used in outdoor lighting applications.
2. PC Lenses Require Additional UV Treatment
PC material is relatively sensitive to UV radiation by nature. If left untreated, prolonged outdoor UV exposure can cause surface yellowing and declining light transmittance over time. This is exactly why properly run street light manufacturers typically add a UV-resistant coating or use a co-extruded UV-stabilized layer on PC lenses to slow down this aging process. We recommend explicitly requesting documentation of the UV treatment process used on any PC lens from your supplier during sourcing.
Comparing Impact Resistance
1. PC Lenses Offer Significantly Stronger Impact Resistance
PC material has excellent inherent impact toughness. At the same thickness, a PC lens's impact resistance is generally dozens of times greater than that of a glass lens. This is exactly why many projects with higher IK impact-resistance rating requirements tend to favor PC as the lens/cover material - it holds up much better against external mechanical impact like thrown rocks or deliberate damage.
2. Glass Lenses Are Relatively Fragile and More Prone to Breakage
While tempered glass lenses do have improved impact resistance compared to standard glass, they remain a brittle material compared to PC, and can crack or shatter under a strong enough impact. This is an additional safety consideration to factor in when using glass-lens fixtures in higher-risk areas - a shattered lens can also create a risk of falling glass fragments.
How to Choose the Right Lens Material Based on Project Scenario
If a project is installed in a low-risk area and prioritizes fixture weight and optical precision, a glass lens is generally a good choice. If a project involves higher-risk areas, needs to meet a higher IK impact-resistance rating, or requires strict overall fixture weight control, a UV-coated PC lens is recommended - it strikes a better balance between impact resistance and weather durability.
Conclusion
Glass lenses naturally offer better UV resistance, while PC lenses offer significantly stronger impact resistance - the right choice depends on the project's risk level and IK rating requirements. At Luxsky Lighting, both lens materials are available, and our PC lenses all undergo professional UV treatment. Feel free to reach out to our team for product recommendations.
