History of Photovoltaics: From Becquerel to the Terawatt Era
The history of solar cells from 1839 to today: milestones, efficiency records, price trends and the key figures of photovoltaics.
History of Photovoltaics
Converting sunlight into electrical current is one of humanity’s most significant technological achievements. What began in 1839 with a chance observation in a Parisian laboratory is today the world’s fastest-growing energy source. This article traces the fascinating development of photovoltaics — from the first physical principles to the terawatt era.
Interactive Timeline
Explore the key milestones in photovoltaic history. Filter by category to focus on discoveries, technological breakthroughs, industrial milestones, policy decisions or efficiency records.
Entdeckung des photoelektrischen Effekts
EntdeckungDer französische Physiker Alexandre Edmond Becquerel entdeckt im Alter von nur 19 Jahren den photoelektrischen Effekt, als er beobachtet, dass bestimmte Materialien bei Lichteinfall elektrische Spannung erzeugen.
Photoleitfähigkeit von Selen
EntdeckungWilloughby Smith entdeckt die Photoleitfähigkeit von Selen – die elektrische Leitfähigkeit des Elements ändert sich bei Lichteinfall. Dies legt den Grundstein für die erste Solarzelle.
Erste Solarzelle aus Selen
TechnologieCharles Fritts baut die erste funktionsfähige Solarzelle aus einer Selen-Schicht mit dünner Goldbeschichtung. Der Wirkungsgrad beträgt nur etwa 1 %, doch das Prinzip ist bewiesen.
Einstein erklärt den Photoeffekt
EntdeckungAlbert Einstein veröffentlicht seine Arbeit zur Lichtquantenhypothese und erklärt den photoelektrischen Effekt. Dafür erhält er 1921 den Nobelpreis für Physik.
Czochralski-Verfahren
TechnologieJan Czochralski entwickelt ein Verfahren zur Herstellung von Einkristallen. Das Czochralski-Verfahren wird später zur Grundlage der Produktion von monokristallinem Silizium für Solarzellen.
Erste praktische Silizium-Solarzelle
TechnologieDaryl Chapin, Calvin Fuller und Gerald Pearson bei den Bell Laboratories entwickeln die erste praktisch nutzbare Silizium-Solarzelle mit einem Wirkungsgrad von etwa 6 %. Die New York Times nennt es "den Beginn einer neuen Ära".
Vanguard 1 – erster Solar-Satellit
IndustrieDer US-Satellit Vanguard 1 nutzt als erstes Raumfahrzeug Solarzellen zur Energieversorgung. Die Zellen liefern jahrelang zuverlässig Strom und beweisen die Langlebigkeit der Technologie.
Shockley-Queisser-Limit
EntdeckungWilliam Shockley und Hans-Joachim Queisser berechnen den theoretisch maximalen Wirkungsgrad einer Einfach-Solarzelle: etwa 33,7 % für Silizium. Dieses Limit gilt bis heute als fundamentale Grenze.
Ölkrise als Katalysator
PolitikDie erste Ölkrise löst weltweit eine Suche nach alternativen Energiequellen aus. Die Forschungsbudgets für Solarenergie steigen deutlich, besonders in den USA und Japan.
Amorphes Silizium (Dünnschicht)
TechnologieDavid Carlson und Christopher Wronski entwickeln die erste Solarzelle aus amorphem Silizium. Dünnschichtzellen ermöglichen günstigere Produktion, allerdings bei niedrigerem Wirkungsgrad.
20 % Wirkungsgrad erreicht
RekordDie University of New South Wales (UNSW) unter Martin Green erreicht erstmals einen Wirkungsgrad von über 20 % mit einer monokristallinen Silizium-Solarzelle im Labor.
Deutsches 1.000-Dächer-Programm
PolitikDeutschland startet das 1.000-Dächer-Programm – eine der ersten großen staatlichen Förderinitiativen für private PV-Anlagen auf Dächern. Es werden über 2.000 Anlagen installiert.
Erneuerbare-Energien-Gesetz (EEG)
PolitikDas deutsche Erneuerbare-Energien-Gesetz tritt in Kraft und garantiert feste Einspeisevergütungen für Solarstrom über 20 Jahre. Das EEG wird zum internationalen Vorbild und löst einen Solarboom aus.
Deutschland wird PV-Weltmeister
IndustrieDeutschland überholt Japan und wird zum weltweit größten Markt für Photovoltaik. Die installierte Leistung wächst rasant von 400 MWp (2003) auf über 1 GWp.
Grid Parity in Sicht
IndustrieDie Kosten für PV-Strom sinken unter 0,25 €/kWh. Erstmals wird Grid Parity – die Kostengleichheit mit konventionellem Netzstrom – für sonnige Regionen prognostiziert.
PV-Kosten unter 1 $/Wp
IndustrieDer Modulpreis fällt erstmals unter 1 US-Dollar pro Watt peak (Wp). Chinesische Hersteller dominieren den Weltmarkt. Die Preise sind seit 2006 um über 70 % gefallen.
PERC-Zellen in Massenproduktion
TechnologieDie PERC-Technologie (Passivated Emitter and Rear Cell), ursprünglich in den 1980ern erfunden, geht in die Massenproduktion. PERC erhöht den Wirkungsgrad um 1–2 Prozentpunkte und wird zum neuen Standard.
Solar günstigste Energiequelle
IndustrieIn vielen sonnigen Regionen wird Photovoltaik zur günstigsten Form der Stromerzeugung überhaupt. Auktionspreise in Chile und den VAE fallen unter 3 US-Cent/kWh.
Perowskit-Tandem über 29 %
RekordDas Helmholtz-Zentrum Berlin erreicht mit einer Perowskit-Silizium-Tandemzelle einen Rekordwirkungsgrad von 29,15 %. Tandemzellen gelten als vielversprechendste Technologie für die nächste Generation.
TOPCon löst PERC ab
TechnologieTOPCon-Zellen (Tunnel Oxide Passivated Contact) beginnen PERC als dominante Technologie abzulösen. Große Hersteller wie LONGi und JA Solar stellen ihre Produktion um.
0 % MwSt auf PV in Deutschland
PolitikDeutschland führt den Nullsteuersatz (0 % Mehrwertsteuer) für private PV-Anlagen bis 30 kWp ein. Die Anschaffungskosten sinken deutlich. Ein Rekordjahr mit über 14 GWp Zubau.
Perowskit-Tandem über 33 %
RekordLONGi erzielt mit einer Perowskit-Silizium-Tandemzelle einen Rekordwirkungsgrad von 33,9 % im Labor. Erste kommerzielle Tandemmodule kündigen sich an.
HJT und TOPCon im Massenmarkt
IndustrieHeterojunction-Zellen (HJT) und TOPCon dominieren den Premium-Markt. Die durchschnittliche Moduleffizienz überschreitet 22 %. Weltweit sind über 2 TW (Terawatt) PV installiert.
Energy Sharing und 800W Balkonkraftwerke
PolitikDeutschland ermöglicht Energy Sharing ab Juli 2026. Die 800W-Einspeisegrenze für Balkonkraftwerke (mit bis zu 2.000 Wp Modulleistung) macht Solarenergie auch für Mieter zugänglich.
The Beginnings: 1839-1953
The Photoelectric Effect
The history of photovoltaics begins in 1839 in Paris. The then 19-year-old Alexandre Edmond Becquerel was experimenting with electrolytic cells and noticed that an electrical voltage arose when exposed to light. He had discovered the photoelectric effect — without realising its significance.
Decades later, in 1873, Willoughby Smith found that selenium changes its electrical conductivity under the influence of light. Building on this, Charles Fritts constructed the first solar cell in 1883: a gold-coated selenium disc with an efficiency of about 1%.
Einstein and Light Quanta
In 1905, Albert Einstein provided the theoretical explanation for the photoelectric effect: light consists of energy packets (photons) that can release electrons when they strike a material. This insight, for which Einstein received the Nobel Prize in 1921, was fundamental to understanding photovoltaics.
In 1918, Jan Czochralski developed a method for producing single crystals. The process named after him is still used today to grow high-purity monocrystalline silicon for solar cells.
The Breakthrough: 1954 — Bell Labs
On 25 April 1954, Daryl Chapin, Calvin Fuller and Gerald Pearson at Bell Laboratories presented the first practically usable silicon solar cell. With an efficiency of about 6%, it was six times more efficient than all previous solar cells.
The New York Times wrote on page 1: “The use of solar energy has thus come closer to the beginning of a new era.”
The Space Age: 1958-1972
The first commercial customers for solar cells were not homeowners, but space agencies. In 1958, the US satellite Vanguard 1 launched with solar cells for power supply. The cells provided power reliably for years — far longer than the chemical batteries on board.
In the following decades, solar cells became the standard power supply for satellites and space stations. The extreme requirements of space exploration drove technological development:
- Higher efficiency to reduce weight
- Radiation resistance against cosmic radiation
- Long-term stability over many years
Theoretical Limits: The Shockley-Queisser Limit
In 1961, William Shockley and Hans-Joachim Queisser calculated the theoretically maximum efficiency of a single-junction solar cell: approximately 33.7% for silicon. Photons with too little energy cannot excite an electron (transmission loss), while excess energy is lost as heat (thermalisation loss).
This fundamental limit shows why multi-junction and tandem cells are so promising: by combining multiple semiconductor materials, a broader spectrum can be utilised and the limit exceeded.
Oil Crisis and Terrestrial Use: 1970s
The oil crisis of 1973 changed energy policy worldwide. Suddenly, the search for alternative energy sources became a strategic priority. Research budgets for solar energy increased dramatically.
In 1976, David Carlson and Christopher Wronski developed the first solar cell from amorphous silicon (thin-film). This technology enabled significantly cheaper manufacturing processes, as less high-purity silicon was needed.
The Efficiency Revolution
The development of solar cell efficiency is one of the most impressive technological progress curves in history:
Quellen: NREL Best Research-Cell Efficiency Chart, Fraunhofer ISE
Key Efficiency Milestones
- 1985: Martin Green at UNSW achieves 20% for the first time with a monocrystalline silicon cell
- 1994: The PERL cell (Passivated Emitter, Rear Locally-diffused) reaches 24%
- 2014: PERC cells (Passivated Emitter and Rear Cell) enter mass production at 20-22%
- 2020: Perovskite-silicon tandem reaches 29.15% (Helmholtz-Zentrum Berlin)
- 2024: LONGi achieves 33.9% with perovskite tandem — the Shockley-Queisser limit is surpassed
The Price Revolution
Even more dramatic than the efficiency gains is the price decline of solar modules. Since the 1970s, costs have fallen by over 99.8%:
Quellen: Fraunhofer ISE, IRENA, Our World in Data. Preise in USD (2024) pro Watt Peak.
Swanson’s Law
Similar to Moore’s Law for computer chips, photovoltaics has Swanson’s Law: with each doubling of cumulative production volume, the price falls by approximately 20-24%. This learning curve effect has remained stable over four decades.
The reasons for the price decline:
- Economies of scale through mass production (especially in China)
- Technological improvements (thinner wafers, higher efficiency)
- Material efficiency (less silicon per watt)
- Automation of manufacturing processes
- Competition between manufacturers
Policy Milestones
The Renewable Energy Act (EEG)
The year 2000 marks a turning point. The German Renewable Energy Act (EEG) guaranteed fixed feed-in tariffs for 20 years, creating the investment security needed for expansion. The EEG was copied worldwide and is considered one of the most important drivers of the global solar revolution.
Further Policy Milestones
- 1991: German 1,000 Roofs Programme — first large-scale residential PV subsidy
- 2004: Germany becomes the world’s PV leader (over 1 GWp installed)
- 2023: 0% VAT on private PV systems in Germany
- 2026: Energy sharing and 800W balcony power station regulation in Germany
Current Technologies: TOPCon, HJT and Perovskite
Photovoltaics continues to develop rapidly. The most important current technology trends:
| Technology | Efficiency (commercial) | Status | Feature |
|---|---|---|---|
| PERC | 20-22% | Phasing out | Previous standard since 2014 |
| TOPCon | 22-25% | New standard | Better passivation |
| HJT | 22-25% | Premium market | Lowest temperature coefficient |
| Perovskite tandem | more than 29% (lab) | Research/pilot production | Potentially cheap manufacturing |
Learn more about individual technologies in the article on module types and efficiency.
Outlook: The Terawatt Era
In 2025, globally installed PV capacity exceeded 2 terawatts for the first time — 2,000 gigawatts. For comparison: in the year 2000, it was just 1.5 GW. The International Energy Agency (IEA) forecasts over 5 TW of installed capacity by 2030.
The coming years will be shaped by:
- Perovskite tandem cells in commercial production
- Agri-PV (combining agriculture and solar energy)
- Building-integrated PV (BIPV) as facade and roof elements
- Floating solar systems on water bodies
- Energy sharing and decentralised energy communities
Frequently Asked Questions
Who invented the solar cell?
The first functional solar cell was built in 1883 by Charles Fritts from selenium. The first practically usable silicon solar cell was developed in 1954 by Chapin, Fuller and Pearson at Bell Laboratories. The underlying photoelectric effect was discovered by Becquerel as early as 1839.
Why did Germany become the world’s PV leader?
The Renewable Energy Act (EEG) of 2000 guaranteed fixed feed-in tariffs for 20 years, creating unique investment security. Combined with the 100,000 Roofs Programme and falling module prices, this triggered an unprecedented PV boom.
How much have solar module prices fallen?
Since 1976, module prices have dropped from approx. 76 USD/Wp to under 0.15 USD/Wp — a decline of over 99.8%. This phenomenon is described by Swanson’s Law: with each doubling of production capacity, the price falls by 20-24%.
What is the Shockley-Queisser limit?
The theoretical maximum efficiency of a single-junction silicon solar cell, calculated in 1961: approx. 33.7%. It limits how much of the incident sunlight can be converted into electricity. Tandem cells with multiple semiconductor layers can exceed this limit.
What role did space exploration play in photovoltaic development?
Space exploration was the first major driver of photovoltaics: from 1958, satellites like Vanguard 1 used solar cells as their sole power source. NASA invested heavily in efficiency improvements, which laid the foundation for later terrestrial applications.
Sources: NREL Best Research-Cell Efficiency Chart, Fraunhofer ISE Photovoltaics Report, IRENA Renewable Cost Database, IEA World Energy Outlook, Our World in Data
Table of Contents
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