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.
Original patent title: “Solar energy converting apparatus”
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. Granted to Bell Telephone Laboratories Inc in 1957 with 2 claims and 59 forward citations, and it is now in the public domain.
Coverage
What does this patent actually cover?
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.
The gap
What does this patent 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.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
Key facts
What made this novel
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.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Early space satellite power systems
Modern silicon-based rooftop solar panels
Solar-powered calculators
Off-grid remote power stations
Why it matters
The bigger picture
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.
Filed
March 5, 1954
Granted
February 5, 1957
Market context
Who's building on this
Companies in this space
Companies like First Solar, SunPower, and JinkoSolar continue to refine the p-n junction physics established here. While the original Bell Labs patent has long expired, the fundamental architecture of the silicon solar cell remains the industry standard.
Market impact
This patent triggered the transition from theoretical solar research to a viable commercial power source. It enabled the space race by providing a reliable power source for satellites and laid the groundwork for the multi-billion dollar renewable energy market we see today.
Claim 1 — Plain English
What this patent covers
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.
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.
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.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
Patent enters public domain
This patent is in the public domain
See the Freedom to Build guide — what is free to use, what is not, and how to cite this patent.
PatentBrief Score
Impact Score
Early stage
Citation count
35/40
Highly cited
Claim breadth
1/20
Narrow claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$30K – $97K
Midpoint $60K · expired or expiring · industry ×1.4
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Patent Claims
1 independent claim · 0 dependent
Claims are the legal boundaries of the patent. An independent claim stands alone. A dependent claim adds limitations to its parent, narrowing — but not broadening — the scope.
The original legal language
Original claims
2 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Pearson, G. L., Fuller, C. S., & Chapin, D. M. (1957). How the First Practical Silicon Solar Cell Works (U.S. Patent No. 2,780,765). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/2780765/solar-cell-photovoltaic
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
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.
Same assignee
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