Fix dollar signs + add descendants section

# [TECH] Solar Cells (Photovoltaics)

**Solar Cells** convert sunlight directly into electricity via the photovoltaic effect, and have become the cheapest source of electricity in history as of 2020.

## Overview

Becquerel discovered the photovoltaic effect (1839). Bell Labs produced the first practical silicon solar cell (1954, Chapin, Fuller, Pearson; 6% efficiency). Space programme demand drove early production. The key breakthrough was cost reduction via silicon wafer manufacturing borrowed from the semiconductor industry. By 2023, global installed capacity exceeded 1,400 GW; levelised cost of solar electricity fell from >\$80/W (1980) to <\$0.30/W (2023), a 99.6% reduction — the steepest cost decline of any energy technology.

## Key Actors

- **Companies**: Bell Labs/AT&T (1954), ARCO Solar (1977), First Solar (1999), SunPower (1985), LONGi (2000), BYD, CATL
- **Inventors**: Daryl Chapin (1906–1995), Calvin Fuller (1902–1994), Gerald Pearson (1905–1987)

## Key Patents

- Chapin, D.M., Fuller, C.S. & Pearson, G.L. US Patent 2,780,765 (1957) — silicon solar cell

## Economic Value

Global PV market: **\$270 billion/year** installed capacity (BloombergNEF 2023). Generating ~3,000 TWh/year of electricity. Expected to grow to \$1.5T+/year by 2030. Carbon avoidance value at \$50/tonne CO₂: additional ~\$150B/year.

## Notes

BloombergNEF *New Energy Outlook* 2023 for cost and capacity data. IRENA *Renewable Power Generation Costs* 2023 for levelised cost trajectory.

## What This Enables
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- **[TECH] Electric Vehicles (EVs)** — Solar electricity reduces the lifecycle carbon footprint of EVs and powers home charging stations.
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# Parents

* [SCI] Semiconductor Physics
* [TECH] Chemical Industry
* [SCI] Semiconductor Physics
* [SCI] Climate Science