Glossary
Milk the Sun would like to introduce to you the most frequently used terms and abbreviations relating to solar / PV installations. Should you miss any explanation, please let us know so that we can add it quickly.
Using the following links you can easily navigate to the desired glossary section.
A
ALTERNATING CURRENT
Current whose electric charge reverses its direction periodically; on average, positive and negative charges balance each other out; abbreviated as AC. Opposite of direct current (DC). For historic reasons, most public electricity networks are based on alternating voltage and can therefore not transport direct current. For this reason, energy produced by PV plants has to be transformed into alternating current by inverters so that it can be fed into the grid.
AMORPHOUS MODULE
A special kind of thin-film module which is frequently used for the production of solar cells. The term ‘amorphous’ is derived from the Greek word for ‘shapeless’. Amorphous modules are made from amorphous silicon (a-Si), i.e. the non-crystalline form of silicon, which consists of unorganized silicon atoms. Amorphous silicon is the cheapest basis of solar cells, but it also has the lowest level of efficiency for producing electricity.
AMORPHOUS SILICON (A-SI)
The term ‘amorphous’ is derived from the Greek word for ‘shapeless’. Amorphous silicon (a-Si) is the non-crystalline form of silicon and consists of unorganized silicon atoms.
ANNUAL REPORT
Financial statements and annual reports are imperative for professional administrative support. They have to be well founded in order to accurately inform about a company’s performance at regular intervals.
ANTI-THEFT PROTECTION
Surveillance and deterrent measures for the protection of a thing.
AZIMUTH
The deviation of the solar panel’s position from a north-pointing direction; measured clockwise from north. An azimuth of 0 degrees means that the panel points exactly towards the north; an azimuth of 180 degrees means the panel points towards the south and provides the highest yield. 135 degrees means a south-eastern direction and 225 degrees a south-western direction.
B
BROKER
Facilitator of commercial activities ; intermediary between a buyer and a seller.
BUILDING PERMIT
A permit to build or construct something; depends on country-specific regulations and the particular characteristics of the proposed project.
C
CADMIUM TELLURIDE (CDTE)
A semiconductor; a crystalline compound formed from cadmium and tellurium which is used to produce PV solar cells.
CADMIUM TELLURIDE PV MODULES
Modules which are coated with chemical compounds of cadmium telluride.
CAPITAL INVESTMENT
See (financial) investment
CDTE
See Cadmium telluride
D
DATA PRIVACY STATEMENT
Statement illustrating the protection of customer data. At Milk the Sun all customer data are treated confidentially and encoded. They cannot be accessed by the general public.
DIFFUSE INSOLATION
The solar irradiation (radiation energy) that impinges on a PV module indirectly as a result of scattering due to clouds, fog, haze, dust, or other obstructions in the atmosphere; in the solar industry it is usually measured in watt-hours per m². Opposite of direct insolation.
DIRECT CURRENT (DC)
Electric charge that flows in a constant direction, abbreviated as DC; opposite of alternating current (AC). Solar cells produce direct current. However, for historic reasons, most public electricity networks are based on alternating voltage and can therefore not transport direct current. For this reason, energy produced by PV plants has to be transformed into alternating current by inverters so that it can be fed into the grid.
DIRECT INSOLATION
The solar irradiation (radiation energy) that impinges on a PV module directly, unscattered and unfractured and therefore travels the shortest distance between sun and object; in the solar industry it is usually measured in watts per m². Opposite of diffuse insolation.
DUE DILIGENCE
Due Diligence means the close scrutiny and evaluation prior to a lease, purchase or sale; especially in respect of economic, legal, tax and financial circumstances.
E
EEG
The German Renewable Energy Act (Erneuerbare-Energien-Gesetz, EEG) regulates the feed-in tariffs for renewable energy technologies in Germany.
ELECTRIC ARC
Also referred to as arc discharge. Electric discharge in gases between two conductive electrodes that is continuous (differentiating it from an electric spark). The resulting high temperatures cause the ends of the electrodes to vaporise, producing an ongoing plasma discharge that makes the normally nonconductive gas between the electrodes (such as air) conductive. The resulting electric arc connects the electrodes if they are not too far apart and a required minimum voltage is kept. In electronic systems such as photovoltaic plants electric arcs can be caused by loose cables (i.a.) and result in a short circuit or even fire.
ELECTRIC CURRENT
The flow of electric charge, such as electrons (negative charge) or ions (either negative or positive charge), through a conductive medium.
ENERGY PAYBACK TIME
The time a power generation facility (such as a PV plant) requires to break even with the energy-input of its manufacturing process.
ENERGY TRANSITION
The transition to a sustainable economy by use of renewable energy, energy efficiency and sustainable development. In the wake of the energy transition nuclear, coal and other non-renewable energy sources shall be abolished.
EXCLUSIVITY AGREEMENT
A legally effective agreement of at least one contract partner to exclusively do business with the contract partner(s) regarding a specified deal or issue.
EXPERT’S REPORT
An expert’s report is rendered by an impartial person who is also qualified to do so. It documents deliverables and substantiates accomplishments.
F
FEED-IN TARIFF(S)
National system of monetary compensation paid for electricity generated by renewable energy
FIRE PREVENTION
Ideal fire prevention incorporates local fire regulations, report technological guidelines and standards such as specific features of the respective building.
FIRE RISK
Contrary to rumours claiming otherwise, a solar plant installed with fire prevention measures should not induce an increased fire risk. The risk is comparable to any other electronic plant.
FIT
See feed-in tariff(s)
G
GIGAWATT
A measuring unit of power, abbreviated as GW. 1 GW equals 1 billion watts. Power (W) multiplied by time (h) equals energy (Wh).
GIGAWATT HOUR
A measuring unit of energy, abbreviated as GWh. 1 GWh equals 1 billion watts acting over a period of 1 hour. Energy (Wh) divided by time (h) equals power (W).
GLOBAL INSOLATION
The sum of direct and diffuse insolation (solar radiation energy) that impinges on a horizontal plane along the Earth’s surface, such as a PV module ; it is usually measured in kilowatt hours per m² and year in order to average seasonal variations in insolation.
GREEN FIELD (OPEN SPACE)
Undeveloped and unused land on which e.g. a PV plant can be developed.
(ELECTRICITY) GRID
Public electric power transmission network.
GRID PARITY
Break even point of self-generated and purchased electric energy.
GRID-CONNECTED PV SYSTEM
PV plant functioning like a central electricity generating plant, supplying power to the grid.
GW
See gigawatt
I
INCLINATION ANGLE INSOLATION
The angle between a reference plane and another plane or axis of direction; the inclination angle of a solar panel gives the slope by which it is mounted (with respect to the ground level) and has to be adapted to the respective site and level of insolation.
INSOLATION
The solar radiation incident on a solar panel over time, relative to its area; it is usually expressed in watt-hours per m². Plays an important role in the determination of the optimal inclination angle of PV modules and the profitability of a PV system. Insolation (Wh/m²) divided by time (h) equals irradiance (W/m²).
INVERTER
Component of a PV plant that converts direct current (DC) into alternating current (AC) that can be fed into the grid.
(FINANCIAL) INVESTMENT
Commitment of financial means to an asset with expected capital growth upon thorough analysis.
INVESTMENT OPPORTUNITY
Possibility or proposal to commit financial means to an asset.
INVESTOR
An investor commits financial means to securities, tangible assets (e.g. photovoltaics), real estate or the like with the intention of capital gain.
IRRADIANCE
Irradiance measures the solar power incident on a solar panel, relative to its area; it is measured in watts per m². Irradiance (W/m²) multiplied by time (h) equals insolation (Wh/m²).
K
KILOWATT
A measuring unit of power, abbreviated as kW. 1 kW equals 1,000 watts. Power (W) multiplied by time (h) equals energy (Wh).
KILOWATT HOUR
A measuring unit of energy, abbreviated as kWh. A kWh is the measure for 1,000 watts acting over a period of 1 hour; 1 kWh equals 3,600 kilojoules (kJ). Energy (Wh) divided by time equals power (W).
KW
See kilowatt
KWH
See kilowatt hour
KWP
Abbreviation of kilowatt-peak. Measure of the nominal power of a photovoltaic solar energy plant under standard laboratory conditions. Using kWp as a common measure in the PV industry is convenient because a PV system’s actual power varies with the intensity of sunshine and other conditions.
L
LAND OWNER
Owner of a green field; see green field (open space).
LEASE
A contractural arrangement committing the lessee (user) to pay the lessor (owner) for using an asset as well as potential proceeds resulting from it.
LEASING A ROOFTOP
A vacant / unused rooftop can be leased to an investor to produce solar energy. This way the lessor can obtain additional earnings over a period of 20-35 years.
LEGAL ADVICE
A professional legal counsel supervises all kinds of legal concerns of a company. Applied to the photovoltaics industry this includes knowledge of feed-in tariffs, fiscal matters, political developments and contractual commitments among others.
LEGISLATION
The utilisation and expansion of PV are regulated by laws which inter alia determine feed-in tariffs.
LETTING A ROOFTOP
See leasing a rooftop
LIGHTNING PROTECTION
Measures protecting against strokes of lightning that are attached to a building. Usually, a solar plant does not increase the risk of lightning strokes. In case the building already has lightning protection the PV plant can be installed without additional arrangements. Subsequent mounting of lightning protection is also possible.
LIQUIDITY MANAGEMENT
Organising the money supply and credit availability of banks based on financial theory and macroeconomic aspects, especially with respect to price stability.
LIQUIDITY PLANNING
Ensuring solvency. Can be prepared in the course of setting up a financial plan; shows incoming and outgoing cash flows.
M
MAINTENANCE
Regular upkeep and inspection of a photovoltaic plant ensures stable production.
MEGAWATT
A measuring unit of power, abbreviated as MW. 1 MW equals 1,000,000 watts. Power (W) multiplied by time (h) equals energy (Wh).
MEGAWATT HOUR
A measuring unit of energy, abbreviated as MWh. A MWh is the measure for 1,000,000 watts acting over a period of 1 hour. Energy (Wh) divided by time (h) equals power (W).
MICROMORPH
Concept to increase the efficiency of solar cells by installing an absorber for blue light in the first step and red light in a second step.
MONOCRYSTALLINE SOLAR PANEL
Is cut from a single-crystal ingot, usually made of silicon. The cylindrical ingot is sliced with a wafer saw into (usually square) wafers that form the solar cells used in solar panels. Monocrystalline solar cells achieve a relatively high level of efficiency, but also entail high manufacturing costs, especially due to material waste during wafer production.
MONOCRYSTALLINE SOLID
Also referred to as single crystal. Material whose crystal lattice is continuous and unbroken to the edges of the sample and does not have grain boundaries.
MW
See megawatt
N
NETWORK OPERATOR
Operator of the power grid.
NEW PLANTS
Plants that have been mounted for the first time and recently been connected to the grid. New plants are traded on the PV primary market.
NON-DISCLOSURE AGREEMENT
Abbreviated as NDA; also known as a confidentiality agreement (CA), or secrecy agreement. A legal contract between at least two parties which outlines common confidential material or information the access to which by third parties shall be restricted.
O
OFF-GRID SOLAR SYSTEM
A PV system that is not attached to the public grid. The energy produced is either used directly on the spot or stored in batteries.
OPERATING COMPANY
Operating companies finance, plan and operate plants. The generated profits go to the operating company, also referred to as special purpose vehicle (SPV).
OPERATING PLANT
A productive PV plant that has already been installed, connected to the grid and is producing electricity.
OPERATIONAL MANAGEMENT
The operational management is performed by professionals with a commercial and/or economic background that administer a company or an investment.
OPERATOR
The operator uses the solar plant to generate electricity; the operator can be, but does not have to be, the owner of the land or rooftop.
ORIENTATION
A solar panel’s orientation describes its slope, the angle of the panel. A distinction is made between azimuth and tilt angle.
OVERHEATING
Technical equipment can overheat. The same goes for the inverters connected to PV plants. To prevent inverters from overheating overvoltage protection devices such as the direct current (DC) circuit breaker can be attached to the PV system. In case of overheating it separates the inverter from the PV panels and therefore minimises the risk of electric arcs which could seriously damage the plant.
P
(SOLAR) PANEL
Also referred to as solar module. A component of a PV plant.
PERFORMANCE RATIO
A key performance indicator frequently used in the photovoltaics industry to describe the quality of a solar farm which is defined as the ratio between real gain and target gain.
PHIL
Acronym for ‘Photovoltaik-Hilfe’ (German for ‘photovoltaic support’). Online planning software for calculating shading and profitability of PV systems.
PHOTOVOLTAIC MARKET
Space for trade and business in the context of the photovoltaic industry.
PHOTOVOLTAIC MODULE
Also referred to as photovoltaic panel. A packaged, connected assembly of PV cells. Comes with or without frame.
PHOTOVOLTAIC SYSTEM
Solar installation. An array of solar panels used to convert sunlight into electricity.
PHOTOVOLTAICS
The term photovoltaics is a composite of the Greek word ‘Phos’ meaning ‘light’ and ‘voltage’, named after Italian physicist Alessandro Volta. As its composites suggest, photovoltatics means the conversion of light into electric energy.
PLANT MANAGEMENT
Professional monitoring and maintenance of a technical plant that guarantees safe production.
PLANT OWNER INSOLATION
The legal owner of a PV power plant.
POLYCRYSTALLINE SOLAR PANEL
The solar cells used for polycrystalline solar panels are cut from square polycrystalline ingots, usually made of silicon. They are less efficient than single crystal silicon cells, but also less expensive. Therefore polycrystalline solar panels are often claimed to have a more desirable price-performance ratio than monocrystalline modules.
POLYCRYSTALLINE SOLID
Material composed of many crystallites of varying size and orientation.
(ELECTRIC) POWER
Power is energy per unit of time; more generally, it is the rate of doing work. Instead of using a PV plant’s power as a characteristic, its nominal power, measured in kWp, is generally preferred in the industry, since it is a standard measure.
POWER SUPPLY
The supply of electric current for end-consumers by connection to the public electricity grid.
PRIMARY MARKET
‘Conventional’ market in which (new) goods, services and rights are traded (comparable to the primary market of financial capital, in which new stock or bond issues are sold to investors by underwriting). Applied to the solar industry, in the PV primary market (new) project rights and newly installed plants are sold.
PRIVATE CONSUMPTION
Private (energy) consumption means that the energy generated by a PV plant is consumed on site instead of being fed into the grid; private consumption is generally beneficial for users if the respective feed-in tariff is lower than their individual electricity price.
PROJECT DEVELOPER
In the photovoltaics industry a project developer is the market player who brings an undeveloped and unused area to a ready-to-build status (project right) for a solar installation.
PROJECT RIGHTS
A contractually secured legal right of use, e.g. to a rooftop or green field for building a PV system thereon.
PROJECT SIZE
Size of a project.
PROPRIETOR
The proprietor of a thing is the person who wields the power of disposition over it. This includes the observance of rights and obligations arising thereby.
PV
Abbreviation of photovoltaic(s), see photovoltaics.
PV ANTI-THEFT PROTECTION
Anti-theft protection that is specifically tailored to the requirements of PV systems.
PV GENERATOR
The total of all PV strings in a PV system which are electrically interconnected.
PV INSURANCE
Insurances that are specifically designed for PV systems. There are two main kinds: PV insurances (also referred to as ‘solar insurance’) and PV liability insurance (also referred to as ‘operator liability insurance’).
PV MARKET
See photovoltaic market.
PV SECONDARY MARKET
Grey market. A secondary market is a market for trading goods that have been sold at least once before and for claims resulting from effective contracts during their term (comparable to the secondary market of financial capital, in which existing securities are sold and bought among investors or traders, usually on a securities exchange or over-the-counter). Applied to the solar industry, in the secondary market already installed and producing plants are traded.
PV SERVICES
All kinds of services relating to photovoltaics including PV insurance, legal counsel as well as maintenance and repair.
PV SYSTEM
See photovoltaic system.
PVCALC
Online tool that allows to calculate the return on investment (ROI) of PV solar energy projects.
PV-SOC
Acronym for Photovoltaic-Security Operations Center. PV-SOC is an all-round anti-theft protection service package specifically designed for the requirements of photovoltaic plants.
R
REMOTE MONITORING
An automated data logger monitors the proper functioning of a technological facility (e.g. a PV plant) to reveal potential malfunctioning.
RENEWABLE ENERGIES
All energy sources that are inexhaustable since they naturally replenish. These include the utilization of water, sun, wind, biomass and geothermics.
ROOF AREA
The total area of a rooftop.
ROOFMOUNTED SYSTEM
A PV system that is installed on a sloping or flat roof.
ROOFTOP OWNER
The owner of a rooftop is the person who actually holds it. The owner can be but does not have to be the proprietor who possesses the object legally.
S
SECONDARY MARKET
SECONDARY MODULE MARKET
Market for trading pre-owned solar panels
SHADING
Trees, neighbouring houses or the like impair the solar irradiance on a solar panel and thereby reduce the yield of a solar plant.
SOLAR
Latin for ‘of or relating to the Sun’.
SOLAR CELL
Solar cells are a fundamental element within photovoltaics. When exposed to light they produce an electric current (voltage) by use of the photovoltaic effect.
SOLAR ELECTRICITY
Electricity generated by a PV plant or alternative solar technology.
SOLAR ENERGY
Electric energy and heat generated in various ways by the help of solar irradiance.
SOLAR INDUSTRY
Economic sector dealing with photovoltaics.
SOLAR MARKET
See photovoltaic market.
SOLAR PARK / SOLAR FARM
A ground mounted PV system that has been erected on a green field (open space); usually solar parks cover an area of at least 3 hectares and therefore generate a relatively high yield. Thus they generally receive lower feed-in tariffs than roof- and façade-mounted systems.
SOLAR POWER
See solar energy
SOLAR SYSTEM
See photovoltaic system
SOLAR THERMAL ENERGY
Conversion of solar irradiance into thermal energy, meaning the generation of heat.
SPV
Acronym for ‘Special Purpose Vehicle’. See operating company
SUBSIDY
State assisstance paid to businesses or sectors. In the case of photovoltaics subsidies usually mean feed-in tariffs.
SUSTAINABILITY
Used to stand for a longer-lasting impact. Nowadays it chiefly describes the use of regenerative systems such as power generation based on renewable resources.
T
THIN-FILM
A thin film is a solid substance layer ranging from fractions of a nanometer to several micrometers in thickness. It often possesses physical properties that differ from those of the materials it covers, such us electrical conductivity.
THIN-FILM MODULES
These are modules with a coated surface. Their physical properties and energy conversion efficiency vary depending on the respective coating used. Special kinds of thin-film modules are amorphous modules and Cadmium telluride (CdTe) modules.
TO LEASE
See lease
U
UNUSED AREA
See green field (open space)
W
W
See watt
WAFER
Photovoltaic wafers are slices of mono- or poly-crystal ingots, usually made of silicon. The ingot is cut with a wafer saw into (usually square) wafers that form the solar cells used in PV panels.
WARRANTY
Certificate of minimum durability. In general manufacturers of PV modules guarantee a lifetime of at least 20 years. However, there are estimates that range up to 35 years.
WATT
A measuring unit of power, abbreviated as W. Named after Scottish inventor James Watt. Power (W) multiplied by time (h) equals energy (Wh).
WATT-HOUR
A measuring unit of energy, abbreviated as Wh. 1 watt acting over a period of 1 hour; 1 Wh equals 3,600 Joules (J). Energy (Wh) divided by time (h) equals power (W).
Y
YIELD
The yield of a PV plant measures the energy that it produces with a given nominal power, measured in watt-peak (Wp), in a certain amount of time. It is measured in watt hours (Wh) and determines the value and profitability of a solarfarm.