JCC Solar Encapsulation Film JCC-105P (UV-cut EVA Film)

JCC Solar Encapsulation Film JCC-105P is a thermally crosslinking ethylene-vinyl acetate film formulated with a UV-cut additive package for front-side encapsulation of crystalline silicon photovoltaic modules. The product is supplied in roll format with nominal thickness options of 0.45 mm and 0.50 mm. The vinyl acetate content is controlled within 28–33 wt% to balance crosslinking density, low-temperature flexibility, and melt flow during vacuum lamination. Spectral measurements according to ASTM D1003-21 indicate luminous transmittance above 90% in the 400–1100 nm band, while transmittance below 360 nm is suppressed to ≤5%. The film includes an organic peroxide curing system and a silane coupling agent to promote adhesion to glass and backsheet interfaces. Gel content after lamination at 145–155 °C for 12–18 min is specified above 80% when measured by ASTM D2765-16 Method A. Typical lot-release values for volume resistivity exceed 1×10^14 Ω·cm under ASTM D257-14 after cure. Initial yellowness index by ASTM E313-20 is controlled below 1.0; after 1,000 h of xenon-arc exposure under ASTM G155-13 Cycle 1, yellowing index should remain below 5.0 for the cured laminate.

What distinguishes JCC-105P from conventional high-transmittance EVA?

Conventional high-transmittance EVA encapsulants transmit a large fraction of near-UV radiation; at 360 nm transmittance is commonly reported in the 60–85% range. JCC-105P uses a dissolved UV-absorber package to shift the absorption edge to longer wavelengths, reducing transmittance at 360 nm to ≤5% and below 350 nm to ≤1%. This reduction changes the photochemical environment at the cell and backsheet surfaces. UV-induced yellowing of the EVA matrix, photolytic degradation of polyethylene terephthalate backsheets, and ultraviolet damage to cell passivation stacks are retarded. The trade-off is a loss of near-UV photon current in cell architectures that collect below 380 nm. Unlike UV-transparent EVA grades that use low-iron glass and minimal absorber content to maximize current, JCC-105P is designed for module designs where long-term optical stability and backsheet protection take precedence over short-wavelength quantum efficiency.

Compared with standard EVA, the UV-cut package also modifies the thermal and radiative environment at the cell surface. The absorber absorbs photon energy and dissipates it as heat; at high irradiance the local temperature rise is generally below 2 °C relative to UV-transparent EVA in published module-level thermal imaging. This is not a severe thermal penalty but can be observed in modules with poor rear-side heat dissipation. The absorber does not significantly alter gel fraction or bulk mechanical properties because it is dispersed at low loading, typically below 1 wt% of the film formulation. Published data for the exact concentration in JCC-105P is not disclosed in the supplier technical summary; batch infrared spectra may be required for incoming quality control.

In a production vacuum laminator, the cure profile of JCC-105P is governed by the decomposition kinetics of the peroxide initiator and the heat transfer path from the platen through glass, cell, backsheet, and rubber membrane. The useful processing window is narrow. Cure temperatures below 140 °C can yield gel content below 70%, leaving residual peroxide and under-cured zones that exhibit creep and post-lamination shrinkage. Cure temperatures above 165 °C can produce void formation and increased adhesion to the laminator membrane because the melt phase is prolonged while the peroxide decomposition rate accelerates. A platen temperature setpoint of 145–155 °C is therefore specified, with platen uniformity of ±2 °C across the module area. Multi-chamber laminators with infrared preheating require a lower dwell time than single-chamber oil-heated machines; the actual dwell must be determined by thermocouple profiling of the laminate rather than by fixed residence time alone.

During vacuum lamination, the chamber is evacuated to 0.5 mbar or lower before membrane pressure is applied at 60–80 kPa. The pressing phase is typically held for 8–12 min before the module is cooled to 80 °C while still under vacuum to limit backsheet distortion. If the film has absorbed moisture, vapor bubbles can form at 0.5 mbar; rolls exposed to relative humidity above 70% should be reconditioned at 30 °C for 24 h in a dry-air cabinet before use. A melt mass-flow rate measured by ISO 1133-1:2022 at 190 °C and 2.16 kg is a useful incoming test, but the supplier-specified window is not a substitute for lamination trials because cell-string movement also depends on glass cleanliness, layup accuracy, and backsheet shrinkage. Free shrinkage at 150 °C for 15 min is controlled below 3% in both machine and transverse directions to limit edge pull-in on glass/backsheet modules.

After peroxide cure, the film develops a three-dimensional network. Tensile strength at break when tested by ASTM D882-18 is typically above 15 MPa, with elongation at break between 300% and 500%. The elastic modulus at 25 °C is typically below 10 MPa, which allows the encapsulant to accommodate thermal expansion mismatch between glass and silicon. These values are class-typical for EVA with vinyl acetate content in the specified range and are not materially changed by the UV-absorber package at loadings below 1 wt%. The cured film must also retain impact resistance; falling-ball impact tests on laminated glass configurations are generally performed at module level according to IEC 61215-2 rather than on the film alone.

Adhesion, damp-heat stability, and electrical insulation limits

The cured encapsulant must maintain adhesion to low-iron rolled glass and backsheet or rear glass under 1,000 h damp-heat exposure at 85 °C and 85% RH, as referenced in IEC 61215-2. Initial peel adhesion to glass after lamination is typically above 60 N/cm when tested by ASTM D1876-01; however, the dominant long-term failure mode is not cohesive fracture but interfacial hydrolysis and backsheet delamination. After damp-heat exposure, retention values of 50–70% are representative for EVA of this class, but the specific retention depends on backsheet chemistry, glass surface treatment, and the level of residual peroxide remaining after lamination. JCC-105P contains a silane coupling agent to stabilize the glass interface, but silane adhesion promotion cannot compensate for insufficient cure or contaminated glass.

Electrical insulation after cure is specified by volume resistivity above 1×10^14 Ω·cm under ASTM D257-14. This value supports module-level leakage current limits during wet-leakage testing, but the encapsulant is only one component in the electrical stack; backsheet dielectric strength, edge sealing, and glass surface contamination also contribute. In high-string-voltage arrays, potential-induced degradation can occur when sodium ions from the front glass migrate through the encapsulant. EVA has higher ion mobility than POE, and despite its electrical resistivity, JCC-105P does not provide the same ion barrier as a POE or ionomer encapsulant. Modules deployed in high-humidity coastal or agricultural environments should therefore be evaluated for PID resistance at the module level rather than relying on the encapsulant alone.

Acetic acid release remains a material-specific limitation of all EVA encapsulants. Under damp-heat conditions, vinyl acetate hydrolysis generates acetic acid that can corrode solder-coated cell interconnects and module frame components. The UV-cut absorber in JCC-105P does not eliminate this degradation pathway. In module designs with corrosion-sensitive metallization, backside passivation layers exposed to acid vapor, or long service lifetimes above 25 years, the use of POE or EVA/POE composite configurations should be considered for the cell-side layer. Published data comparing acetic acid generation rates between JCC-105P and standard EVA is limited; the relevant difference is not the UV absorber but the vinyl acetate content and cure conversion.

The following table compares representative values for JCC-105P, a standard high-transmittance EVA encapsulant, and a peroxide-crosslinked polyolefin elastomer grade. Values are class-typical ranges from publicly available material data; they are not lot-specific certificates of analysis and must not be used for production release without supplier confirmation.

The primary difference revealed by this comparison is the spectral cutoff. JCC-105P intentionally sacrifices near-UV transmittance to reduce photochemical stress, whereas standard high-transmittance EVA maximizes photon transfer at the cost of greater UV exposure. POE provides lower water-vapour transmission and a higher volume resistivity after cure, but it generally has higher material cost and can require longer lamination times when formulated with peroxide curing. JCC-105P is therefore selected when UV protection and EVA process compatibility are the dominant design constraints, while POE is selected when the module must limit acetic acid generation and moisture ingress over extended service.

When ultraviolet-responsive cell architectures are paired with UV-cut EVA

Some cell technologies, including certain heterojunction structures and thin-film junctions, rely on absorption in the 360–400 nm band to generate current. For these device stacks, the ≤5% transmittance of JCC-105P below 360 nm can reduce short-circuit current density. Published module-level quantum efficiency comparisons for UV-responsive cells indicate that replacing a UV-transparent EVA with a UV-cut EVA can lower near-UV response by 2–5% absolute in that spectral band. The effect on total module power is smaller because the photon flux below 380 nm is a minor fraction of the AM1.5G spectrum. For passivated emitter and rear cell architectures with front-side emitters that collect primarily in the visible and near-infrared, the current-density penalty is commonly below 1% and may be within measurement uncertainty. Published data for JCC-105P in specific heterojunction or perovskite tandem configurations is limited; therefore, module-level qualification under IEC 61215-2 and quantum efficiency mapping are required before production deployment.

For bifacial modules, JCC-105P is generally limited to the front side. The rear face of a bifacial module receives reflected near-UV radiation from ground surfaces and benefits from a UV-transparent EVA or POE. If JCC-105P is used on both faces of a bifacial structure, the rear-side current contribution can be reduced by the same spectral filtering effect. This is not a product defect but a mismatch between the optical filtering function and the bifacial optical design target. In glass/backsheet monofacial modules, the film is used as the front-side encapsulant directly above the cell; a separate backsheet-side EVA or bonding layer may be used, but the backsheet-side layer does not require the same UV-cut function if the front layer absorbs the UV before it reaches the backsheet interface.

Storage and handling limits apply to the roll. The material should be kept at 0–30 °C and 30–70% RH in original packaging, away from direct sunlight. Storage beyond 6 months can reduce peroxide activity and shift the gel-content curve, particularly if the roll has been exposed to temperature cycling. Rolls showing condensation or packaging damage should not be loaded into the laminator until reconditioning at 30 °C for 24 h in a dry environment has been completed. The film should not be placed on surfaces containing silicone oil or amine-functional silane residues; these contaminants can inhibit peroxide cure or migrate to the glass interface and lower peel strength. In single-chamber laminators with a platen area of 2.2 m × 1.1 m, the main production bottleneck is edge-to-center thermal lag during the ramp to cure temperature. Corner thermocouples placed 15 cm from each platen edge are recommended to detect the point at which the coldest module region enters the specified 145–155 °C window; the dwell timer should start from that event rather than from platen setpoint achievement.