The Manufacturing Chain
- Polysilicon Production: Siemens process — purify metallurgical-grade silicon to 99.9999% (6N) purity. Fluidized bed reactor (FBR) is newer, lower-energy alternative.
- Ingot Growth: Czochralski (Cz) for monocrystalline — single crystal seed pulled from melt. Directional solidification for polycrystalline — lower cost, lower efficiency.
- Wafer Slicing: Diamond wire sawing. Current thickness: 130-160μm. Kerf loss: 60-80μm. Trend toward thinner wafers.
- Cell Processing: Texturing → Diffusion (p-n junction) → Edge isolation → Anti-reflection coating (SiNx) → Metallization (screen printing Ag/Al paste) → Firing.
- Module Assembly: Stringing → Layup → Lamination (EVA/POE + Backsheet) → Frame mounting → Junction box → Flash testing → Labeling.
Six Generations of Cell Technology
| Generation | Technology | Typical Efficiency | Key Feature |
|---|---|---|---|
| 1st | Al-BSF (mono-Si) | 15-17% | Full area Al back surface field |
| 2nd | Poly-Si | 16-18% | Lower cost, blue color |
| 3rd | PERC | 20-22% | Passivated rear with laser openings |
| 4th | TOPCon | 24-25% | Tunnel oxide passivated contact |
| 5th | HJT | 25-26% | Amorphous Si on crystalline Si |
| 6th | Perovskite Tandem | 27-33% (lab) | Perovskite on Si — future tech |