As storage system voltages rise to the 1000–1500 V class, busbar holders, connectors and sensing assemblies become more sensitive to creepage distance and tracking.
Advice · Candidates
Advice
State the CTI target (tested to IEC 60112) and glow-wire requirements (GWFI / GWIT) in the material specification. Reinforced PA and PBT usually reach a high CTI more easily than amorphous materials. Both color and flame retardant affect CTI, so test in the actual color.
Cells are getting larger and more densely packed, and brackets and separators are getting thinner. Many materials reach V-0 at 1.5 mm but not at 0.8 mm.
Advice
First set the flammability target at the thinnest point. PC and PC/ABS systems char easily when burning, so they reach V-0 halogen-free fairly easily. When thinner walls are needed, choose high-flow grades and validate with specimens at the actual wall thickness.
Structural parts: stiffness, creep and swelling force
Pain point
Cells swell during charge, discharge and aging. End plates and side plates carry loads long-term and creep easily.
Advice
Choose glass-fiber-reinforced materials and check creep against long-term load and operating temperature. Watch the anisotropy from fiber orientation, and design the gate position together with the load direction. Nylon absorbs moisture, so use conditioned values for design.
Outdoor and residential: weathering, appearance and drop
Pain point
Outdoor cabinets face sun for years, and standard ABS and PC/ABS yellow and become brittle. Residential and portable products need good appearance and must also pass drop tests.
Advice
Set xenon-arc weathering tests for outdoor parts by target region, and judge by color difference and impact retention after aging. For portable products, look at both room- and low-temperature notched impact. Color match appearance parts at the compounding stage, which is more even than adding masterbatch at molding.
Sustainability: halogen-free, fluorine-free and recycled content
Pain point
Export brands require halogen-free; some customers require no PTFE anti-drip agent; brands also want more recycled content.
Advice
Halogen-free is usually judged against the halogen limits of IEC 61249-2-21 or your specification, and needs a third-party test report. Fluorine-free needs a clear statement on whether PTFE is allowed. Recycled material brings batch variation, so validate several batches before introducing it into mass production.
Recycled versions of each grade (suffix -R), with the recycled share set per project
Certificate to be uploaded
Material selection for plastic parts in energy storage systems (utility, C&I and residential), portable power stations, power banks, PCS / inverters and charging equipment.
Flammability ratingUL 94 · 1.5 mm; design target, subject to test report
HB
Processing
Drying
100–110 °C, 3–4 h
Melt temperature
250–280 °C
Mold temperature
60–90 °C
Why this material
UV resistant, color stable, resists yellowing
Industry overview and trends
Energy storage is entering large-scale deployment
In 2025, new energy storage installed worldwide (excluding pumped hydro) exceeded 100 GW, about 300 GWh, up more than 40 % on the previous year. The industry expects further growth in 2026. China accounts for more than half of new installations worldwide.
Battery technology is mainly LFP
Lithium iron phosphate (LFP) batteries make up about 90 % of new energy storage projects. LFP is low cost with long cycle life, suiting storage that charges and discharges every day.
Larger cells, more compact systems
Energy storage cells have moved from the 280 Ah class to the 314 Ah class and are now heading above 500 Ah. One 20-foot container already holds more than 6 MWh. With larger, more densely packed cells, brackets, end plates and insulating parts must carry more weight and swelling force while getting thinner.
Safety standards keep tightening
Mandatory safety standards for energy storage batteries are in force. Overseas projects generally require system-level certification and thermal runaway propagation tests. Plastic parts are not the source of thermal runaway, but they affect flame spread, electrical insulation and structural integrity. So project owners are writing material flammability, comparative tracking index (CTI) and glow-wire performance into material specifications ever earlier.
Environmental requirements are rising
Export brands generally require halogen-free flame retardancy. The EU is reviewing a universal PFAS restriction proposal under REACH (still a proposal as of October 2026, not yet adopted). The commonly used PTFE anti-drip agent is a fluoropolymer and is therefore drawing attention, and some customers have started to require "halogen-free and fluorine-free". Brands' carbon reduction targets are also driving the use of post-consumer recycled material (PCR).
Residential and portable products care more about appearance and feel
Residential storage units and portable power stations sit in homes or cars. Housings must be flame-retardant and drop-resistant, with uniform color and a fine surface finish. Outdoor cabinets also need long-term resistance to sunlight, heat and humidity.
Energy storage is now deployed at large scale. In 2025, global new storage additions (excluding pumped hydro) exceeded 100 GW, about 300 GWh. This is more than 40 % higher than the year before.
Cells are getting larger. Cell capacity has moved from the 280 Ah class to the 314 Ah class and is now moving above 500 Ah.
Safety standards are getting stricter. Plastic parts do not start thermal runaway. But they affect flame spread, electrical insulation and structural integrity.
Many export brands ask for halogen-free flame retardants. The EU is reviewing a universal PFAS restriction proposal under REACH. As of October 2026 it is still a proposal. Some customers now also ask for fluorine-free grades (no PTFE anti-drip agent).
Residential and portable products need flame retardancy, drop resistance and good appearance. Outdoor cabinets need UV and humidity resistance.
Part-to-material guide
Full list · 14 parts
This table shows common industry practice for first-round selection. The final choice depends on the applicable standards, the actual wall thickness and validation results (to be verified by GREENPOLYMER).
Heat and impact resistant; outdoor models need UV resistance
Key requirements
V-0 or 5VA (per enclosure requirements); UV and outdoor suitability (f1); low-temperature impact
Common standards
UL 94; UL 746C; IEC 62477-1; IEC 62109-1 (PV inverters)
GREENPOLYMER grade
GRN-PC-N510; GRN-PCA-N510; indoor appearance parts can use GRN-PCA-W310 (HB, non-flame-retardant). Outdoor weather resistance + flame retardancy: Available as a project-based development
Color difference and impact retention after xenon-arc weathering; low-temperature impact
Common standards
ISO 4892-2; UL 746C (f1)
GREENPOLYMER grade
GRN-PCA-W310 (design target: ΔE ≤ 3 after 1000 h of xenon-arc weathering, to be verified by GREENPOLYMER). GRN-ASA-W110 (weather-resistant ASA); GRN-PCAS-W310 (weather-resistant PC/ASA)
Outdoor use, impact and low-temperature resistant; the connector head is close to terminals, so heat resistance and high CTI are needed
Key requirements
V-0; low-temperature impact (such as −30 °C); UV; CTI; chemical resistance
Common standards
UL 94; UL 746C; IEC 62196-1; GB/T 20234.1
GREENPOLYMER grade
Housing: GRN-PC-N510, GRN-PCA-N510; parts inside the connector head: GRN-PA6-E510. Weather-resistant flame-retardant PC: Available as a project-based development
Example grade / typical values — to be corrected by GREENPOLYMER
Notes
A flammability rating is valid only at the stated thickness. Check the thinnest wall of the part.
UL 9540, UL 1973, IEC 62619 and GB 44240 apply to the battery or the system, not to the material itself. For the enclosure flammability requirement of GB 44240, see its clause 9.2.
UL 9540A is a test method for thermal runaway fire propagation. It is done at cell, module or unit level.
Carbon-fiber-reinforced grades may conduct electricity. Do not use them as insulators without checking.
GREENPOLYMER does reinforcing, toughening, filling and blending. Formulations can be adjusted to the part's flammability, CTI, heat resistance, impact and appearance requirements. Materials marked "Available as a project-based development" in the table can be developed with GREENPOLYMER engineers.
Halogen-free flame retardancy
GREENPOLYMER's flame-retardant technology focuses on halogen-free and fluorine-free solutions. Silicone-based flame-retardant grades do not use PTFE anti-drip agents.
Color matching
The Shenzhen Color Matching Center works to RAL and Pantone numbers and customer color plaques, including the orange often used for high-voltage parts. Color matching at the compounding and pelletizing stage keeps color more stable from batch to batch.
Recycled grades
Each grade can be customized with recycled content (suffix -R). The recycled share is set per project, with traceability documents. Certificate to be uploaded.
Fast sampling
Free samples of 1–5 kg are available for standard grades, usually shipped in 3–7 working days. Custom formulation samples usually take 1–3 weeks.
Sites
The company headquarters and main plant are in Jiangxi, which is also home to a 3D printing filament industry cluster. GREENPOLYMER also has the Hangzhou Production Base, the Shenzhen Color Matching Center and the Dongguan Development Center. 6,000+ t capacity; 29,000+ m² total plant area.
Patents
8 invention patents.
In-house testing
Test equipment covers melt flow rate, Izod and Charpy impact, horizontal and vertical burning (UL 94 method), heat deflection temperature and Vicat, constant temperature and humidity, UV and xenon-arc weathering, XRF, TGA, DSC, glow-wire, needle flame, comparative tracking index (CTI) and salt spray. In-house tests are for development and quality control and do not replace third-party test reports or UL certification.
Customers and partners
EcoFlow, BigBlue (portable power stations, power banks); Yadea (e-bikes and two-wheelers).
3D printing in energy storage
Energy storage products change fast. 3D printing helps verify designs before tooling.
Use
Example
Recommended filament
Structural prototypes
Cell holder layout validation, end plate assembly validation, housing prototypes
GRN3D-PCA-E01 (PC/ABS); GRN3D-ABS-E01; housing samples needing a flame-retardant formulation: GRN3D-PC-X01 (flammability rating of printed parts to be verified by GREENPOLYMER)
The flammability of printed parts is not the same as that of injection-molded parts from pellets. Flammability results or certifications of pellets cannot be applied directly to filament or printed parts.
The properties of printed parts depend on print orientation, layer thickness and infill. Test functional parts as actually printed.
Carbon-fiber-reinforced filaments may conduct electricity and cannot be used for insulation validation of live parts.
Q1. Should I use PC/ABS or PC for ESS cell holders?
Halogen-free FR PC/ABS works for most cell holders. It flows well and suits thin walls with many holes. Choose FR PC when the part needs higher heat resistance or higher impact strength. Confirm with flame tests at the actual wall thickness and with temperature-rise data.
Q2. If the material is UL 94 V-0, will the ESS pass UL 9540?
No, not automatically. UL 9540 and UL 9540A evaluate the system and the unit. The UL 94 rating of the material is only one input. Enclosures may also need UL 746C evaluation. Write the system requirements into your material specification early.
Q3. What CTI do busbar holders and connectors need?
The CTI target depends on the working voltage, the pollution degree and the creepage design. A high CTI class is common. Put the target value and the test method (IEC 60112) in your specification. GREENPOLYMER can recommend or develop a grade for your color and CTI target. Ask us for the test report of each grade (to be verified by GREENPOLYMER).
Q4. What is the difference between halogen-free and PTFE-free?
Halogen-free is usually judged by the limits in IEC 61249-2-21. Those limits cover only chlorine and bromine, not fluorine. PTFE is an anti-drip agent used in many FR compounds, and it contains fluorine. So a material that is halogen-free under that standard is not always fluorine-free. If you need fluorine-free, choose a grade without PTFE and ask for the test report.
Q5. Can you make flame-retardant grades with recycled content?
Yes. GREENPOLYMER can make FR grades with recycled content (suffix -R) if the performance targets are met. The recycled ratio is set per project. Traceability documents are provided. Recycled feedstock varies more between batches, so please test several batches. Certificate to be uploaded.
