Grading Retired PV Modules: How EL Gives End-of-Life Modules a Second Opinion

The first wave of large-scale PV systems built around 2010 reached 15 years of service in 2025. Europe's even earlier FIT-era farms are arriving at end-of-design-life around the same time. The first structural wave of PV module retirement has begun.

But "retired" is not "scrap." A large share of retired modules have degraded only 10%–15% — nowhere near failure. In emerging markets across Latin America, Southeast Asia and Africa, second-life PV is a real, growing business. Modules that truly cannot be refurbished go to recycling lines for silicon, silver, copper and aluminum recovery.

The hard question: how do you decide which category a given retired module belongs to? This is the single most important decision in the end-of-life PV business. This article lays out an EL-based grading framework.

1. Three Destinations for a Retired Module

Refurbish

• Degradation ≤20%

• No visible cracks or hotspots

• Intact EVA encapsulation — no large-area yellowing or delamination

• Acceptable appearance (light scratches allowed)

After cleaning, re-testing, and certification, these modules enter the second-life market — distributed projects, rural electrification, SME self-consumption in Latin America, Africa, and Southeast Asia.

Recycle

• Degradation >30% or severe internal defects

• Visible EVA delamination, severe PID, or burned-through hotspots

• Unfit appearance (extensive bubbles, scorch marks)

These modules enter recycling: glass recovery, aluminum frame, silicon wafer (chemical re-purification), silver finger recovery. A single module typically yields USD 2–5 in raw material value.

Discard

• Glass broken, backsheet torn

• Not safely transportable

These modules are handled as hazardous waste on site.

The central question: the refurbish-vs-recycle split is driven primarily by combined EL imaging + I-V electrical testing.

2. Why EL Sits at the Core of Grading

Multiple inspection techniques exist for retired modules, but EL plays a role nothing else can:

Refurbish grading isn't just about "how much power does it make now" — it is about "how long will it keep making that power." EL is the only technique that answers both current state and future risk.

Specific EL patterns map to specific grades:

• Uniform image, no visible defects — degradation from normal aging, suitable for refurbish

• Mild dark corners or dark edges — encapsulation aging without hotspot progression, refurbishable at Grade B

• Clear linear cracks, dark lines — mechanical damage has occurred, not recommended for refurbish, go to recycle

• Large-area dark patches, snake-line patterns — severe PID or cell-level failure, recycle only

3. A Working Grading Standard

Combining IEC 61215 / IEC 61730 recycling-relevant guidance with MVCreate's project experience, we propose the following four-grade standard.

Grade A — Refurbish without restriction

• Degradation ≤15%

• EL clean (dark corner <1%, no cracks)

• Appearance intact

• Resale price ~30%–40% of new

Grade B — Refurbish with restriction

• Degradation 15%–25%

• Mild dark corner/edge visible in EL (≤3%), no through-cracks

• Light scratches allowed

• Resale price ~15%–25% of new

• Recommend for low-capacity, non-critical applications (rural lighting, off-grid self-consumption)

Grade C — Partial reuse / partial teardown

• Degradation 25%–40%

• Clear localized defects in EL but cells mostly intact

• Recommend cell-level teardown and re-lamination — extract healthy cells and build new modules

Grade D — Recycle directly

• Degradation >40%, or pronounced snake / large-area dark patterns in EL

• Visible encapsulation or glass damage

• Direct to recycling line

This standard requires EL imaging + I-V testing together — neither alone is sufficient.

4. SC-DEL-Portable in a Refurbishment Line

A typical refurbish-line workflow:

Module intake → Visual → EL full scan → I-V test → Grade & label → Clean/refurbish → Repackage → Ship
                          ↑
                    SC-DEL-Portable

At the EL full-scan stage, SC-DEL-Portable fits because:

1. Daylight-capable — no darkroom required, the refurbishment line can run a normal daytime shift;

2. Portable — 5 kg main unit, moves to the module rather than forcing the module to a fixed camera;

3. Throughput — 800 modules/day keeps pace with a medium refurbishment line (500–600 modules/day);

4. Data integration — results stream over Ethernet or Wi-Fi to MES or LIMS for grading decisions.

5. A Complete End-of-Life Case

Project: A Chinese investment group acquired 12 MW of retired PV modules from a 2010-vintage utility farm — 56,000 multicrystalline modules total.

Grading workflow:

1. Visual screen — ~4% rejected immediately (glass or backsheet damage) → Grade D

2. SC-DEL-Portable EL full scan — completed in 15 days

3. I-V test — cross-validated with EL

4. Final grade distribution:

Economics:

• A + B resale: ~USD 2.5M

• C cell teardown / remanufacture: ~USD 600k

• D recycling: ~USD 250k (Si, Ag, Cu, Al)

• Grading + refurbishment cost: ~USD 900k

• Net profit ~USD 2.45M

EL inspection accounted for ~4% of total cost, yet it was the decisive factor in A/B/C/D classification. The cost of misclassification far exceeds the inspection cost itself.

6. Three Trends to Watch

Trend 1: From gray market to regulated

Retired modules used to flow through undocumented gray channels. Over the next 3–5 years, Grade B second-life modules with full EL + I-V documentation will become mainstream and push the gray market out.

Trend 2: Carbon footprint as an export requirement

EU CBAM (Carbon Border Adjustment Mechanism) tightens carbon footprint requirements on PV-related products. Refurbished modules have roughly 15% the footprint of new modules — a natural export advantage, provided inspection data can prove it.

Trend 3: Grading data enters the digital product passport

EU DPP from 2027 requires every new PV module to carry a digital identity. Retired modules with retrofit "end-of-life grading + EL record" can join that digital circulation chain.

Closing

Grading retired modules isn't waste management — it is putting ten more years of energy capacity back into the market. EL answers both "how is it now" and "how will it hold up" in one technique. MVCreate's SC-DEL-Portable brings industrial-grade grading capability to refurbishment lines in a 5 kg form factor.

For retired-module line design, reach out to the MVCreate technical team (+86 159-5048-9233).

Website: www.mvcreate.com

Originally published by Vision Potential / MVCreate.