Go Solar Power For Homes Glossary of Terms – O to Q

Posted on 2009 under Glossary of Terms | No Comment

22 Feb

Ohm = The unit of resistance to the flow of an electric current.

One-axis tracking = A system capable of rotating about one axis.

Open-Circuit Voltage (VOC) = The largest voltage possible across a photovoltaic solar panel; the voltage across the solar panel in sunlight when no current is flowing.

Orientation = The direction that a solar panel faces. Establish orientation by finding two components – the tilt angle (the angle the solar panel makes from the horizontal) and the aspect angle (the angle the solar panel makes from North).

PV = Abbreviation for photovoltaic. (See below)

Panel = A group of solar cells, also known as a module.

Parallel connection = A way of connecting two or more devices that produce electricity (for example, modules or PV cells) by connecting negative leads together and also positive leads together. This style of configuration increases the flow of electrical current.

Passive solar home = A house that utilizes part of the building, such as a room or another part of the building, as a solar collector. The alternative is active home solar (see above).

Peak load = The largest amount, or maximum load, of electricity being used at any one point during a given period of time, normally over the course of one full day.

Peak watt = A unit used to rate the performance of solar cells, modules, or solar arrays; representing the maximum rated output of a photovoltaic device, stated in watts and established under standardized test conditions. Typical rating conditions are 0.645 watts per square inch, or 1,000 watts per square meter, of sunlight, 68 degrees F (20 degrees C), ambient air temperature and a wind speed of 6.2 x 10-3 mi/s (1 m/s).

Photon = A “packet” or particle of light energy acting as an individual unit of energy.

Photovoltaic = the process of directly converting light into electricity. Photo is Greek for “light”. Voltaic means “electric”.

Photovoltaic (PV) array = An interconnected system of photovoltaic modules that are all linked together, functioning as a single electricity-producing unit. In smaller systems, a PV array may consist of just one single module.

Photovoltaic (PV) cell = The smallest semiconductor element within a PV module, the basic unit of a solar panel that collects energy from the sun. Mostly made from silicon, they convert light into electrical energy (dc voltage and current).

Photovoltaic (PV) effect = The basic physical process when a solar cell converts sunlight into electricity. Sunlight is made up of packets of solar energy known as photons. The PV Effect has taken place when photons (the “particles” in a beam of sunlight) knock electrons loose from the atoms they strike. When photons strike a Photovoltaic cell some are absorbed producing electricity. The energy from the photons is transformed into an electron in an atom within the solar cell. As an electron, the energy can now escape the atom and flow as current in an electrical circuit. When this effect is passed into a semiconductor, electrons flow in one direction across a junction which sets up a voltage. Add circuitry to all this and current will naturally flow. Thereby electrical power is made available. (Here endeth the physics lesson!)

Photovoltaic (PV) efficiency = The ratio of electrical energy generated by a cell at any instant, to the power of the sunlight that is striking the cell. Commercially available cells average out about 9 percent to 14 percent.

Photovoltaic (PV) generator = The total of all electrically interconnected PV strings of a PV power supply system.

Photovoltaic (PV) module = The basic solar panel, the assembly of solar cells and ancillary parts, interconnections, terminals, (and protective devices such as diodes) that are protected from the environment by their layers of glass, plastic and metal frame. They re designed to generate dc electrical power from sunlight. They collect energy from the sun.

Photovoltaic (PV) panel = Also known as a PV module, this is a physically connected collection of modules or a laminate string of modules used to achieve a pre-stated level of voltage or current.

Photovoltaic system = All the various parts needed to convert the light from the sun into electricity we can use. This will include the array and balance of system components. In addition to converting sunlight into electricity, the PV system collects the residual heat energy, gathers everything up and delivers both heat and electricity to us in usable form. A PV system might also be known as a ‘total energy system’.

Polycrystalline = see Multicrystalline.

Polycrystalline Solar Cells = Polycrystalline solar cells are very durable solar panels that are generally blue in color. These panels ensure that the individual crystals they consist of are made visible from many angles. Generally, the cells are square, thereby offering the most efficient power production from any solar panel size. The angle the panel is set at is not as important with polycrystalline solar cells as these cells can make use of light from many different angles. They are more efficient in low light and perform well in high temperatures.

Power conditioning equipment = A collective term for battery charge regulator, inverter, converter and blocking diode, this is the electrical equipment that is used to convert power from a photovoltaic array into a form suitable for subsequent use.

Power factor = The ratio of the average power and the apparent volt-amperes.

Qualification test = The official test, subject to a list of pre-defined requirements, that is applied to a selected set of PV modules. This test involves the application of defined mechanical, electrical or thermal stress in a prescribed manner and amount. If the module passes the test, it becomes qualified.

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Info via: solar4power.com, homesolarpowersystems.org, sunwize.com and sunrunhome.com

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