Glossary of Photovoltaic Terms

Absorptions -Process where solar radiation is retained by a substance and converted into heat energy

Anti-Reflection Coating (ARC)-Consist of a thin layer of dielectric material, with a specially chosen thickness so that interference effects in the coating cause the wave reflected from the anti-reflection coating top surface to be out of phase with the wave reflected from the semiconductor surfaces


Array-Any linked number of Photovoltaic modules electrically connected

Balance of Systems (BOS) -All other parts and components and costs of a photovoltaic system besides the photovoltaic modules.  It includes inverters, mounting structures, labor, civil work, cables, etc.


Band Gap-Energy range between valance and conductive band where no electron state can exists


Blocking Diode -Used to prevent undesired current flow from the battery through the cell when there is no output, or low output, from the solar cell.


Bus Bar – A wider solder coated copper flat wire that carries the current across each row to the junction box


Conduction – Movement of free valence electrons in the conductor material


Conduction Band – Range of electron energies above the valence band where excited electrons can participate in conduction.


Current – Rate of the flow of electrons through an electrical conductor, generally measured in amperes (amps).


Diffusion – Flow of carriers from high concentration regions to of low concentration regions, until the concentration is uniform throughout the material.


Doping – Process of intentionally introducing impurities into a semiconductor to change its electrical properties to cause a change in the electron or hole concentration. In silicon, typical dopants are boron and phosphorous.


Efficiency  – The ratio of power that a solar panel produces as compared to the total amount of energy from the sun falling on the solar panel.


Electrons – A negatively charged particle found in all atoms and acts as the primary carrier of electricity in solids


Full Sun – Amount of power density received at the Earth’s surface at noon on a clear day – 1,000 Watts/square meter²


I-Bus -More aesthetically pleasing rolled and solder coated I shaped Bus Bar that is cut to length of the customer’s specification

Interconnect (Tabbing) Wire -Tinned precision copper flat wire that connects top of one PV cell to the bottom of the next to connect the positive and negative sides of the cells in series to pass electric current


InverterA device that converts electricity from direct current (DC) generated by the solar panel to alternating current (AC) for transmission throughout the grid


Irradiance – Measurement of solar radiation energy received on a given surface area in a given time usually expressed in W/m2.


Kilowatt-HourA measure of electrical energy equivalent to a power consumption of 1,000 watts for 1 hour

Fuel equivalents:

One barrel of crude oil contains roughly 1700 kWh

One ton of coal contains roughly 7500 kWh

One gallon of gasoline contains roughly 37 kWh

One cubic foot of natural gas contains 0.3 kWh

One ton of uranium ore contains 164 million kWh


L-Bus – More aesthetically pleasing rolled and solder coated Bus Bar that is bent 90 degrees to form a L-shape.  Ulbrich’s L-shaped bus ribbon increased solar production by offering customers a pre-formed, ready to install solar ribbon


Light-Capturing Ribbon™ – Grooved interconnect ribbon that increases the efficiency of a solar module by reflecting up to 80% of the photocurrent from light that strikes the ribbon back onto the surface of the solar cell


Load – Products that are powered by electricity (such as a light bulb or water pump)


Majority carrier – In doped material, the carrier with the higher concentration. Electrons are the majority carrier in n-type material. Holes are the majority carrier in p-type material


Minority carrier – In doped material, the carrier with the lower concentration. Electrons are the minority carrier in p-type material. Holes are the minority carrier in n-type material


Open-circuit voltage – Maximum possible voltage across a photovoltaic cell at zero current. Units of volts or millivolts.


Panel  – A packaged collection of photovoltaic solar cells wired together into a single unit.


Photon – particle representing a quantum of light that carries energy proportional to the radiation frequency but has zero rest mass.


Photon Flux – Used in determining the number of electrons which are generated, and hence the current produced from a solar cell. Defined as the number of photons per second per unit area.


Photovoltaic Effect  – The creation of electricity from sunlight by which voltage is produced in a material when photons knock electrons loose from the atoms they strike


PV Interconnect Ribbon/Bus Wire – At Ulbrich all our interconnect and bus bar ribbons are solder coated on all four sides since plating is done after the ribbon is rolled from round wire.  Also, burrs are nonexistent in ribbon/bus wire rolled from round wire


Recombination – The process whereby a free electron falls back into a hole


Semiconductor – A substance with unique properties such that will allow the material to act as both a conductor and an insulator


Series Connection -A wiring configuration of solar cells where positive leads are connected to negative leads to increase voltage


Short-Circuit Current – The maximum current possible when zero voltage and resistance is present


Silicon – The chemical element of atomic number 14 that is the basic material of most beach sand, and is the raw material used to manufacture most photovoltaic cells


Soft Ribbon – Specific solder precision copper PV ribbon that is engineered to achieve the lowest possible yield strength of below 70 N/mm² by more than 25% elongation at fracture of standard interconnect ribbon


Solar Cell – A semiconductor element that converts sunlight directly into electricity


Texturing – A process, usually an etch, to structure the surface of a solar cell to reduce reflectivity.


Thin Film – A layer of semiconductor material, such as copper indium diselenide (CIGS), cadmium telluride (CdTe), or amorphous silicon (a-Si), a few microns or less in thickness, used to make photovoltaic cells


Ultralite Foil – Engineered ultra flat, ripple-free metal substrate and a variety of conductor ribbon/foil used to achieve the optimum conductive solutions for Thin Film solar modules


Valence Band – highest energy band in a semiconductor that can be filled with electrons


Valence Electrons – Electrons that can participate in the formation of bonds with other atoms to form molecules that are found in the outer shell of an atom


Voltage – A measure of the force that pushes electrical current along interconnect wire between solar cells to make an electrical circuit


Watt  – Unit of power where one ampere of current flowing at a potential of one volt produces one watt of power