Solar Module Technologies: From Monocrystalline to Perovskite Tandem

The world of solar cells has evolved rapidly in recent years. From the classic polycrystalline module to the cutting-edge perovskite tandem cell — each technology has its strengths and optimal applications. This comprehensive guide explains the structure, manufacturing process and properties of all relevant solar cell technologies.

Comparison Table of All Technologies

As of January 2026 | Sources: Fraunhofer ISE, NREL Best Research-Cell Efficiencies

Technology↕	Type↕	Comm. eff.↕	Lab record↕	Temp. coeff.↕	Market share↕
Mono PERC	Crystalline	21.5%	24.1%	-0.35 %/°C	55%
Mono TOPCon	Crystalline	22.5%	26.4%	-0.30 %/°C	25%
Mono HJT	Crystalline	22.8%	26.8%	-0.26 %/°C	5%
Mono IBC	Crystalline	23%	26.7%	-0.29 %/°C	2%
Polycrystalline	Crystalline	17%	23.3%	-0.40 %/°C	5%
CdTe (Thin-film)	Thin-film	18.5%	22.1%	-0.25 %/°C	4%
CIGS (Thin-film)	Thin-film	16.5%	23.6%	-0.32 %/°C	1%
Perovskite	Emerging	0%	26.1%	variable	0%
Pero/Si Tandem	Emerging	0%	33.9%	variable	0%

Cell Cross-Section

The internal structure of a solar cell differs fundamentally depending on the technology. The following interactive diagram shows the layer structure of the most important cell types.

Zellaufbau im Querschnitt

Mono PERCTOPConHJT (Heterojunction)Dünnschicht (CdTe)PerowskitPerowskit/Si-Tandem

Sonnenlicht ↓

Glas (gehärtet)

n-Emitter

p-Basis (Mono-Si)

Aluminium-Rückkontakt

Backsheet

Schichten von oben nach unten:

Glas (gehärtet)

Schutz vor Witterung, >90% Lichtdurchlass

EVA-Folie

Einbettung und UV-Schutz

Antireflexschicht (SiNx)

Minimiert Reflexionsverluste auf <2%

n-Emitter

Phosphor-dotierte Schicht (n-Typ)

p-Basis (Mono-Si)

Bor-dotierter Monokristall-Wafer, ~170 µm

PERC-Passivierung (Al₂O₃)

Rückseitenpassivierung reduziert Rekombination

Aluminium-Rückkontakt

Lokale Kontaktöffnungen (LBSF)

Backsheet

Feuchtigkeitsschutz (TPT oder Glas)

Klicken Sie auf eine Schicht für Details. Maßstab nicht proportional.

Crystalline Silicon Technologies

Crystalline silicon cells form the backbone of photovoltaics with over 95% market share. They are based on high-purity silicon that is cut into wafers and processed into cells.

Monocrystalline PERC

PERC (Passivated Emitter and Rear Cell) has been the dominant technology since 2019 and forms the basis for most modules sold today.

Manufacturing process:

1. Czochralski method: single-crystal silicon is pulled from the melt
2. Wafers are sawn to ~170 um (diamond wire cutting)
3. Surface texturing (pyramid structure)
4. Phosphorus diffusion to form the p-n junction
5. PECVD deposition of the anti-reflection coating (SiNx)
6. Al2O3 rear-side passivation (the PERC-specific feature)
7. Laser contact opening on the rear side
8. Screen printing of silver front contacts and aluminium rear contacts

Applications: Private homes, small commercial, balcony power stations. PERC is suitable for virtually any standard installation and remains a solid choice in 2026.

Manufacturer examples: JA Solar (DeepBlue 3.0), Trina Solar (Vertex S), Canadian Solar (HiKu), Risen Energy

Monocrystalline TOPCon

TOPCon (Tunnel Oxide Passivated Contact) is the successor technology to PERC and has been produced in large volumes since 2024.

Manufacturing process:

1. Identical to PERC up to wafer production (n-type instead of p-type silicon)
2. Boron diffusion for the p-emitter (front side)
3. Ultra-thin tunnel oxide (~1.5 nm SiO2) on the rear side
4. Poly-Si deposition by LPCVD as rear contact
5. Phosphorus doping of the poly-Si layer
6. Standard passivation and metallisation

The key difference to PERC: the tunnel oxide/poly-Si structure on the rear side dramatically reduces surface recombination.

Applications: Residential buildings, commercial, large-scale systems. TOPCon will replace PERC as the standard technology.

Manufacturer examples: LONGi (Hi-MO 7), Jinko Solar (Tiger Neo), JA Solar (DeepBlue 4.0), Trina Solar (Vertex S+)

Heterojunction (HJT)

HJT (Heterojunction Technology) combines crystalline and amorphous silicon in a single cell, achieving exceptional properties.

Manufacturing process:

1. n-type wafer production and cleaning
2. Double-sided deposition of amorphous silicon (a-Si:H):
   • Intrinsic layer (i) as passivation (~5 nm)
   • Doped layer (p or n) as emitter/BSF (~10 nm)
3. Transparent conductive oxides (ITO) on both sides
4. Low-temperature process (less than 200 degrees C, versus more than 800 degrees C for PERC/TOPCon)
5. Copper or silver metallisation

Applications: Premium roof systems, agri-PV (bifacial), large-scale systems in hot climates.

Manufacturer examples: Meyer Burger (Made in Germany), REC (Alpha Pure R), Huasun, Maxwell

Polycrystalline

Polycrystalline (or multicrystalline) cells consist of many small silicon crystals rather than a single crystal.

Manufacturing process:

1. Block casting: silicon is poured into a mould and cooled in a controlled manner
2. Solidification forms many crystallites (visible as a “frost pattern”)
3. Further steps similar to PERC, but with simpler passivation

Applications: Large-scale ground-mounted systems in developing countries, remaining stock.

Manufacturer examples: Hardly any relevant manufacturers in the DACH market; occasionally in the Asian market.

Thin-Film Technologies

Thin-film modules consist of thin semiconductor layers (a few micrometres) deposited on a substrate. They require significantly less material than crystalline cells.

CdTe (Cadmium Telluride)

CdTe is the most successful thin-film technology and is manufactured almost exclusively by First Solar.

Manufacturing process:

1. Superstrate configuration: glass substrate as light entry surface
2. Sputtering of the TCO front contact (SnO2:F)
3. Chemical bath deposition of the CdS buffer layer
4. Thermal evaporation of the CdTe absorber layer (~3-5 um)
5. CdCl2 activation (improves grain boundary properties)
6. Rear contact deposition

Applications: Large ground-mounted systems, solar parks worldwide.

Manufacturer: First Solar (Series 7, CdTe)

CIGS (Copper Indium Gallium Selenide)

CIGS (Cu(In,Ga)Se2) is the most versatile thin-film technology with the highest lab efficiency among thin-film materials.

Applications: Building integration (facades, roof tiles), special applications.

Manufacturer examples: Manz AG, Solibro, Avancis

Emerging Technologies

Perovskite Solar Cells

Perovskite solar cells are considered the most promising new development in PV research. The name refers to the crystal structure ABX3 (e.g. methylammonium lead iodide, CH3NH3PbI3).

Manufacturing process:

1. Solution-based deposition (low-cost, low temperatures)
2. Alternatively: vacuum evaporation for more homogeneous layers
3. Active layer thickness only ~300-500 nm
4. Entire cell can be manufactured in a few hours

Perovskite/Silicon Tandem

Tandem cells combine two different semiconductor materials to utilise a broader portion of the solar spectrum. The most promising combination: Perovskite (top cell) absorbs short-wavelength light, Silicon (bottom cell) absorbs the long-wavelength remainder.

Why tandem is so promising:

Perovskite/Si Tandem43 %

Triple-Junction49 %

c-Si (Single Junction)29,4 %

CdTe (Single Junction)32 %

Perovskite (Single)33 %

Shockley-Queisser limits for various configurations

Research institutions: Helmholtz-Zentrum Berlin (HZB), Oxford PV, Fraunhofer ISE, EPFL, LONGi

Efficiency Development Comparison

Pero/Si Tandem33,9 %

c-Si IBC26,7 %

c-Si HJT26,8 %

TOPCon26,4 %

Perovskite26,1 %

PERC24,1 %

CIGS23,6 %

Poly-Si23,3 %

CdTe22,1 %

Lab records | Source: NREL Best Research-Cell Efficiencies Chart, as of Jan. 2026

Applications by Technology

Application	Recommended technology	Rationale
Single-family home (standard)	TOPCon or PERC	Best price-performance ratio
Single-family home (premium)	HJT or IBC	Maximum yield, best warranties
Flat roof (bifacial)	HJT	Symmetrical structure, lowest temp. coefficient
Large solar park	CdTe or TOPCon	Lowest $/Wp or best yield
Agri-PV	HJT (bifacial)	Light transmission, rear-side yield
Building facade (BIPV)	CIGS or thin-film	Flexible formats, aesthetic
Balcony power station	PERC or TOPCon	Compact, proven, affordable
Motorhome/Camper	PERC (flexible)	Lightweight, flexible, affordable

Future Outlook

Short-term (2026-2027)

• TOPCon replaces PERC as standard (more than 50% market share expected)
• HJT grows in the premium segment to 8-10% market share
• PERC remains available, but prices continue to fall
• First perovskite modules in pilot projects

Medium-term (2028-2030)

• Perovskite/Si tandem reaches mass production (more than 30% efficiency)
• IBC is displaced by TOPCon/HJT hybrid designs
• Polycrystalline almost completely disappears
• New metallisation processes reduce silver consumption

Long-term (2030+)

• Multi-junction tandem cells with more than 35% efficiency
• Lead-free perovskites (tin-based) solve the toxicity problem
• Flexible, printable solar cells for new application fields
• Integration into windows, vehicles, textiles

Manufacturer Overview 2026

Premium Segment

Manufacturer	Technology	Top product	Module eff.	Feature
Maxeon	IBC	Maxeon 7	23.0%	40-year warranty
Meyer Burger	HJT	White HJT	22.0%	Made in Germany
REC	HJT	Alpha Pure R	22.3%	Lead-free cells
SunPower	IBC/HJT	Performance 7	22.8%	All-black design

Mainstream Segment

Manufacturer	Technology	Top product	Module eff.	Feature
LONGi	TOPCon	Hi-MO 7	22.5%	World’s largest manufacturer
Jinko Solar	TOPCon	Tiger Neo	22.3%	Module market leader
JA Solar	TOPCon	DeepBlue 4.0	22.0%	Value for money
Trina Solar	TOPCon	Vertex S+	22.2%	Compact format
Canadian Solar	TOPCon	TOPBiHiKu7	21.8%	Bifacial

Thin-Film

Manufacturer	Technology	Top product	Module eff.	Feature
First Solar	CdTe	Series 7	18.5%	Only major CdTe manufacturer
Avancis	CIGS	PowerMax	16.5%	BIPV specialist

Frequently Asked Questions about Module Technologies

What is the difference between monocrystalline and polycrystalline?

Monocrystalline: Consists of a single silicon crystal. The uniform crystal structure enables higher efficiencies (19-23%). Recognisable by the uniformly dark surface.

Polycrystalline: Consists of many small crystals. The grain boundaries between crystals cause recombination losses and reduce efficiency to 15-17%. Recognisable by the bluish “frost” pattern.

In 2026, there are hardly any reasons to choose polycrystalline — the price difference to monocrystalline has become minimal.

What do PERC, TOPCon and HJT mean?

• PERC (Passivated Emitter and Rear Cell): Rear-side passivation with Al2O3 reduces recombination. Standard since 2019.
• TOPCon (Tunnel Oxide Passivated Contact): Ultra-thin tunnel oxide + poly-Si on the rear side. Even better passivation than PERC. The new standard.
• HJT (Heterojunction Technology): Combination of crystalline and amorphous silicon. Best temperature coefficient, but more expensive.

All three are based on monocrystalline silicon but differ in cell design and passivation strategy.

Is investing in more expensive technology worthwhile?

It depends on your situation:

• Limited roof area: Yes — higher efficiency = more kWp on the same area
• Hot location: Yes — low temperature coefficient (HJT) delivers 3-5% more annual yield
• Large area available: Probably not — cheaper modules with more area are more economical
• 30+ year use planned: Yes — better modules degrade more slowly

Calculate the additional yield over 25 years with our PV calculator.

When will perovskite modules come to market?

Realistic timeline:

• 2026-2027: First pilot installations (Oxford PV, CubicPV)
• 2028-2029: Limited commercial availability (as tandem)
• 2030+: Broader market penetration

The main problem remains long-term stability: perovskites degrade under real conditions significantly faster than silicon. Until reliable 25-year warranties are possible, silicon remains the safe choice.

Are thin-film modules suitable for my house roof?

Generally no for standard house roofs:

• CdTe modules (First Solar) are designed for large-scale systems
• CIGS modules are rare and more expensive per kWp
• The lower efficiency requires more area

Thin-film makes sense for:

• Building integration (facade, roof tiles)
• Curved or irregular surfaces
• Aesthetic requirements (uniform appearance)

What is bifacial technology?

Bifacial modules use light from both sides — both direct sunlight from the front and reflected light from the rear. The additional yield is typically 5-25%, depending on:

• Albedo of the substrate (white roofs, snow: up to 25%)
• Mounting height (higher = more rear-side irradiation)
• Module spacing

HJT cells are ideal for bifacial modules due to their symmetrical structure. TOPCon modules are also suitable for bifacial use.

Conclusion

The choice of the right module technology depends on your individual requirements. For most applications in the DACH region in 2026:

1. TOPCon as the new standard technology — best balance of efficiency, price and future-proofing
2. PERC remains a solid choice for budget-conscious projects
3. HJT for premium requirements and special applications (flat roof, hot climates)
4. Thin-film only for large-scale systems or BIPV
5. Perovskite/Tandem is the future — but not yet ready for investment

Compare modules and calculate your individual yield with our PV calculator.

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Further reading:

• Solar cell efficiency comparison 2026
• How does photovoltaics work? — The physics explained
• History of photovoltaics
• The right inverter for your system