What is p-type silicon
P-type silicon is crystalline silicon intentionally doped with a small concentration of boron atoms (typically 10^15 to 10^17 atoms/cm³). Boron has three valence electrons (one less than silicon’s four), creating “holes” or electron deficiencies that act as positive charge carriers. The result: silicon with hole carriers (p for positive).
P-type silicon has been the traditional base material for solar cells since the early decades of PV. PERC (Passivated Emitter and Rear Contact) cells, which dominated solar from 2017 to 2024, are built on p-type wafers. Earlier cell technologies (BSF, Al-BSF) also used p-type.
The Indian solar industry’s gradual transition to n-type TOPCon from 2024 onward marks the end of p-type’s dominance. P-type will persist in legacy installations, cost-sensitive markets and gallium-doped variants for the next several years, but new manufacturing capacity is increasingly n-type.
Why p-type matters
Legacy installed base. Hundreds of GW of PERC p-type modules installed globally and in India.
Cost. P-type wafer manufacturing is mature and slightly cheaper than n-type.
Replacement supply. Existing PERC arrays need matching modules for repairs.
Cost-sensitive segments. Gallium-doped p-type offers efficiency gains without n-type premium.
Historical understanding. P-type technology informs ongoing cell development.
How p-type works
- Czochralski crystal growth with boron dopant added to silicon melt.
- Ingot grown by slow pulling from melt.
- Ingot sliced into wafers.
- Wafers processed through PERC manufacturing flow.
- Final cell: p-type base, n-type emitter on front, PERC rear passivation.
Technical deep dive
Comparison: p-type vs n-type
| Property | P-type | N-type |
|---|---|---|
| Dopant | Boron (or Gallium) | Phosphorus |
| Charge carriers | Holes | Electrons |
| LID | Significant (B-O) | None |
| LeTID | Present | Minimal |
| Bulk lifetime | Lower | Higher |
| Temperature coefficient | -0.36%/°C | -0.30%/°C |
| Cost | Baseline | 3-8% premium |
| Cells | PERC, BSF | TOPCon, HJT, IBC |
| Efficiency ceiling | ~23% PERC | 26%+ HJT |
Boron-oxygen LID
P-type silicon with boron and dissolved oxygen forms boron-oxygen (B-O) complexes under light. The defects trap charge carriers, reducing efficiency by 1-2.5 percent in the first 100 hours of operation — the same mechanism covered in the LID entry. Gallium-doped p-type silicon eliminates this mechanism.
Cell technologies using p-type
Traditional polycrystalline wafers were also p-type, though most of that capacity has since shifted to mono PERC or TOPCon lines.
| Cell | Status |
|---|---|
| BSF (Al-BSF) | Legacy, largely retired |
| PERC | Dominant 2017-2024, declining |
| Gallium-PERC | Low-LID variant |
| n-PERC (rare) | n-type with PERC structure |
Real-world applications
Legacy PERC installations, though showcase floors are shifting fast toward n-type panels (see REI Expo 2026 preview: what to look for).
ALMM-listed PERC modules.
Cost-sensitive utility and rooftop projects.
Spare module supply for repair.
Advantages
Lower wafer cost.
Mature manufacturing infrastructure.
Established processing knowledge.
ALMM-listed broadly.
Limitations
LID losses.
LeTID concern in some PERC variants.
Lower efficiency ceiling.
Worse temperature performance, which shows up as measurable yield loss during Indian summer peaks (see Solar Yield in India, kWh-per-kW Benchmarks by State).
Lower bifaciality than bifacial n-type modules.
Indian market context
P-type PERC dominated Indian module manufacturing from 2020-2024.
Major Indian PERC manufacturers transitioning to TOPCon n-type.
ALMM List I still includes p-type PERC modules; see ALMM List Phase III, Complete Guide for Buyers and EPCs 2026 for the latest listing rules.
PM Surya Ghar accepts both p-type and n-type modules.
Standards and certifications
| Standard | Scope |
|---|---|
| IEC 61215 | Module qualification |
| IEC 61730 | Module safety |
| IEC 62804 | PID test |
| IS 14286 | Indian module standard |
| MNRE ALMM | Listing |
Key takeaways
P-type silicon is boron-doped silicon traditionally used as the base for PERC solar cells. Dominant from 2017-2024, p-type is being replaced by n-type TOPCon for new manufacturing. Susceptibility to LID is the main technical limitation. P-type will persist in legacy and cost-sensitive segments for several years. Gallium-doped p-type addresses LID for those who prefer p-type’s cost advantage.
Further reading
For how P-Type Silicon plays out in real projects, these guides go deeper:
- On-Grid vs Hybrid vs Off-Grid: Decision Guide
- Solar Inverter Kya Hai? - पूरी जानकारी हिंदी में
- How to Choose Solar Inverters with Surge Protection
- ALMM List-II Exemption Window for Net Metering & Open Access
Sources
- IEC 61215, Module qualification.
- IEC 61730, Module safety.
- IEC 62804, PID test.
- IS 14286, Indian Standard.
- ITRPV Roadmap, latest edition.
- NREL Best Research-Cell Efficiency Chart.
- Green M. A., Silicon Solar Cells, Wiley.
- Sze S. M., Physics of Semiconductor Devices, Wiley.
- IEA PVPS Trends 2024.
Frequently Asked Questions
What is p-type silicon in simple words?
What dopant is used?
Why was p-type dominant?
Why is p-type declining?
Is p-type still used?
What is the efficiency ceiling?
What is gallium-doped p-type?
What is the temperature coefficient?
Does p-type have LeTID?
Is bifacial p-type viable?
What is the cost difference?
Are polycrystalline cells p-type?
Will p-type disappear?
Is PM Surya Ghar compatible with p-type?
What is the future of p-type?
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