Physics / mechanism
Photovoltaic conversion exploits the photoelectric effect in semiconductor p-n junctions. Incident photons with energy ≥ bandgap excite electron-hole pairs; built-in junction field separates carriers before recombination, driving current. Key parameters: bandgap (eV), minority carrier lifetime, contact resistance, reflection losses. Efficiency ceiling set by Shockley-Queisser limit (~33% single-junction). Commercial monocrystalline silicon sits at 22–24% (PERC/TOPCon); perovskite-silicon tandems have hit 33.9% in lab. III-V multijunction (GaAs, InGaP) reaches 47% under concentration but costs orders of magnitude more. Thin-film (CdTe, CIGS) trades efficiency (18–23%) for lower $/W manufacturing.
Competitive landscape
Silicon dominates on cost (sub-$0.15/W module). Competition comes from perovskite (stability + scalability unresolved), CIGS (niche flexibility/BIPV), III-V (space, CPV), and organic PV (ultra-low cost, very low efficiency). Adjacent: thermal solar (CSP), solid-state lighting (inverse photonics), photodetectors sharing the same junction physics.
| Technology | Efficiency | Cost driver |
|---|---|---|
| c-Si TOPCon | 22–24% | Scale, mature supply chain |
| Perovskite-Si tandem | 28–34% | Encapsulation, Pb regulation |
| III-V multijunction | 38–47% | Epitaxial growth cost |
Companies using
Connected ideas
Sources
Frontier (open questions)
- To be added.