Embodied Energy of PV
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- How much energy required to make a Watt of PV? [1].
Fraunhofer study - 1 year payback time, meaning 20x energy EROI over 20 years. [2]
Embodied Energy of PV
| Component | Description | Typical Embodied Energy Share (% of module) | Approx. Material Weight Required per 1 MW of Finished PV Panel |
|---|---|---|---|
| Silicon Feedstock & Ingot | Quartz → polysilicon → crystal growth (Czochralski or similar) | 25–40% | ~1.3–1.6 t silicon in finished modules (upstream feedstock needed is 30% higher after kerf/yield losses) |
| Wafering | Slicing ingots into wafers (kerf loss, sawing energy) | 10–20% | N/A — process step, not a distinct added bulk material |
| Cell Processing | Doping, diffusion, etching, deposition (PECVD), metallization | 15–25% | N/A — process step, not a distinct added bulk material; added metallization mass is small relative to module mass |
| Glass (Front Sheet) | Tempered low-iron solar glass (~3–4 mm) | 10–20% | ~31–39 t |
| Encapsulant (EVA/POE) | Polymer layers for lamination | 3–8% | ~3.1–3.9 t |
| Backsheet (or rear glass if bifacial) | Polymer backsheet or second glass layer | 3–10% | ~1.7–2.1 t for polymer backsheet modules; much higher for glass-glass modules |
| Aluminum Frame | Extruded frame + finishing | 5–15% | ~5.9–7.4 t |
| Junction Box & Wiring | Diodes, copper wiring, connectors | 2–5% | ~2.0–2.5 t (junction box polymers, silicones, copper interconnects, cables, solder, diodes combined) |
| Module Assembly | Lamination, curing, handling, factory overhead | 3–8% | N/A — assembly step, not a distinct bulk material |
| Total | ~100% | ~46–58 t of finished module mass per MW |
For Upgraded Metallurgical Grade Silicon
About 30% lower overall energy requirement over standard PV.
| Component | Description | Typical Embodied Energy Share (% of module, UMG silicon) |
|---|---|---|
| Silicon Feedstock & Refining (UMG) | Metallurgical silicon upgraded via slag refining / directional solidification (no Siemens process) | 10–20% |
| Ingot Growth | Crystal growth or casting (lower purity requirements than electronic-grade) | 10–20% |
| Wafering | Slicing or kerfless wafer production | 10–20% |
| Cell Processing | Doping, diffusion, passivation, metallization | 20–30% |
| Glass (Front Sheet) | Tempered low-iron solar glass (~3–4 mm) | 15–25% |
| Encapsulant (EVA/POE) | Polymer layers for lamination | 5–10% |
| Backsheet / Rear Glass | Polymer backsheet or second glass layer (bifacial increases share) | 5–15% |
| Aluminum Frame | Extruded frame + finishing | 8–18% |
| Junction Box & Wiring | Diodes, copper wiring, connectors | 2–5% |
| Module Assembly | Lamination, curing, factory overhead | 5–10% |
| Total | ~100% |