Solar Cells: Classification and Generations
The world of solar cells is vast and complex. Since the discovery of the photovoltaic effect, numerous manufacturing technologies have been developed and existing production concepts continuously improved.
This article provides an overview of the various solar cell generations and explains the difference between P-type and N-type cells.
The Four Generations of Solar Cells
In scientific terms, solar cell technologies are classified into four successive generations:
1st Generation: Crystalline Silicon Cells
| Technology | Max. Efficiency (Laboratory) | Market Status |
|---|---|---|
| Monocrystalline | 26–27% | Established |
| Polycrystalline | 22–23% | Established |
- Oldest and most widespread technology
- 97% market share in global cell production (2023)
- Proven technology with long lifespan
2nd Generation: Thin-Film Cells
| Technology | Max. Efficiency (Laboratory) | Characteristic |
|---|---|---|
| Amorphous Silicon (a-Si) | 13–14% | Flexible, affordable |
| Cadmium Telluride (CdTe) | 22–23% | Low-cost production |
| CIGS | 22–23% | Flexible, thin |
- Significantly thinner cells (a few micrometres)
- Lower material consumption
- More flexible applications possible
3rd Generation: Emerging Technologies
| Technology | Max. Efficiency (Laboratory) | Status |
|---|---|---|
| Perovskite | 25–26% | Research |
| Organic Cells (OPV) | 18–19% | Research |
| Tandem Cells | 45% | Laboratory |
- Highest efficiency potential
- Not yet fully market-ready
- Intensive research worldwide
4th Generation: Hybrid Technologies
| Technology | Max. Efficiency (Laboratory) | Characteristic |
|---|---|---|
| Graphene Cells | ~26% | Combines multiple approaches |
- Unites advantages of various generations
- Still in early development phase
P-Type vs. N-Type Solar Cells
Beyond technology, solar cells can also be distinguished by their construction type:
What Do P and N Mean?
The letters refer to the doping of the base material:
| Type | Doping | Main Charge Carriers | Base Material |
|---|---|---|---|
| P-Type | P-doped (e.g. boron) | "Holes" (electron deficiency) | Thicker P-layer |
| N-Type | N-doped (e.g. phosphorus) | Electrons (surplus) | Thicker N-layer |
P-Type Solar Cells
Advantages:
- Established manufacturing processes
- Lower production costs
- Broad availability
Disadvantages:
- Light-induced degradation (LID)
- Lower efficiency
- More sensitive to temperature
N-Type Solar Cells
Advantages:
- Higher efficiency
- Lower degradation
- Better low-light performance
- Longer lifespan
Disadvantages:
- More complex manufacturing
- Higher costs
- Lower market penetration (currently)
Trend: N-type cells are gaining increasing market share. The higher efficiency justifies the additional cost, particularly with limited roof space.
Efficiency Comparison
| Technology | Laboratory | Commercial | Trend |
|---|---|---|---|
| Monocrystalline (P-Type) | 26% | 20–22% | Stable |
| Monocrystalline (N-Type) | 27% | 22–24% | ↑ Rising |
| Polycrystalline | 23% | 17–19% | ↓ Declining |
| PERC | 24% | 21–23% | Stable |
| TOPCon | 26% | 22–24% | ↑ Strongly rising |
| HIT/SHJ | 27% | 22–24% | ↑ Rising |
| CdTe | 22% | 17–19% | Stable |
| CIGS | 23% | 15–18% | Stable |
| Perovskite | 26% | - | Research |
| Tandem | 45% | - | Research |
Which Technology for Which Application?
| Application | Recommended Technology | Reason |
|---|---|---|
| House roof | Mono N-Type (TOPCon/HJT) | Max. yield on limited space |
| Large open ground | Mono P-Type, CdTe | Cost efficiency |
| Balcony solar | Mono P-Type (PERC) | Value for money |
| Façade/BIPV | Thin-film, Perovskite | Flexibility, aesthetics |
| Mobile applications | Thin-film, OPV | Light, flexible |
Market Development
The solar industry is growing rapidly:
- 2009 → 2024: Number of PV systems in Germany quintupled
- 2023: 52,250 GWh solar electricity generated in Germany
- Share of electricity mix: approx. 12% (2023)
Technology Trends
- N-Type overtaking P-Type: TOPCon and HJT cells gaining market share
- Bifacial modules: Can utilise light from both sides
- Larger wafers: 182mm and 210mm becoming standard
- Perovskite-tandem: Highest efficiency gains expected
Conclusion
Summary: Crystalline silicon cells dominate with 97% market share. The trend is moving from P-type to N-type cells with higher efficiency. Thin-film technologies occupy niche applications, whilst perovskite and tandem cells offer the highest future potential. For homeowners, monocrystalline N-type modules (TOPCon/HJT) are the best choice for maximum yield.
Continue reading: In the next article Crystalline Silicon Solar Cells in Detail, you will learn everything about AL-BSF, PERC, TOPCon and HIT cells.
Sources
- Pastuszak, J.; Węgierek, P.: Photovoltaic Cell Generations and Current Research Directions. Materials 2022
- ITRPV: International Technology Roadmap for Photovoltaic
- Fraunhofer ISE: Photovoltaics Report