Solar investment advisory

Solar energy glossary

Technology glossary :

Alternating current (AC) : electric current whose direction reverses cyclically, as opposed to direct current (DC), whose direction remains constant. The usual waveform of an AC power circuit is a sine wave, as this results in the most efficient transmission of energy. However in certain applications different waveforms are used, such as triangular or square waves. Used generically, AC refers to the form in which electricity is delivered to businesses and residences. (Source: Wikipedia)

Amorphous solar panel : the cells which constitute these panels are made up of silicon atoms organized in a thin homogeneous layer instead of being out of crystals. The advantage is to allow the manufacture of flexible panels, easy to produce and thus cheaper. But their output is weak, about 7%. One can also apply very fine layers to panes, metal or flexible plastic. Some roofs of large retailers buildings are covered with such panels. They are also used for watches and electronic calculators. They function even under conditions of low radiation.

Continuous current : with the rise of semiconductor technology, continuous current (also referred to as DC or Direct Current) has become widely established. This is especially true in low-voltage applications and for most electronic circuits. Because conversion from alternating current (AC) to DC generates significant losses, the basis for the predominance of alternating current is being altered. The ongoing development of decentralized electric power production, through renewable sources system integrated into buildings (predominantly DC native sources like photovoltaic panels) continues. AC predominates when it comes to electricity transport but there exist a number of high to very-high-voltage DC transmission lines throughout the world. A recent study demonstrated that a typical office building partially supplied by photovoltaic arrays consumes 15 per cent more electricity due to conversion losses. Direct use of DC production on the other hand consumes 15 per cent less electricity for an overall savings. Gains are not easily quantifiable. But getting rid of transportation and conversion loses, utilizing local DC generation as alternative to centralized production, and pushing users/manufacturers to use very-low consumption appliances, are just a few of the advantages of DC. (Source: Leonardo Energy)

Effect of mask : shades on a solar panel caused by obstacles such as buildings,  vegetation or relief for example. These obstacles should not exceed an angle higher than 20°.

Gigawatt (GW) : 1000 Megawatts or 1 billion watts.

Inverter : system which transforms continuous current produced by  photovoltaic panels into alternating current which corresponds to public transmission line.

HVDC : A High Voltage Direct Current electric power transmission system uses direct current for the bulk transmission of electrical power, in contrast with the more common alternating current systems. For long-distance distribution, HVDC systems are less expensive and suffer lower electrical losses. For shorter distances, the higher cost of DC conversion equipment compared to an AC system may be warranted where other benefits of direct current links are useful. Furthermore, its footprint on the environment is lower unlike conventional aerial electric cables.

Kilowatt (kW) : equal to one thousand watts. The watt (symbol: W) is the unit of power, equal to one joule of energy per second. It measures a rate of energy conversion.

Kilowatt-hour (kWh) : quantity of energy corresponding to thousand watts of power delivered in one hour.

Loss of efficiency connected to the temperature : the heat acts on the solar panels by making them less efficient. The Wp of the manufacturer is based on a temperature of the cells of 25 degrees C°. On average 0,50 % is lost for each additional degree.

Megawatt (MW) : 1000 KW or 1 million watts.

Moncrystalline solar panel : The most efficient and expensive solar panels are made with Monocrystalline cells. These solar cells use very pure silicon and involve a complicated crystal growth process. Long silicon rods are produced which are cut into slices of .2 to .4 mm thick discs or wafers which are then processed into individual cells that are wired together in the solar panel. (Source: www.freesunpower.com). But it is the technology which offers the best output, about 15% to 17%.

Photovoltaic cell : the key element which makes it possible to capture and convert solar energy into electricity. A module is formed by of a series of coupled cells.

Photovoltaic effect : discovered in 1839 by Edmond Becquerel, a French experimental physicist. Direct conversion of sunlight into electricity thanks to the use of photovoltaic cells which produce a continuous current when they are struck by photons or “packets of energy” produced by the sun. These cells use semiconductor materials like silicon.

PV energy or photovoltaic energy : corresponds to the energy of the photons contained in the sunlight which is transformed directly into electricity  thanks to solar panel cells. The cells are manufactured with semiconductor materials. They have the properties to provide the voltage needed to drive the current through an external load as a long as they are exposed to sunlight.

Photovoltaic panel : inter-connected photovoltaic cells assembled in a tight unit facilitating its transport and its installation in module fields.

Polycrystalline solar panel : Often called Multi-crystalline, solar panels made with Polycrystalline cells are a little less expensive and slightly less efficient than Monocrystalline cells because the cells are not grown in single crystals but in a large block of many crystals. This is what gives them that striking shattered glass appearance. Like Monocrystalline cells, they are also then sliced into wafers to produce the individual cells that make up the solar panel. (Source: www.freesunpower.com) Their output is also lower, about 12% but it is used for the electric production because of their optimum quality-price ratio. They are designed to last at least 25 years.

Resilience of photovoltaic panels : PV panels are resilient to bad weather thanks to protection of the outside face with toughened glass which bears very difficult weather conditions as abrupt changes in temperature, abrasion, ice or impacts of hail. To be cleared, a panel is submitted to standard test which consists in throwing a ball of ice of given dimensions, by means of a pneumatic device, in the center of the glass, or in dropping a ball of steel from 1 meter height. The toughened glass benefits from anti-reflection coat which increases the efficiency of the cell.

Solar energy for a specific geographical area : to assess the potential return on photovoltaic panels in a specific place, use an on-line free software proposed by the European Commission at the following address :
http://re.jrc.ec.europa.eu/pvgis/apps/pvest.php?lang=en&map=europe

Solar radiation : quantity and intensity of light received by an area. The power resulting from a sensor is proportional to the sunlight intensity.

Solar Tracker : automatic mobile system which allows to follow the orientation of the sun under a constant angle of incidence of 90° that permanently optimizes the output and improves the quantity of received solar energy.

Wafer : thin slice of semiconductor material, such as a silicon crystal, used in the fabrication of integrated circuit and other microdevices. The wafer serves as the substrate for microelectronic devices built in and over the wafer and undergoes many microfabrication process steps such as doping or ion implantation, etching, deposition of various materials, and photolithographic patterning. Several types of solar cells are made from such wafers. A solar wafer is a circular solar cell made from the entire wafer (rather than cutting into smaller rectangular solar cells).

Watt-peak (Wp) : measures the power of a photovoltaic sensor. It is the power maximum delivered under optimum conditions of sunlight and temperature. This measurement makes it possible to compare between them photovoltaic materials.