Technology and the built world

SolFocus (company)

SolFocus, Inc. was a concentrating photovoltaic startup founded in 2006 and based in Mountain View, California, which deployed about 18 megawatts of solar projects before winding up in 2013.

SOLID is a mnemonic acronym for five object-oriented design principles: Single Responsibility, Open/Closed, Liskov Substitution, Interface Segregation, and Dependency Inversion, assembled by Robert C. Martin in the 1990s and 2000s.

Solid electrolyte

A solid-state electrolyte is a solid material, typically a ceramic, glass-ceramic, polymer, or composite, that conducts lithium, sodium, or potassium ions between a battery's electrodes while suppressing electronic conduction.

Solid electrolyte interphase

The solid electrolyte interphase (SEI) is a nanoscale passivation layer on lithium batteries' negative electrode that conducts ions but blocks electrons, forming mainly during the first charge.

Solid electrolyte interphase engineering

Solid electrolyte interphase (SEI) engineering is the deliberate design of the film that forms on a battery anode from electrolyte decomposition, aiming for stable, lithium-metal cells.

Solid electrolyte reactor for CO2 electrolysis

A solid electrolyte reactor for CO2 electrolysis is an electrochemical cell that uses a solid electrolyte to produce pure, concentrated chemicals like formic acid directly from CO2.

Solid oxide electrolysis cell

A solid oxide electrolysis cell (SOEC) is an electrochemical device that splits steam, and optionally carbon dioxide, into hydrogen at high temperature, reaching efficiencies up to 84%.

Solid oxide fuel cell

A solid oxide fuel cell (SOFC) is an electrochemical device that converts fuels like hydrogen or natural gas directly into electricity using a hot ceramic electrolyte.

Solid particle thermal storage

Solid particle thermal storage heats sand-like ceramic or silica particles above 1000 °C and holds them until the heat drives a power cycle or supplies industrial heat.

Sep 29, 2026

Solid phase crystallization

Solid phase crystallization (SPC) is a simple, low-cost thin-fabrication method that anneals amorphous semiconductor films into polycrystalline silicon for thin-film transistors, though furnace processing takes hours.

Solid polymer electrolyte battery

A solid polymer electrolyte battery is a rechargeable battery in which a solid polymer-salt complex, typically PEO with a lithium salt, replaces the liquid electrolyte as ion conductor and separator.

Solid Power

Solid Power Inc. is a Colorado-based battery developer, founded in 2011 as a University of Colorado Boulder spinout, that makes sulfide-based all-solid-state cells and electrolytes for electric vehicles.

Solid solution strengthening

Solid solution strengthening, also called solid solution hardening, is a metallurgical method that strengthens metals when dissolved solute atoms impede dislocation glide in the crystal lattice.

Solid State Logic

Solid State Logic (SSL) is a British audio mixing console manufacturer founded in 1969, based in Begbroke, Oxfordshire, best known for the SL 4000 series.

Solid State Phased Array Radar System

A solid state phased array radar system (SSPARS) is a radar with a fixed antenna whose beam is steered electronically by solid state transmit/receive modules.

Solid-electrolyte CO2 electrolysis

Solid-electrolyte CO2 electrolysis covers two approaches using a solid ion conductor: high-temperature solid oxide cells making CO or syngas, and low-temperature reactors making pure formic acid.

Solid-propellant rocket

A solid-propellant rocket, also called a solid rocket motor, is a rocket with fuel and oxidizer cast together as a solid grain that burns from exposed surfaces.

Solid-state battery

A solid-state battery, also called a solid battery, is a rechargeable battery in which a solid electrolyte replaces the flammable liquid of lithium-ion cells, enabling lithium-metal anodes.

Solid-state circuit breaker

A solid-state circuit breaker is an electrical protection device that interrupts fault current with power semiconductor switches in microseconds, aimed mainly at fast-rising DC fault currents.

Solid-state composite cathode

A solid-state composite cathode is the positive electrode of an all-solid-state battery, a solid mix of active material, solid electrolyte, carbon, and binder that must conduct ions and electrons.

Solid-state drive

A solid-state drive (SSD) is a data storage device that uses non-volatile NAND flash memory instead of spinning platters, making it faster and more shock-resistant than a hard disk drive.

Solid-state electronics

Solid-state electronics is the branch of electronics in which current flows through solid semiconductors, chiefly silicon, rather than vacuum tubes; born with the 1947 Bell Labs transistor, it underlies virtually every modern electronic product.

Solid-state power amplifier

A solid-state power amplifier (SSPA) is a high-power radio-frequency amplifier built from GaN or GaAs semiconductor transistors rather than vacuum tubes, widely used in satellite uplinks.

Solid-state relay

A solid-state relay (SSR) is an electronic switching device that uses semiconductors such as triacs, thyristors, or MOSFETs to switch a load with no moving parts.

Sep 29, 2026

Solid-state sintering

Solid-state sintering is a powder-metallurgy process in which compacted powder particles bond and densify into a solid by heating below the melting point, driven by atomic diffusion.

Solid-state sodium battery

A solid-state sodium battery is a rechargeable battery in which a solid electrolyte replaces the flammable liquid between electrodes, offering sodium's low cost, improved safety, and higher energy density.

Solid-state transformer

A solid-state transformer (SST) is a power electronics-based device that converts voltage with semiconductor converters and a compact medium-frequency transformer, adding functions like fault current limiting and bidirectional power flow control.