# How the First Practical Silicon Solar Cell Works > A 1954 invention by Bell Labs researchers that created the first silicon-based solar cell capable of converting sunlight into enough electricity to power everyday devices. - **Patent:** US 2780765 - **Original title:** Solar energy converting apparatus - **Owner:** Bell Telephone Laboratories Inc - **Granted:** 1957 - **Status:** Public domain (expired) - **Times cited:** 59 - **Field:** energy, semiconductors, consumer_electronics ## What it does This patent describes a device that uses a silicon body to turn sunlight into electrical current to charge a battery. It creates a p-n junction by placing a thin p-type zone, doped with boron, next to an n-type zone. The p-type zone is kept thin—specifically, about the same thickness as the distance electrons can travel before recombining—to ensure electricity is generated efficiently. It also includes a one-way electrical gate, known as a unilaterally-conductive element, to ensure power flows from the solar cell to the battery but prevents the battery from draining back through the cell at night. ## What it does NOT cover - Does not cover solar cells made from materials other than silicon. - Does not cover solar power systems that lack a battery for energy storage. - Does not cover the use of non-boron impurities for creating the p-type zone. - Does not cover solar cells without the specific one-way electrical gate (diode) for preventing battery discharge. ## The clever bit The inventors realized that by carefully controlling the thickness of the p-type layer to match the electron diffusion length, they could maximize the number of electrons collected before they were lost, drastically increasing efficiency. ## Real-world examples 1. Early space satellite power systems 2. Modern silicon-based rooftop solar panels 3. Solar-powered calculators 4. Off-grid remote power stations ## Why it matters This is the foundational patent for modern photovoltaics. Before this, solar cells were made of selenium and were far too inefficient for practical use. This invention proved that silicon could generate enough power to run electronics, eventually leading to the global solar energy industry. ## Frequently asked questions ### What does How the First Practical Silicon Solar Cell Works cover? A 1954 invention by Bell Labs researchers that created the first silicon-based solar cell capable of converting sunlight into enough electricity to power everyday devices. ### Who owns patent US 2780765? Bell Telephone Laboratories Inc owns this patent, granted in 1957. ### When does this patent expire? This patent has expired and is now in the public domain — anyone can use the invention freely. ### What is patent US 2780765 cited by? This patent has been cited by 59 later patents that build on its ideas. ### What problem does this patent solve? This is the foundational patent for modern photovoltaics. Before this, solar cells were made of selenium and were far too inefficient for practical use. This invention proved that silicon could generate enough power to run electronics, eventually leading to the global solar energy industry. ### What does this patent NOT cover? Does not cover solar cells made from materials other than silicon. **Full plain-English explainer:** https://patentbrief.org/patent/us/2780765/solar-cell-photovoltaic **Original patent:** https://patents.google.com/patent/US2780765 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How Amorphous Silicon Changed Solar Power](https://patentbrief.org/patent/us/4064521/semiconductor-device-having-a-body-of-amorphous-silicon) — This 1976 patent describes using a specific form of non-crystalline silicon to create cheap, thin semiconductor devices like solar cells. - [The Invention of the Junction Transistor](https://patentbrief.org/patent/us/2569347/junction-transistor) — William Shockley's 1951 patent for the junction transistor, the fundamental building block of all modern digital electronics. - [The Invention of the Modern Field-Effect Transistor](https://patentbrief.org/patent/us/3102230/mosfet-field-effect-transistor) — This 1960 patent describes the fundamental structure of the MOSFET, the tiny electronic switch that powers every modern computer processor. - [The Invention of the Transistor](https://patentbrief.org/patent/us/2524035/point-contact-transistor) — Bell Labs' 1950 patent for the point-contact transistor, the fundamental electronic component that makes all modern computing possible. - [How the First Infrared LED Was Invented](https://patentbrief.org/patent/us/3293513/infrared-led-biard-pittman) — Texas Instruments' 1962 patent for the first practical semiconductor diode that emits infrared light when electricity passes through it.