Solar photovoltaics: Techniques
Why silicon won, and where perovskite tandems fit
What this tab covers The methods used to capture this energy: how each works, and how they compare on efficiency, cost, life-cycle emissions, maturity and scale.About 98% of modules made today are crystalline silicon; thin films are a niche and tandems are at pilot stage.
Comparison
| Method | Efficiency | Cost | Life-cycle emissions | Maturity | Scale |
|---|---|---|---|---|---|
| Crystalline silicon cells (including TOPCon and heterojunction)13 | 22.7% average module | About USD 0.10 per watt for modules (2025) | Harmonised median 45 g CO2e/kWh (1,700 kWh/m2 a year, 30-year life) | mature | About 690 GWp of the 706 GWp made in 2025 |
| Thin-film cells (CdTe, CIGS)14 | CdTe modules almost 20% | No separate price in the sources used | Harmonised 14 (CdTe) and 26 (CIGS) g CO2e/kWh at a sunnier 2,400 kWh/m2 a year | mature (niche) | About 16 GWp in 2025 |
| Perovskite and perovskite-silicon tandem cells161920 | Cell records 35.2-35.5% | No commercial price yet | Prospective estimate 8-10 g CO2e/kWh by 2050, against 11-13 for silicon | pilot | Not yet in mass production |
| Utility-scale, rooftop, floating, agrivoltaic and building-integrated PV21521 | Capacity factor 16% (utility, 2025) | Utility LCOE USD 44/MWh and USD 667/kW (2025), 89% below 2010 | 23-82 g CO2e/kWh depending on where panels are made | mature (ground, rooftop); early commercial (others) | About 510 GW of solar PV added in 2025; about 2,391 GW of solar capacity (PV and CSP) installed at end-2025 (IRENA) |
| Concentrator PV1 | Modules up to 38.9% | No current market price | No harmonised figure | niche | No market figures reported |
Silicon dominates because module prices fall about 26.6% with each doubling of cumulative production. Thin films' lower harmonised footprints assume sunnier sites, so the real gap is smaller. Tandems and concentrators win on efficiency but not yet on cost or durability. A European system repays its manufacturing energy in about 0.9-1.1 years.
How each method works
Crystalline silicon cells (including TOPCon and heterojunction)Purified silicon is grown into crystals, sliced into wafers and doped so that an internal electric field forms. Light frees electrons, which the field drives out through silver contacts as current.13
Thin-film cells (CdTe, CIGS)A semiconductor layer a few micrometres thick is deposited directly on glass; it absorbs light far more strongly than silicon, so little material is needed.14
Perovskite and perovskite-silicon tandem cellsPerovskites are lead-halide crystals coated at low temperature. On top of silicon they capture blue light while silicon takes red, wasting less energy as heat.161920
Utility-scale, rooftop, floating, agrivoltaic and building-integrated PVModules are mounted on steel frames or sun-tracking rows, roofs, pontoons, raised frames over crops, or built into facades. Inverters convert direct to alternating current.21521
Concentrator PVLenses focus direct sunlight onto tiny multi-junction cells on two-axis trackers; output collapses in cloud or haze.1
Sources
- Photovoltaics Report (updated 14 July 2026) Fraunhofer Institute for Solar Energy Systems ISE, 2026
- Renewable Power Generation Costs in 2025 (Executive summary, Figure S1) IRENA, 2026
- Life Cycle Greenhouse Gas Emissions of Crystalline Silicon Photovoltaic Electricity Generation: Systematic Review and Harmonization (Hsu et al., Journal of Industrial Ecology 16 S1) NREL LCA Harmonization Project / RePEc, 2012
- Life Cycle Greenhouse Gas Emissions of Thin-film Photovoltaic Electricity Generation: Systematic Review and Harmonization (Kim et al., Journal of Industrial Ecology 16 S1) NREL LCA Harmonization Project / RePEc, 2012
- What are the safest and cleanest sources of energy? (life-cycle range from UNECE) Our World in Data, 2024
- Best Research-Cell Efficiency Chart (Rev. 17 July 2026) National Laboratory of the Rockies (formerly NREL), 2026
- LONGi Breaks World Record to 35.5% for Crystalline Silicon-Perovskite Tandem Solar Cell Efficiency (press release; certified by ESTI) LONGi, 2026
- Comparing Environmental Impacts of Single-Junction Silicon and Silicon/Perovskite Tandem Photovoltaics: A Prospective Life Cycle Assessment (van der Hulst et al., ACS Sustainable Chemistry and Engineering 12(23), 8860-8870) American Chemical Society, 2024
- Renewable Capacity Statistics 2026 (as reported: IRENA: World adds 510GW of new solar PV capacity in 2025) IRENA via PV Tech, 2026