Solar Glossary

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Schottky barrier: It is a potential barrier created at the metal-semiconductor junction, with rectifying property, to facilitate its use as a diode.

Self -discharge: It is a phenomenon in batteries, wherein the stored battery charge diminishes due to internal chemical reactions, without a connection between the electrodes. This invariably brings down the shelf life of batteries and converts them in a semi-charged state when put in actual use.

Semi-crystalline: Same as モMulti-crystallineヤ.

Semiconductor: Any material with electrical conductivity yet has intermediate capacity of conductivity and falls between the category of an insulator and good conductor. Some semiconductor materials used in PV are silicon, cadmium telluride, gallium arsenide and copper indium dieseline.

Series connection: It is the type of connection, in which the electrical attachment of the components is in a single path (series). That is, the connection of the positive and negative terminals is in a line to give more voltage.

Series regulator: It is a battery charge controller, where a FET, switch or transistor in a series connection with the solar array, regulates the charging current.

Series resistance: The series resistance arises from the resistance of the PV cell material to flow of current, especially through the front surface to the contacts and from resistive contacts. It is a specific problem at high current densities under concentrated light.

Shelf life of battery: Under specific conditions, a battery displays the capacity to retain its maximum charge over a time span, before put to actual use, without self-discharging.

Short-circuit current / ISC: Refers to the current through a solar cell when the voltage across the cell is zero. This is the largest current possibly drawn from solar cell.

Shunt regulator: A charge regulator for the battery in which a parallel -connected switch at the photovoltaic generator controls the charging current. Shorting the generator avoids the battery from overcharging.

Silicon / Si : Refers to the semi-metallic, dark grey, chemical element with atomic no. 14. The most preferred semiconductor material in making PV devices due to its semiconducting properties. It is noticeable in quartz and sand, in the form of oxide. It crystallizes in a cubic lattice with a center face as in a diamond.

Sine wave inverter: Refers to an inverter generating near perfect sine wave output, equivalent to the utility-supplied grid power.

Single crystal material: This can be any material constituting a solitary crystal or several large crystal pieces.

Solar cell: Same as モPhotovoltaic cellヤ.

Solar constant: It is the quantity of solar energy (W/mᄇ) at normal incidence outside the atmosphere at the mean sun-earth distance. It is 1353 Watts / m ᄇ outside the atmosphere and 1000 Watts / m ᄇ at the equatorメs sea level during noon hour.

Solar energy: Radiant light and heat energy harnessed via the sun to produce electricity. The car parked in open gets hot under sun, exhibiting solar energy at work.

Solar noon: When we divide the time between sunrise and sunset by 2, we get solar noon. It divides the daylight hours in equal halves and is different from the 12-hour or 24-hour system.

Solar spectrum: Refers to the total dispersal of radiation through electro-magnetism via the solar source.

Solar thermal electric: It is the production of electricity by focusing the light of the sun to heat the working fluid that causes a turbo generator to operate.

Solar-grade silicon: Less expensive, medium grade silicon used in manufacture of photovoltaic cells.

Split-spectrum cell: Refers to the complex PV device that initially divides the sunlight into spectral portions using optical means. Every portion further leads to a unique solar cell, enhanced for spectrum conversion into electricity. Hence, a general substantial conversion of the incident light into electricity is achievable.

Square wave inverter: It is an inverter with four switches, a Direct Current source and load. Power semiconductors act as switches and can take on a huge current, besides withstanding high rating on the voltage. On-off switch operations take place in the proper order and at prescribed frequency. Even though this device is the easiest to make and cheaper too, it manages extremely low quality power production.

Stand-alone system: It is an electrical power system, energized by solar panels and independent of utility grid. Most systems, which are stand-alone, need batteries or other storage devices.

Stand-off mounting: It is a method of mounting the solar array on any sloping roof, so that the panels are not too far above the roof, positioned at an optimum angle to catch adequate amount of sunrays.

Standard test conditions / STC: The conditions in the standard test specify a temperature requirement of 25ᄚC with irradiance of 1000 Watts per m ᄇ and 1.5- spectrum air mass (AM1.5). These are the normal conditions prescribed for the testing of photovoltaic module. (IEC1215)

State of charge / SOC: Refers to the quantity of electrical charge available in the battery and expressed as percentage difference between fully charged and fully discharged state of battery.

Substrate: It is a material, which underlines the photovoltaic cell.

Sulfating: When the batteries are unused or discharged, they develop a crusty coating of large lead sulfate crystals, instead of normal tiny crystals. This renders the battery unsuitable for recharge.

Superstrate: It is a protective top covering of the PV module, which shields the panels from environmental degradation or impact. At the same time, since it is on top sun side, it facilitates the highest appropriate wavelength transmissions of spectrum generated by the sun.