SOL 101 › Glossary
SOL 101 glossary
Every technical term and abbreviation used in SOL 101, in plain language: 369 entries. Each links to the page where it is first explained.
Columns: the term or abbreviation; its full name (for abbreviations) or symbol and unit; a plain-language definition; and where it is introduced. "—" means the term is not an abbreviation.
A B C D E F G H I J K L M N O P Q R S T U V W X Z
| Term | Full name / symbol | Plain definition | Introduced |
|---|---|---|---|
| Absolute value | | | | A number without its minus sign. | Unit 9 |
| Absolute zero | 0 K = −273.15 °C | The lowest possible temperature, where random atomic motion is at its minimum. | Unit 2 |
| Absorptance | — | Fraction of incident light that is absorbed. | Unit 5 |
| Absorption (atmospheric) | — | A molecule taking up a photon's energy, eventually turning it into heat. | Unit 7 |
| Absorption band | — | Range of wavelengths a particular molecule absorbs. | Unit 7 |
| Aerosol | — | Tiny particles suspended in air: dust, smoke, sea salt, pollution. | Unit 7 |
| Air mass | AM | Path length of sunlight through the atmosphere relative to the overhead path; AM ≈ 1/cos θz. | Unit 7 |
| Albedo | 0–1 | Fraction of light a surface (e.g. the ground) reflects. Grass ≈0.2, snow ≈0.8–0.9. | Unit 9 |
| AM0 | air mass zero | The spectrum of sunlight above the atmosphere (no air crossed). | Unit 5 |
| AM1.5D | air mass 1.5, direct | The direct beam (plus circumsolar) portion of the standard spectrum, ≈900 W/m². | Unit 7 |
| AM1.5G | air mass 1.5, global | The standard ground spectrum on a 37°-tilted surface, normalised to 1000 W/m². | Unit 7 |
| Ambient temperature | T_air | Temperature of the surrounding air. | Unit 10 |
| Ampere (amp) | A | SI unit of current: one coulomb per second, about 6.24 × 10¹⁸ electrons per second. | Unit 1 |
| Amplitude | — | Height of a wave's oscillation; intensity goes as amplitude squared. | Unit 3 |
| Angle of incidence | θ | Angle between an incoming ray and the surface normal; 0° = face-on. | Unit 9 |
| ANSI | American National Standards Institute | US standards body; e.g. ANSI Z87.1 for safety glasses, ANSI A1–A9 cut levels for gloves. | Starter kit |
| Anti-reflection coating | ARC | A thin transparent film (≈75 nm silicon nitride on cells) that cancels reflections by interference. | Unit 3 |
| AOD | aerosol optical depth | How much haze dims the direct beam; transmission ≈ e^(−AOD). | Unit 7 |
| a-Si | amorphous silicon | Non-crystalline silicon, band gap ≈1.7 eV, used in thin films. | Unit 7 |
| a-Si:H | hydrogenated amorphous silicon | Non-crystalline silicon containing hydrogen; passivating layers in HJT cells. | Unit 11 |
| ASTM E490 | — | ASTM International standard AM0 spectrum for space applications (≈1366 W/m²). | Unit 6 |
| ASTM G173 | ASTM International standard G173 (ASTM: originally American Society for Testing and Materials) | The table that defines standard reference sunlight spectra (AM0, AM1.5G, AM1.5D) for the industry. | Unit 3 |
| Astronomical unit | AU = 1.496 × 10⁸ km | Average Earth–Sun distance. | Unit 5 |
| Atmosphere-centimetre | atm·cm | Thickness the ozone layer would have at sea-level pressure. | Unit 7 |
| Atomic oxygen | — | Single oxygen atoms in low Earth orbit that erode exposed polymers. | Unit 6 |
| Attenuate | — | To reduce the intensity of light (or a signal), e.g. with layers of window screen. | Lab B |
| Auger recombination | — | Unavoidable loss in which an excited electron gives its energy to another electron as heat; sets silicon's 29.4 % intrinsic limit. | Unit 2 |
| Axial tilt | 23.44° | Tilt of Earth's spin axis; the cause of seasons. | Unit 6 |
| Back contact | — | Metal contact on the rear of a cell. | Unit 11 |
| Back-contact cell | — | Cell with all contacts on the rear, so nothing shades the front. | Unit 11 |
| Backsheet | — | Plastic film forming the rear of a standard (monofacial) module. | Unit 9 |
| Band edge | — | Wavelengths just short of the cutoff, where absorption is weak. | Unit 4 |
| Band (energy band) | — | Continuous range of allowed electron energies formed when atomic levels overlap in a solid. | Unit 11 |
| Band gap | E_g; unit eV | Minimum energy needed to free an electron in a solid so it can carry current. Silicon: 1.12 eV. | Unit 1 |
| Beer–Lambert law | — | Light passing through equal thicknesses of an absorber is reduced by equal fractions, so intensity falls exponentially with thickness. | Lab B |
| Bench power supply | — | An adjustable source of steady DC voltage and current with built-in meters. | Lab C |
| Bifaciality | % | Ratio of rear-side to front-side efficiency at STC. | Unit 9 |
| Bifacial module | — | A module that collects light on both front and rear faces. | Unit 9 |
| Binning | — | Sorting finished cells or modules into classes by measured power, current or voltage. | Unit 10 |
| Blackbody | — | An ideal object that absorbs all light at every wavelength and therefore emits the maximum possible thermal radiation for its temperature. | Unit 5 |
| Blackbody radiation | — | Light a hot object emits purely because of its temperature (detailed in Unit 5). | Unit 2 |
| Boltzmann's constant | k_B = 1.381 × 10⁻²³ J/K | Converts temperature into typical thermal energy per particle; k_BT ≈ 0.026 eV at 300 K. | Unit 5 |
| Brewster's angle | arctan(n₂/n₁) | Angle at which reflected light is fully polarised (56° for glass). | Unit 9 |
| Built-in electric field | — | Permanent field inside a cell, created by joining two differently doped layers, that sorts charges to make a voltage. | Unit 4 |
| Bulk | — | The interior of a wafer, as opposed to its surfaces. | Unit 4 |
| Calibration | — | Matching an instrument's readings to known reference values (e.g. known emission-line wavelengths) so it reads correctly. | Lab A |
| Carnot limit | η_C = 1 − T_c/T_h | Maximum efficiency of any heat engine between hot temperature T_h and cold temperature T_c (in kelvin). | Unit 2 |
| CAT III | measurement category III | A multimeter safety rating (IEC 61010) for withstanding voltage spikes found on building wiring. | Starter kit |
| CdTe | cadmium telluride | Compound semiconductor (band gap ≈1.5 eV) used in thin-film panels. | Unit 4 |
| CFL | compact fluorescent lamp | An energy-saving lamp: mercury vapour emits ultraviolet light that a phosphor coating converts to visible light, giving a spiky spectrum. | Lab A |
| Circumsolar light | — | Bright scattered glow just around the Sun's disc. | Unit 7 |
| Cloud enhancement | — | Brief irradiance above clear-sky values from sunlight reflected off cloud edges. | Unit 10 |
| CODATA | Committee on Data of the International Science Council | Publishes recommended values of physical constants. | Unit 4 |
| Colour temperature | — | The temperature of a blackbody whose glow has the same colour as a given light source; warm-white lamps are ~2700 K, daylight ~5800–6500 K. | Lab A |
| COM jack | common jack | The multimeter's reference (black-lead) socket. | Lab B |
| Concentration | "suns" | Focusing sunlight with lenses or mirrors; maximum possible ≈ 46,000 times. | Unit 2 |
| Concentrator | — | System of lenses or mirrors focusing direct sunlight onto small cells. | Unit 7 |
| Conduction band | — | Range of energies where electrons are free to move and carry current. | Unit 11 |
| Conservation of energy | first law of thermodynamics | Energy cannot be created or destroyed, only converted from one form to another. | Unit 1 |
| Constant-voltage mode | — | Power-supply setting that holds the chosen voltage and lets the current be whatever the load draws. | Lab C |
| Constellation (satellite) | — | A fleet of many satellites working together (e.g. Starlink). | Unit 6 |
| Convection | — | Heat carried away by moving air or liquid. | Unit 2 |
| Cosine | cos | Trigonometric function: adjacent side ÷ longest side; 1 at 0°, 0 at 90°. | Unit 6 |
| Cosine law | G_surface = G_beam cos θ | A beam striking at angle θ from the normal spreads over more area, so irradiance falls as cos θ. | Unit 9 |
| Coulomb | C | SI unit of charge: the charge of about 6.24 × 10¹⁸ electrons. | Unit 1 |
| Coverglass | — | Thin protective glass bonded over each space solar cell. | Unit 6 |
| Cross-section | A | Area a beam covers on a sheet held square to it. | Unit 9 |
| Crystal / lattice | — | Solid whose atoms sit in a regularly repeating 3-D pattern / that pattern. | Unit 11 |
| c-Si | crystalline silicon | Silicon with an ordered crystal lattice: the material of mainstream cells. | Unit 10 |
| CSV | comma-separated values | Plain-text table format readable by spreadsheets and programs. | Unit 8 |
| Current density | J; unit mA/cm² | Current divided by cell area, so cells of different sizes can be compared. Silicon ≈ 40 mA/cm². | Unit 1 |
| Current matching | — | Requirement that stacked sub-cells wired in series produce the same current. | Unit 4 |
| Cutoff wavelength | λ_g = 1239.84/E_g | Longest wavelength a material can absorb (its band gap converted to wavelength). Silicon: 1107 nm. | Unit 4 |
| Czochralski puller | Cz | Furnace that grows a single silicon crystal by slowly pulling a seed from molten silicon. | Unit 5 |
| Dark current | — | A cell's internal diode current that flows back across the junction and subtracts from the light-generated current. | Unit 5 |
| Dark frame | — | A photo taken with the light blocked, subtracted from measurements to remove the camera's background signal. | Lab A |
| Datasheet | — | A manufacturer's specification sheet listing a module's rated power, voltages, currents and temperature coefficients. | Course overview |
| Declination | δ (delta) | Latitude where the Sun is overhead at noon; ±23.44° at the solstices. | Unit 9 |
| Depletion region | — | Thin layer at a p-n junction emptied of mobile carriers, where the built-in field sits. | Unit 11 |
| Detailed balance | — | Calculation method balancing every photon absorbed against every photon the cell must re-emit. | Unit 2 |
| DHI | diffuse horizontal irradiance | Sky (scattered) irradiance on a horizontal surface. | Unit 7 |
| Diffraction | — | Spreading of a wave through a narrow opening or around an edge. | Unit 3 |
| Diffraction grating | line spacing d | Sheet of fine parallel lines that sends each wavelength off at its own angle: d sin θ = mλ. | Unit 3 |
| Diffusion | — | Spreading of particles from crowded to sparse regions by random motion. | Unit 11 |
| Digital multimeter | — | A handheld meter that measures voltage, current and resistance. | Lab B |
| Diode | — | One-way electrical valve that conducts easily in only one direction. A solar cell is a large diode. | Unit 10 |
| Direct current | DC | Current that flows in one direction only, as from a cell or battery (opposite of the alternating current, AC, from a wall socket). | Lab B |
| Direct / diffuse / global light | — | Beam from the Sun's disc / scattered sky light / their total on a surface. | Unit 7 |
| DNI | direct normal irradiance | Beam irradiance from the Sun's disc on a surface facing the Sun. | Unit 7 |
| Doping | — | Adding tiny amounts of impurity atoms to a semiconductor to make it p-type (boron) or n-type (phosphorus). | Unit 10 |
| Draper point | — | About 798 K: the temperature at which nearly all solids begin to glow visibly red. | Lab C |
| E26 | Edison screw, 26 mm | The standard US screw-in light-bulb base. | Starter kit |
| Eccentricity | e | How stretched an ellipse is; 0 = circle. Earth's orbit: 0.0167. | Unit 6 |
| Effective temperature | T_eff = 5772 K (Sun) | Temperature of a blackbody of the same size that radiates the same total power. | Unit 5 |
| Efficiency | η (eta) | Electrical power out divided by light power in, η = P_max / (G × A). | Unit 1 |
| EIA | U.S. Energy Information Administration | U.S. government statistics agency for energy. | Unit 1 |
| Electrical power | P = VI | Power delivered by a current: voltage × current. | Unit 1 |
| Electric charge | q or Q; unit coulomb (C) | A basic property of particles; comes as positive or negative. Like charges repel, opposite charges attract. | Unit 1 |
| Electric current | I; unit ampere (A) | The rate at which charge flows past a point, in coulombs per second. | Unit 1 |
| Electric field | unit V/m | At each point in space, the push (strength and direction) a small charge placed there would feel. | Unit 3 |
| Electroluminescence | EL | Light emitted when current is driven through a semiconductor; used to image cracks and defects. | Unit 5 |
| Electromagnetic spectrum | EM spectrum | All electromagnetic waves arranged by wavelength: radio, microwave, infrared, visible, ultraviolet, X-ray, gamma. | Unit 3 |
| Electromagnetic wave | — | Self-sustaining ripple of electric and magnetic fields that travels at the speed of light. Light, radio and X-rays are all examples. | Unit 3 |
| Electron | e⁻ | Light, negatively charged particle that surrounds an atom's nucleus; the carrier of current in metals and (partly) in solar cells. | Unit 1 |
| Electron–hole pair | — | A freed electron together with the hole it left behind; created by one absorbed photon. | Unit 11 |
| Electron-volt | eV | Energy one electron gains moving through one volt: 1.602 × 10⁻¹⁹ J. Used for photons and band gaps. | Unit 1 |
| Elementary charge | e = 1.602 × 10⁻¹⁹ C | The size of the charge on one electron (or one proton). | Unit 1 |
| Emission lines | — | Sharp, bright colours at exact wavelengths given off by a gas lamp (e.g. mercury in a fluorescent tube); used to calibrate a spectroscope. | Lab A |
| Emissivity | ε (epsilon), 0–1 | How much an object emits compared with a perfect blackbody at the same temperature. | Unit 5 |
| Empirical formula | — | An equation fitted to measurements rather than derived from theory. | Unit 7 |
| Encapsulant | — | Clear plastic sheet that glues cells to the glass and seals out moisture. | Unit 2 |
| Encapsulation | — | Sealing cells behind glass with plastic encapsulant. | Unit 11 |
| Energy | E; unit joule (J) | The capacity to do work: to push, lift, heat or light something. Never created or destroyed, only converted between forms. | Unit 1 |
| Energy level | — | One of the sharp allowed energies of an electron in an isolated atom. | Unit 11 |
| Energy yield | kWh per year | Electricity a system actually delivers over time. | Unit 7 |
| Entropy | S; unit J/K | A count of how many microscopic arrangements fit what we observe: how spread out energy is. | Unit 2 |
| Equinox / solstice | — | Equal day and night (March, September) / Sun farthest north or south (June, December). | Unit 7 |
| EVA | ethylene-vinyl acetate | The most common encapsulant plastic in modules. | Unit 3 |
| Extraterrestrial irradiance | — | Sunlight irradiance just outside Earth's atmosphere. | Unit 6 |
| Fermi level | E_F | Energy describing how full the bands are; developed in SOL 201–202. | Unit 11 |
| Filament | — | The thin tungsten wire in an incandescent bulb that glows when heated by current. | Lab C |
| Fill factor | FF | How "square" a cell's current–voltage curve is: P_max ÷ (V_oc × I_sc). | Unit 8 |
| Firing furnace | — | Belt furnace that bakes printed metal contacts onto cells at ~750–800 °C. | Unit 5 |
| First law of thermodynamics | — | Energy in = energy out + energy stored. Energy is conserved. | Unit 2 |
| Flash tester | — | Factory machine that fires a calibrated flash of artificial sunlight at a module and measures its electrical output. | Unit 1 |
| Flat-plate module | — | An ordinary flat panel, which uses both direct and diffuse light. | Unit 7 |
| Force | F; unit newton (N) | A push or a pull. One newton is roughly the weight of a 100-gram apple. | Unit 1 |
| Fraunhofer ISE | Fraunhofer Institute for Solar Energy Systems | German solar research institute; publishes the Photovoltaics Report. | Unit 11 |
| Fraunhofer lines | — | Dark lines in the Sun's spectrum where elements in its cooler outer layers absorb. | Unit 5 |
| Free carriers | — | Electrons (or holes) already free to move; they can absorb low-energy light and turn it into heat. | Unit 4 |
| Frequency | f; unit hertz (Hz) | Number of wave crests passing a point per second. | Unit 3 |
| Fresnel equations | R = ((n₁−n₂)/(n₁+n₂))² at normal incidence | Formulas for how much light reflects at a boundary for each angle and polarisation. | Unit 9 |
| Fresnel reflection | — | Partial reflection whenever light crosses a change in refractive index; grows at steep angles. | Unit 9 |
| GaAs | gallium arsenide | Compound semiconductor (band gap 1.42 eV) used in high-efficiency and space cells. | Unit 4 |
| Germanium | Ge | Semiconductor element, band gap 0.67 eV; bottom layer of many space cells. | Unit 8 |
| GHI | global horizontal irradiance | Total irradiance on a horizontal surface: GHI = DNI cos θz + DHI. | Unit 7 |
| Glass–glass laminate | — | Module with glass on both faces bonded by encapsulant. | Unit 9 |
| Grazing incidence | θ near 90° | Light skimming almost parallel to a surface; reflectance approaches 100 %. | Unit 9 |
| Greybody | — | An emitter with emissivity below 1 but roughly constant across wavelengths. | Unit 5 |
| Half-angle (Sun) | ≈0.267° | Angle from the centre to the edge of the Sun's disc as seen from Earth. | Unit 6 |
| Heat | Q; unit joule | Disordered energy transfer from hotter to colder objects, driven by a temperature difference. | Unit 2 |
| Heat conduction | — | Heat flowing through solid material from hotter to colder parts. | Lab C |
| Heat engine | — | A device that turns heat into work and must reject some waste heat (car engine, steam turbine). | Unit 2 |
| Hertz | Hz | One cycle per second. | Unit 3 |
| HJT | heterojunction (technology) | Cell design with thin amorphous-silicon layers on crystalline silicon; high bifaciality. | Unit 9 |
| Hole | h⁺ | The vacancy left when an electron leaves a bond; moves like a positive charge. | Unit 11 |
| Hot spot | — | A shaded or damaged cell forced to absorb power from its neighbours, overheating. | Unit 2 |
| Hot zone | — | The heated, insulated core of a crystal-growth furnace. | Lab C |
| IAM | incidence angle modifier | Datasheet curve: light coupled into cells at angle θ relative to normal incidence, beyond the cosine factor. | Unit 9 |
| IAU | International Astronomical Union | Body that sets astronomical standards and nominal solar values. | Unit 5 |
| Ideality factor | n (1–2) | Number describing how close a diode is to ideal behaviour. | Unit 10 |
| IEC | International Electrotechnical Commission | Body that writes international electrical and solar test standards (e.g. IEC 60904). | Unit 5 |
| IEC 61215 | — | IEC design-qualification test standard for terrestrial modules. | Unit 10 |
| III–V cells | — | Cells made of compounds of elements from periodic-table columns III and V (e.g. GaAs, GaInP). | Unit 6 |
| Incandescent / halogen lamp | — | Lamps that make light by heating a tungsten filament; mostly infrared output. | Unit 5 |
| Index matching | — | Using materials with similar refractive indices so internal boundaries barely reflect. | Unit 9 |
| Indirect band gap | — | Gap where a photon alone cannot lift an electron; a lattice vibration must take part (silicon). Weak absorption near the edge. | Unit 11 |
| Infrared | IR | Light with wavelengths longer than red (beyond ≈750 nm); invisible. | Unit 3 |
| Infrared thermography | — | Imaging temperature with an infrared camera, e.g. to find hot, defective cells. | Unit 5 |
| Integral sign | ∫ … dλ | Notation for "add up thin slices of" a quantity between two limits. | Unit 8 |
| Integrate | — | Add up a quantity over time (or another variable): the area under its curve. | Unit 1 |
| Intensity | — | Power carried per unit area by a wave (same idea as irradiance). | Unit 3 |
| Interconnect | — | Copper ribbons or wires that join neighbouring cells. | Unit 2 |
| Interference | — | Adding of overlapping waves: crests on crests reinforce (constructive), crests on troughs cancel (destructive). | Unit 3 |
| Internal transition | — | A molecule's jump between allowed energy states, which lets it absorb a photon of matching energy. | Unit 7 |
| Intrinsic carrier concentration | n_i | Free electrons (and holes) per cm³ in pure silicon from heat alone; rises steeply with temperature. | Unit 10 |
| Inverse-square law | G = L/(4πd²) | Irradiance from a point-like source falls with the square of distance. | Unit 6 |
| Inverter | — | Electronics that converts a module's direct current into the alternating current used by the grid. | Unit 1 |
| IR-cut filter | infrared-cut filter | A filter in phone cameras that blocks infrared light, so the camera under-reports the red end of a spectrum. | Lab A |
| Irradiance | G; unit W/m² | Power of light arriving per square metre of surface. Full sun ≈ 1000 W/m². | Unit 1 |
| Irradiation (insolation) | unit kWh/m² | Light energy received per square metre over a period (day or year): irradiance integrated over time. | Unit 1 |
| Irreversibility | — | Any real-world process (friction, heat leaking across a temperature gap) that creates extra entropy and lowers efficiency. | Unit 2 |
| ISO | International Organization for Standardization | International standards body (e.g. ISO 15387 for space cells). | Unit 6 |
| ITRPV | International Technology Roadmap for Photovoltaic | Annual industry report with production statistics and technology trends. | Unit 1 |
| I–V curve | current–voltage curve | Graph of a cell's current against its voltage as the load varies from short to open circuit. | Unit 10 |
| Joule | J | The SI unit of energy: the work done by a one-newton force acting over one metre. About the energy to lift an apple one metre. | Unit 1 |
| Junction | — | In this context, one light-absorbing layer with its own band gap. | Unit 2 |
| Kasten–Young formula | — | Fitted air-mass formula that accounts for Earth's curvature. | Unit 7 |
| Kelvin | K | Temperature scale starting at absolute zero with Celsius-sized steps: K = °C + 273.15. Required in any temperature ratio. | Unit 2 |
| Kilowatt-hour | kWh | Energy unit: 1000 watts for one hour = 3.6 million joules. The unit on electricity bills. | Unit 1 |
| Kinetic energy | KE = ½mv² | Energy of motion. | Unit 4 |
| Kirchhoff's law of thermal radiation | — | At each wavelength, a body's absorptance equals its emissivity: good absorbers are good emitters. | Unit 5 |
| Landsberg limit | η_L ≈ 93 % | Maximum work extractable from sunlight treated as blackbody radiation, accounting for the entropy of light. | Unit 2 |
| Latitude | — | Angle north or south of the equator. | Unit 7 |
| LED | light-emitting diode | Semiconductor chip that emits a narrow band of colour when current flows. | Unit 5 |
| Light trapping | — | Texture and reflectors that make light bounce inside a cell so weakly absorbed wavelengths are captured. | Unit 3 |
| Limb darkening | — | The Sun's disc looks darker near its edge, where we see only cooler upper layers. | Unit 5 |
| Linearity | — | A property where doubling the input exactly doubles the output; I_sc is linear in irradiance. | Lab B |
| Load | — | Anything connected to a cell that uses its electricity. | Unit 11 |
| Log scale | logarithmic scale | A chart axis where each equal step is a factor of ten, so tiny and huge values fit together. | Unit 1 |
| Luminosity | L; unit W | Total power radiated by a star in all directions. | Unit 6 |
| Lux | lux (lumens per square metre) | A unit of brightness weighted by the human eye's sensitivity; it ignores infrared light that solar cells can use. | Lab A |
| Magnetic field | — | The influence created by moving charges (currents) that turns a compass needle. | Unit 3 |
| Maximum power | P_max (also Pmax, P_mp) | The highest electrical power a cell or module can deliver at a given light and temperature. | Unit 1 |
| Maximum power point | MPP | The point on the I–V curve where V × I is largest. | Unit 10 |
| Maximum power point tracker | MPPT | Electronics that keep a system operating at the MPP. | Unit 11 |
| Metallization | — | Printing the metal fingers and busbars that collect current from a cell. | Unit 11 |
| Micrometre (micron) | µm | One millionth of a metre (10⁻⁶ m) = 1000 nm. | Unit 3 |
| Mid-latitude / tropics | — | Roughly 30–55° from the equator / between 23.4° N and S. | Unit 7 |
| Mie scattering | — | Scattering by particles about the size of the wavelength; nearly colour-neutral (white haze). | Unit 7 |
| Milliamp | mA | One thousandth of an amp (0.001 A). | Lab B |
| Millisecond | ms | One thousandth of a second. | Unit 10 |
| Millivolt | mV | One thousandth of a volt. | Unit 10 |
| Mismatch | — | Cells or modules in series with unequal currents; the weakest limits the string. | Unit 10 |
| Module (panel) | — | Many cells wired together and sealed behind glass in a frame for 25–30 years of outdoor use. | Unit 1 |
| Monochromatic | — | Light of a single wavelength. | Unit 4 |
| Monocrystalline silicon | mono-Si | Silicon cut from a single large crystal; the common high-efficiency solar-cell material. | Lab B |
| Multi-junction (tandem) cell | — | A cell stacking several absorber layers with different band gaps to use more of the spectrum. | Unit 2 |
| Nanometre | nm | One billionth of a metre (10⁻⁹ m). | Unit 3 |
| Natural logarithm | ln | Power to which e ≈ 2.718 must be raised to give a number; grows very slowly. | Unit 10 |
| NIR | near-infrared | Infrared light just beyond red (roughly 700–2500 nm); silicon cells use the part up to ~1100 nm. | Starter kit |
| NMOT | nominal module operating temperature | Like NOCT but with the module operating at maximum power (IEC 61215:2016). | Unit 10 |
| NOCT | nominal operating cell temperature | Cell temperature of an open-circuited module at 800 W/m², 20 °C air, 1 m/s wind, open rack. | Unit 10 |
| Non-linear resistance | — | Resistance that changes with conditions (such as temperature), so current is not proportional to voltage. | Lab C |
| Normal | — | The line perpendicular to a surface; angles of incidence are measured from it. | Unit 3 |
| Normal incidence | θ = 0° | Light arriving square to a surface. | Unit 9 |
| NREL | National Renewable Energy Laboratory (renamed National Laboratory of the Rockies, NLR) | US national renewable-energy research lab. | Unit 7 |
| n-type / p-type | — | Silicon doped to have excess free electrons (phosphorus) / excess holes (boron). | Unit 11 |
| Nucleus | — | The small, heavy, positively charged centre of an atom, made of protons and neutrons. | Unit 1 |
| Ohm | Ω | SI unit of resistance: 1 Ω lets 1 A flow when 1 V is applied. | Unit 1 |
| Ohm's law | V = IR | For many materials, voltage = current × resistance. | Unit 1 |
| One sun | — | Normal, unconcentrated sunlight (≈1000 W/m²). | Unit 11 |
| Open-circuited | — | Terminals not connected, so no current flows. | Unit 10 |
| Open-circuit voltage | V_oc | Voltage of a cell when no current is drawn; ≈0.7 V for modern silicon. | Unit 10 |
| Order of magnitude | — | One factor of ten. | Unit 1 |
| Ozone | O₃ | Three-atom oxygen molecule; the ozone layer absorbs most ultraviolet below ~300–320 nm. | Unit 7 |
| Passivation | — | Chemical treatment of a surface so it wastes (recombines) fewer electrons. | Unit 2 |
| Peak sun hours | — | Daily irradiation expressed as the equivalent number of hours at 1000 W/m². | Unit 1 |
| PECVD | plasma-enhanced chemical vapour deposition | Thin-film coating process where gases react in an electrically energised glow (plasma). | Unit 3 |
| PERC | passivated emitter and rear cell | The previous mainstream silicon cell design, with a passivating insulating layer on the rear. | Unit 2 |
| Percentage point | — | The arithmetic difference between two percentages (33.7 % − 33.4 % = 0.3 points). | Unit 11 |
| Perihelion / aphelion | — | Earth's closest (early January) and farthest (early July) points from the Sun. | Unit 6 |
| Perovskite | — | Family of crystal compounds with tunable band gaps, promising for tandems. | Unit 7 |
| Phosphor | — | A coating that absorbs light (often ultraviolet or blue) and re-emits it at longer wavelengths; used in fluorescent lamps and white LEDs. | Lab A |
| Photoelectric effect | KE_max = hf − W | Light knocking electrons out of a metal, only above a threshold frequency; proof that light comes in photons. | Unit 4 |
| Photon | — | A single, indivisible packet of light energy. | Unit 1 |
| Photon energy | E = hc/λ; E[eV] = 1239.84/λ[nm] | Energy of one photon; larger for shorter (bluer) wavelengths. | Unit 4 |
| Photon flux | Φ (phi); unit s⁻¹ m⁻² | Number of photons arriving per second per square metre: Φ = Pλ/(hc). | Unit 4 |
| Photosphere | — | The Sun's visible surface layer from which light escapes. | Unit 5 |
| Photovoltaic | PV | Direct conversion of light into electricity in a solid material, with no moving parts ("photo" = light, "voltaic" = electricity). | Unit 1 |
| Photovoltaic effect | — | Light creating a voltage and current inside a semiconductor; discovered by Becquerel in 1839. | Unit 4 |
| Picosecond | ps | One trillionth (10⁻¹²) of a second. | Unit 11 |
| Planck's constant | h = 6.626 × 10⁻³⁴ J·s | Constant of nature setting the size of energy packets: photon energy E = hf. | Unit 4 |
| Planck's law | B_λ(T) | Formula for how much light a blackbody emits at each wavelength for a given temperature. | Unit 5 |
| p-n junction | — | Boundary between p-type and n-type semiconductor layers; its built-in field separates charges. | Unit 10 |
| Polarisation | — | The direction in which light's electric field oscillates. Sunlight is unpolarised (an even mix). | Unit 9 |
| Polymer | — | A material made of long chain molecules: plastics like EVA. | Unit 3 |
| Poly-Si | polycrystalline silicon | Silicon made of many tiny crystals; thin doped layer in TOPCon contacts. | Unit 11 |
| Polysilicon | polycrystalline silicon | Ultra-pure silicon raw material, made of many small crystals, melted to grow the crystals that wafers are cut from. | Unit 1 |
| Porous-silica AR coating | — | Porous silicon-dioxide film on module glass with an index between air and glass. | Unit 9 |
| Power | P; unit watt (W) | Rate of energy flow or use: energy per unit time. | Unit 1 |
| Power matrix | IEC 61853 | Module maximum power measured at a grid of irradiances and temperatures. | Unit 10 |
| Precipitable water | cm | Depth of liquid water if all vapour in a vertical air column condensed. | Unit 7 |
| Primary energy | — | All energy taken from nature (fuels, nuclear, hydro, wind, solar) before conversion losses. World ≈ 20 TW. | Unit 1 |
| Primary standard | — | The top reference in a calibration chain, measured directly by a national laboratory. | Unit 6 |
| P–V curve | power–voltage curve | Power plotted against voltage; peaks at the MPP. | Unit 11 |
| pvlib | — | Free, open-source Python library of solar calculations. | Unit 8 |
| Pyramid texture | — | Microscopic pyramids etched into a wafer so reflected light gets a second chance to enter. | Unit 9 |
| Pyrometer | — | Non-contact thermometer that reads an object's infrared glow. | Unit 5 |
| Qualification | — | Standardised testing to prove a product survives its intended environment. | Unit 6 |
| Quantised | — | Coming only in whole packets (quanta), never in fractions of one. Light energy is quantised into photons. | Unit 4 |
| Quantum efficiency | QE | Fraction of photons at each wavelength that end up as electrons in the circuit. | Unit 3 |
| Quarter-wave coating | thickness = λ/(4n) | Film thickness at which top and bottom reflections cancel. | Unit 3 |
| Radiant exitance | M; W/m² | Total power emitted per square metre of surface. | Unit 5 |
| Radiative recombination | — | A freed electron falling back across the gap and emitting a photon; unavoidable, sets the SQ limit. | Unit 8 |
| Radiative-transfer model | — | Program that follows light through a model atmosphere applying absorption and scattering. | Unit 7 |
| Radiometer | — | Instrument that measures total light power by the heating of a blackened absorber. | Unit 6 |
| Rated voltage | — | The operating voltage printed on a bulb or device. | Lab C |
| Rayleigh scattering | ∝ 1/λ⁴ | Scattering by molecules much smaller than the wavelength; strongly favours blue (why the sky is blue). | Unit 7 |
| Recombination | — | A free electron falling back into a hole, losing its energy as heat or light. | Unit 11 |
| Recombination current | — | Current lost when freed electrons and holes recombine before being collected. | Unit 5 |
| Reference cell | — | A carefully calibrated cell used to set the intensity of a simulator. | Unit 6 |
| Reflectance | R | Fraction of light reflected at each wavelength. | Unit 3 |
| Refraction | — | The bending of light as it crosses a boundary between materials at a slant. | Unit 3 |
| Refractive index | n | How much slower light travels in a material than in vacuum (v = c/n). | Unit 3 |
| Reservoir | — | A body so large its temperature does not change when heat flows in or out. | Unit 2 |
| Resistance | R; unit ohm (Ω) | How strongly a material opposes current; the ratio of voltage to current. Comes from electrons colliding with atoms, which makes heat. | Unit 1 |
| Resistive (I²R) loss | P = I²R | Power turned into heat when current flows through a resistance; grows with the square of current. | Unit 1 |
| Resistivity | ρ; unit Ω·m | A material's intrinsic resistance for a standard sample size. | Unit 5 |
| Saturation current | I_0 (J_0 per area) | Tiny diode leakage current that flows back across the junction; sets V_oc. | Unit 10 |
| Scattering | — | Light redirected in a new direction without being absorbed. | Unit 7 |
| Scientific notation | a × 10ⁿ | Writing numbers as a value from 1 to 10 times a power of ten, e.g. 1.7 × 10¹⁷. | Unit 1 |
| Screen printing | — | Pushing silver paste through a patterned mesh to form cell contacts. | Unit 11 |
| Second law of thermodynamics | — | In any real process total entropy increases; heat flows spontaneously only from hot to cold. | Unit 2 |
| Semiconductor | — | Material whose conductivity lies between a metal's and an insulator's and can be controlled (e.g. silicon). | Unit 4 |
| Series connection | — | Cells wired end to end so their voltages add while the same current flows through all. | Lab B |
| Series resistance | R_s | Resistance of the cell's metal and silicon in the current path; causes I²R loss. | Unit 10 |
| Shading (metal) | — | Light blocked by the metal contact lines printed on a cell's front. | Unit 4 |
| Shockley–Queisser limit | SQ limit | The maximum efficiency (≈33.7 %) of a solar cell with a single band gap under standard sunlight, from Shockley and Queisser (1961). | Unit 2 |
| Short circuit | — | A near-zero-resistance path between two terminals; for a solar cell it gives the short-circuit current. | Lab B |
| Short-circuit current | I_sc (density J_sc) | Current a cell delivers with its terminals connected directly (zero voltage): the most current it can give. | Unit 8 |
| Shunt | — | A precise low-value resistor inside a meter; the meter measures the small voltage across it and divides by its resistance to show current. | Lab B |
| SI | Système international d'unités (International System of Units) | The worldwide agreed set of measurement units: metre, kilogram, second, ampere, kelvin and others. | Unit 1 |
| Silicon nitride | SiNₓ | Compound of silicon and nitrogen used as the cell anti-reflection and passivation coating. | Unit 3 |
| Sine | sin | Trigonometric function: opposite side ÷ longest side of a right triangle; 0 at 0°, 1 at 90°. | Unit 3 |
| Single-diode model | — | Standard equivalent circuit of a cell: current source, diode and resistances. | Unit 10 |
| Single-junction cell | — | A cell with one absorber and one band gap. | Unit 11 |
| SMARTS | Simple Model of the Atmospheric Radiative Transfer of Sunshine | Radiative-transfer program used to generate ASTM G173. | Unit 7 |
| Snell's law | n₁ sin θ₁ = n₂ sin θ₂ | The rule for how much light bends at a boundary. | Unit 3 |
| Soiling | — | Dust and dirt on the module glass that blocks light. | Unit 1 |
| SOL | — (course-code prefix, "solar") | The curriculum's course numbering; SOL 101 and 102 are the introductory courses, higher numbers are later courses. | Course overview |
| Solar cell | — | The basic light-to-electricity device, usually a treated silicon wafer with metal contacts. | Unit 1 |
| Solar constant | ≈ 1361 W/m² | Sunlight irradiance just above Earth's atmosphere at the average Earth–Sun distance. | Unit 5 |
| Solar noon | — | The moment the Sun is highest in the sky. | Unit 7 |
| Solar zenith angle | θz | Angle between the Sun and straight up. | Unit 7 |
| Solid angle | unit steradian (sr) | Measure of how wide a cone of directions is; a full sphere is 4π sr. | Unit 5 |
| Space radiation | — | High-energy particles from the Sun and cosmic rays that damage semiconductors in orbit. | Unit 6 |
| Specific yield | kWh/kWp | Annual energy per kilowatt of STC rating. | Unit 10 |
| Spectral class / uniformity / temporal stability | — | Simulator grades: spectral match, evenness across the area, steadiness in time. | Unit 7 |
| Spectral irradiance | E_λ; unit W m⁻² nm⁻¹ | Power per square metre per nanometre of wavelength: how sunlight's power is spread across colours. | Unit 4 |
| Spectral mismatch | — | Error caused when a test lamp's spectrum differs from standard sunlight. | Unit 4 |
| Spectral mismatch factor | M | Correction ratio of four spectrum integrals used when calibrating testers. | Unit 8 |
| Spectral radiance | B_λ; W m⁻² sr⁻¹ m⁻¹ | Power per area, per solid angle, per wavelength. | Unit 5 |
| Spectral response | SR; unit A/W | Current produced per watt of light at each wavelength. | Unit 3 |
| Spectral responsivity | SR; unit A/W | Current per watt of light at one wavelength; ideal SR = λ[nm]/1239.84. | Unit 4 |
| Spectrometer | — | Instrument that spreads light into its wavelengths and measures each. | Unit 3 |
| Spectroscope | — | A simple instrument that spreads light into its colours so you can see which wavelengths are present. | Lab A |
| Spectrum | — | The mix of wavelengths (colours) in light and how much power each carries. | Unit 1 |
| Speed of light | c = 2.998 × 10⁸ m/s | Speed of every electromagnetic wave in vacuum. | Unit 3 |
| SQL | Structured Query Language | Standard language for querying databases. | Unit 8 |
| STC | standard test conditions | 1000 W/m² irradiance, AM1.5G spectrum, 25 °C cell temperature: the conditions behind every datasheet rating. | Unit 1 |
| Steady state | — | A condition in which nothing changes over time, so no energy is being stored. | Unit 2 |
| Stefan–Boltzmann constant | σ = 5.670 × 10⁻⁸ W m⁻² K⁻⁴ | The constant in the Stefan–Boltzmann law. | Unit 5 |
| Stefan–Boltzmann law | M = εσT⁴ | Total power radiated per square metre rises with the fourth power of absolute temperature. | Unit 5 |
| Suns (concentration) | — | Multiples of normal sunlight intensity; "500 suns" = 500 times. | Unit 6 |
| Sun simulator | — | Calibrated artificial-sunlight lamp used to test cells and modules. | Unit 3 |
| Sunspot cycle | — | The roughly 11-year rise and fall of the Sun's magnetic activity. | Unit 6 |
| Tandem cell | — | A cell stacking two (or more) absorbers with different band gaps. | Unit 4 |
| Temperature | T; units °C or kelvin (K) | A measure of the average energy of the random jiggling of atoms and molecules. | Unit 2 |
| Temperature coefficient | %/°C | How much a module's output changes per degree of warming (negative for power). | Unit 2 |
| Temperature coefficients | α (I_sc), β (V_oc), γ (P_max), %/°C | Percentage change per °C of current, voltage and power. | Unit 10 |
| Terrestrial | — | At ground level on Earth (as opposed to in space). | Unit 6 |
| Texturing | — | Etching micro-pyramids into the wafer to reduce reflection. | Unit 11 |
| Thermal cycling | — | Repeated swings between hot and cold; a key stress for space and outdoor modules. | Unit 6 |
| Thermal equilibrium | — | A steady state in which an object's temperature is not changing. | Unit 5 |
| Thermalization | — | Loss of a photon's surplus energy above the band gap as heat, within about a picosecond. | Unit 8 |
| Thermal radiation | — | Heat given off as (mostly infrared) light by any warm object. | Unit 2 |
| Thermal voltage | k_BT/q ≈ 25.7 mV at 25 °C | Voltage equivalent of thermal energy per charge. | Unit 10 |
| Thermocouple (K-type probe) | — | A temperature sensor made from a junction of two different metal wires that produces a small temperature-dependent voltage. | Lab B |
| Thermodynamics | — | The physics of heat, temperature and energy conversion. | Unit 2 |
| TOA | top of atmosphere | Just above Earth's atmosphere. | Unit 6 |
| Tool / lot | — | A single process machine / a batch of wafers processed together. | Unit 11 |
| TOPCon | tunnel oxide passivated contact | A mainstream silicon cell design with an ultra-thin oxide layer under the rear contact to reduce losses. | Unit 1 |
| Transmission | — | Light passing straight through a medium. | Unit 7 |
| Trapezoid rule | ΔG = ½(E_i + E_{i+1})(λ_{i+1} − λ_i) | Numerical integration treating each slice as a trapezoid; handles uneven spacing. | Unit 8 |
| TSI | total solar irradiance | The Sun's power per square metre at 1 AU, all wavelengths; ≈1361 W/m². | Unit 6 |
| Ultimate efficiency | — | Efficiency if every above-gap photon delivered exactly the band-gap energy; counts only below-gap and thermalization losses. | Unit 8 |
| Ultraviolet | UV | Light with wavelengths shorter than violet (below ≈380 nm); causes sunburn and degrades plastics. UV-A 315–400 nm, UV-B 280–315 nm. | Unit 3 |
| Uncertainty | ± | The range within which a measured value's true value is believed to lie. | Unit 6 |
| USB | Universal Serial Bus | The standard computer connector, used by digital microscopes and spectrometers. | Starter kit |
| UV-C / UV-B | — | Ultraviolet below 280 nm / 280–315 nm; mostly absorbed by ozone. | Unit 7 |
| UVID | UV-induced degradation | Loss of cell performance caused by ultraviolet light exposure. | Unit 3 |
| Valence band | — | Range of energies of the bonding electrons; full in a cold semiconductor. | Unit 11 |
| Valence electrons | — | Outer electrons of an atom that form bonds (silicon 4, phosphorus 5, boron 3). | Unit 11 |
| V_mp, I_mp | voltage and current at maximum power | The operating point where V × I is largest. | Unit 11 |
| Volt | V | SI unit of voltage: one joule per coulomb. | Unit 1 |
| Voltage | V; unit volt (V); also "potential difference" | The energy given to each unit of charge moving between two points, in joules per coulomb. The "push" behind a current. | Unit 1 |
| Wafer | — | A thin slice (about 0.13 mm thick) of crystalline silicon that becomes one solar cell. | Unit 1 |
| Watt | W | SI unit of power: one joule per second. kW = 1000 W, MW = 10⁶ W, GW = 10⁹ W, TW = 10¹² W. | Unit 1 |
| Watt-peak | Wp | A module's maximum power at standard test conditions. A power, not an energy. | Unit 1 |
| Wavelength | λ (lambda); usually in nm | Distance from one wave crest to the next. Sets the colour of light. | Unit 3 |
| Wave–particle duality | — | Light behaves as a wave when it travels and interferes, and as photons when it is absorbed. | Unit 4 |
| White balance | — | A camera's automatic colour correction; it must be fixed manually for spectral measurements or colours shift. | Lab A |
| Wide-gap cell | — | A cell whose band gap is well above silicon's 1.12 eV. | Unit 7 |
| Wien's displacement law | λ_max = b/T, b = 2.898 × 10⁻³ m·K | A blackbody's peak wavelength is inversely proportional to its absolute temperature. | Unit 5 |
| Work | — | A force pushing something through a distance; work = force × distance. Measured in joules. | Unit 1 |
| Work function | W; unit eV | Minimum energy an electron needs to escape a metal surface. | Unit 4 |
| Xenon arc lamp | — | Lamp with a continuous electric arc through xenon gas; sun-like spectrum, used in simulators. | Unit 5 |
| Zenith / altitude / azimuth | — | Straight up / Sun's angle above horizon (90° − θz) / Sun's compass direction. | Unit 9 |