Rectangular Hollow Sunlight Sheet

Updated: 2026-09-16

Overview

Rectangular Hollow Sunlight Sheets are engineered polycarbonate panels with a multi-chambered hollow structure, optimized for diffusing natural light while minimizing heat transfer. Developed as an alternative to glass, these sheets are 200 times more impact-resistant and 50% lighter, making them ideal for large-span installations. The rectangular cell design enhances structural rigidity, allowing spans up to 2.1 meters without secondary support. First adopted in European industrial buildings during the 1990s, this product has become a global standard for daylighting systems. Modern versions incorporate nano-scale UV inhibitors that block 99% of harmful radiation while maintaining 80–88% light transmission, outperforming traditional fiberglass panels.

Structure and Working Principle

The sheet's performance derives from its extruded multi-wall profile, typically featuring 2–4 rectangular air chambers running parallel to the surface. These chambers create dead air spaces that reduce thermal conductivity (U-value: 2.3–3.1 W/m²K) while allowing light diffusion through the transparent PC walls. The walls are ribbed internally to enhance load capacity – some grades withstand snow loads up to 1.5 kN/m². Advanced versions integrate prismatic light-redirecting surfaces in the upper chambers, distributing sunlight evenly beneath the panel. This optical control reduces glare and hot spots, a critical feature for greenhouse applications where uniform plant growth is required. The hollow structure also provides natural sound insulation (up to 25 dB noise reduction).

Key Features

Weather resistance is exceptional, with UV-protected sheets maintaining mechanical properties for 10–15 years outdoors. The material's thermal expansion coefficient (0.065 mm/m°C) requires specialized mounting systems with expansion slots. Fire-retardant grades (UL94 V-2/V-0) are available for commercial projects. Unlike solid panels, the hollow design reduces material usage by 40% while maintaining stiffness. This makes the sheets economically viable for large-area coverage. Some manufacturers offer co-extruded layers with anti-condensation properties (hydrophilic coatings) to prevent water droplet formation in humid environments like swimming pool enclosures.

Application Areas

Industrial buildings account for 60% of usage, particularly in factory skylights where the sheets provide Class II fire-rated daylighting (EN 13501-1). In agriculture, the UV-diffusing properties prevent plant scorching while optimizing photosynthesis – a 2019 USDA study showed 18% higher crop yields compared to PE film greenhouses. Architects specify these sheets for curved canopy structures, taking advantage of the material's cold-bending capability (minimum radius ≈ 150× sheet thickness). Emerging applications include photovoltaic-integrated sheets, where the hollow chambers house micro-solar cells without compromising light transmission.

Maintenance and Precautions

Annual cleaning with isopropanol solution (≤40%) maintains light transmission. Avoid abrasive tools that may scratch the UV coating. For snow regions, install at ≥15° pitch with purlins spaced per manufacturer's load tables. Thermal movement calculations are critical – a 6m sheet expands ≈20mm between -30°C to +60°C. Always use EPDM-compressed sealing profiles rather than silicone, which degrades PC surfaces. In coastal areas, specify marine-grade aluminum end caps to prevent saltwater ingress into chambers.

B2B Procurement Guide

Order lead times typically range 2–4 weeks for custom colors/coatings. Key specifications to confirm: light transmission percentage (milky white sheets average 50%), impact resistance (IK rating), and warranty duration (premium brands offer 10-year warranties). Bulk buyers (≥500m²) can request chamber geometry modifications – some factories produce trapezoidal chambers for higher load-bearing. For projects requiring thermal breaks, some suppliers offer hybrid PC-aluminum composite panels with improved U-values (1.8 W/m²K). Always request third-party test reports for crucial parameters like hail resistance (FM 4470 standard).