Quick Facts
What POE is
POE (Polyolefin Elastomer) is a transparent polymer film used as the encapsulant in solar panels. The encapsulant surrounds the cells between the front glass and the rear cover (backsheet or rear glass), bonding the layers together while protecting the cells from moisture, mechanical stress, and UV exposure.
POE is the premium alternative to EVA (Ethylene Vinyl Acetate), the traditional industry-standard encapsulant. POE offers several advantages over EVA: superior moisture barrier, no acetic acid formation under humid conditions, better PID resistance, and slightly higher light transmission.
POE is increasingly used in premium solar modules, particularly:
Glass-glass bifacial modules (where POE’s moisture barrier and chemical stability matter most).
Modules for humid coastal climates (where EVA’s acetic acid issue is most problematic).
Premium and lender-grade installations (where long-term reliability justifies the cost premium).
Modules with n-type cells (TOPCon, HJT) for combined low-PID risk profile.
How POE differs from EVA
The two encapsulants have fundamentally different chemistry:
EVA: Ethylene Vinyl Acetate copolymer. Contains vinyl acetate groups that can hydrolyse under heat and humidity, releasing acetic acid. The acetic acid corrodes cell metallisation and ribbon interconnects over years.
POE: Polyolefin Elastomer. Saturated polyolefin chemistry without ester groups. Does not hydrolyse to produce acid. Chemically stable under humid conditions.
The chemistry difference translates to practical performance:
Moisture barrier: POE has lower water vapour transmission rate (WVTR), better protecting cells from humidity.
Acid formation: EVA produces acetic acid; POE does not. The acetic acid issue is particularly severe in glass-glass modules where moisture is trapped.
Electrical resistivity: POE has higher resistivity, reducing leakage currents that drive PID damage.
Light transmission: POE has slightly higher light transmission than EVA, especially in the blue and UV range.
For Indian conditions with high humidity and temperature, POE’s advantages are most pronounced.
Cost comparison
POE encapsulant costs more than EVA:
EVA: Reference cost.
POE: 30% to 60% higher cost per square metre.
For a typical 540 Wp solar module:
EVA encapsulant cost: Rs 200 to Rs 400.
POE encapsulant cost: Rs 300 to Rs 600.
Difference: Rs 100 to Rs 300 per module.
For a 5 kW residential system (12 modules): Rs 1,200 to Rs 3,600 extra cost.
For a 100 kW commercial system (220 modules): Rs 22,000 to Rs 66,000 extra cost.
The cost premium is meaningful but small relative to total project cost. Most premium installations consider the long-term reliability benefit worthwhile.
When to choose POE
The decision between POE and EVA depends on application:
Choose POE when:
The module is glass-glass bifacial (almost always; POE is the standard).
The installation is in humid coastal or monsoon-affected region.
The customer prefers premium quality for long-term ownership.
The cell technology is HJT (often specified with POE for combined reliability).
The project is lender-financed and reliability matters.
Choose EVA when:
The module is glass-backsheet monofacial (EVA is the standard).
The installation is in dry inland regions where humidity is low.
The customer prioritises lowest upfront cost.
The plant has shorter expected life (under 20 years).
For most Indian premium and lender-grade projects in 2026, POE is the preferred choice. For mass-market residential and commercial monofacial, EVA remains the standard.
EPE: hybrid encapsulant
EPE (EVA-POE-EVA) is a multi-layer encapsulant that uses POE in the middle with EVA on the outer faces. Designed to combine POE’s moisture barrier with EVA’s adhesion and cost.
EPE benefits:
Better moisture barrier than pure EVA (because the POE core blocks moisture).
Easier lamination than pure POE (EVA’s adhesion characteristics).
Lower cost than pure POE.
EPE is used in some premium products as a middle path. The full POE remains the highest-end choice for most demanding applications.
POE in glass-glass modules
For glass-glass bifacial modules, POE is essentially mandatory:
Both faces are sealed by glass. Any moisture or acetic acid trapped inside cannot escape.
EVA’s acetic acid in this sealed environment causes accelerated degradation.
POE does not produce acid; trapping moisture is much less consequential.
POE’s lower water vapour transmission keeps cells drier.
Almost all premium glass-glass bifacial modules specify POE encapsulant in their datasheets. Mixing EVA with glass-glass construction is generally a design error.
POE manufacturing and supply
Several major suppliers produce POE encapsulant:
Mitsui Chemicals: Japan-based premium POE supplier.
Bridgestone: Diversified into POE encapsulant manufacturing.
Shanghai Ji’an: Chinese supplier with significant capacity.
Hanwha Solutions: Korean supplier integrated with module manufacturing.
LG Chem: Korean supplier with high-quality POE products.
Indian module manufacturers source POE from these global suppliers, with growing Indian-made POE capacity under PLI scheme support.
Common mistakes regarding POE
Treating POE and EVA as equivalent. The chemistry difference matters significantly for long-term reliability.
Specifying EVA for glass-glass modules. The combination causes accelerated degradation through acetic acid formation.
Choosing budget POE without checking supplier. Premium POE from established suppliers outperforms generic alternatives.
Ignoring climate considerations. Coastal Indian installations need POE more than dry inland ones.
Forgetting EPE option. EPE provides middle-ground performance and cost.
Best practices
For glass-glass bifacial modules: specify POE encapsulant.
For coastal and humid Indian installations: prefer POE over EVA.
For premium installations with long-term ownership: POE delivers better lifecycle economics.
For lender-grade procurement: verify encapsulant type and supplier as part of due diligence.
For mixed module portfolios: use POE consistently to avoid mismatch in degradation rates.
Standards and references
POE encapsulant testing follows IEC 62788 series (testing of solar PV encapsulant materials). Module-level certification under IEC 61215 and IEC 61730 verifies the overall product including encapsulant. PID resistance per IEC 62804. Premium POE suppliers publish detailed technical data including accelerated aging results.
Related glossary terms
- EVA Encapsulant
- Fluoropolymer Backsheet
- Bifacial Solar Panel
- PID and Anti-PID
- TOPCon Solar Panel
- HJT Solar Panel
- IEC 61215 Standard
- Solar AR Glass
Key takeaways
POE (Polyolefin Elastomer) is a premium solar encapsulant offering superior moisture barrier, no acetic acid formation, better PID resistance, and slightly higher light transmission compared to EVA. POE is essentially mandatory for glass-glass bifacial modules where its chemistry matches the sealed construction. For Indian installations in humid coastal regions, POE significantly improves long-term reliability. The cost premium of 30% to 60% over EVA is meaningful but small relative to total project cost, making POE the standard choice for premium and lender-grade installations. EPE (EVA-POE-EVA multi-layer) provides a middle ground for some applications.