photon energy group


A list of terminology from our website and the solar energy industry.


Alternating current. Electricity with an ongoing and often periodic change of the current direction. It can be transformed into different tensions by a transformer. 


asset management

A service that includes tasks like controlling, monitoring of contracts or the organisation of general meetings. 


back surface field

A layer of silicon solar cells, which reflect electro. 



The ability to transport energy in a space. 



The chemical abbreviation for crystalline silicon. 



A decrease in the degree of efficiency of modules, which is a decrease in performance over time. 


degree of efficiency

The ratio of useful power to potentially existing power. 



The full mixing of substances due to the distribution of particles. The particles move from areas with a high concentration to areas with a low concentration. 



Direct current. Electricity which does not change its direction. It is constant in time. 


direct radiation

The share of solar radiation, that strikes the earth's surface or PV module unscattered and directly.


electric field

An omnipresent physical field created by the power that electrically charged particles have in the space around them, allowing the transfer of electrical energy. 



The output or transmission of noxious substances. 


emission factor

The relation of the masses of an emitted substance to the inserted masses of a raw material. 


emissions savings

The avoidance or reduction of CO2 output. 


energetic amortisation

The length of time that a PV system needs to run until the power needed to produce the modules is produced. 



Engineering, procurement and construction. The usual form of project execution and contract management in the building industry. The contractor is the EPC. The EPC fulfils all necessary performances to deliver a turnkey plant to the client. 


feasibility study

A study into the feasibility of a project. Solutions are analysed, risks are identified and chances of success are estimated to determine through what resources and in how long the desired results of the project results can be achieved. 


global radiation

All the radiation that strikes a surface, including both direct and indirect radiation. 



Gigawatt hour. A unit of energy equal to one GW of power sustained for one hour. 


hot spot

The temperature fluctuations within a module. This means in specific that there is an overheating of certain sections of the module which can be caused by e.g. unequal incidence of light, shading or a manufacturing defect. 


inclination angle

The angle between a PV system and a horizontal surface. The optimal inclination angle depends on the latitude on which the system is installed. 


integrated series circuitry

Used during the manufacturing of large-area modules with thin-film technology. Thereby, the solar cell is cut into strips and afterwards the front of a cell is connected with the back of the neighboring cell. 



A unit that transforms direct current to alternating current. 


island system

An independent energy supply system without grid connection. The produced electricity is consumed by the producers and not fed in. 



Kilowatt hour. A unit of energy equal to one kW of power sustained for one hour. 



Kilowatt peak. The maximum power output of a photovoltaic system measured under Standard Test Conditions. 


large off-grid power

A large-scale power source, separate from the local energy grid. It massively reduces the volatile fuel and logistic costs of electricity generation. This hybrid solution combines photovoltaic solar arrays with batteries and back-up generators to ensure a stable and reliable power supply on demand. Systems are highly scalable starting from 30 to 300 kWp. 


large on-grid power

A highly scalable system that covers up to 30% of daily peak demand power without impacting power quality and saves significantly on peak-time power costs. 


maximum power point

The working point of a solar cell at which the maximum performance, which means the maximum product of electricity and voltage, is reached. This point is not a constant one and depends on certain factors. 


micro off-grid power

A means of generating power where it is needed, separate from the grid. A fully integrated hybrid system includes a battery and a generator backup for up to 30 kWp. 


micro on-grid power

A way to reduce overall power costs with an independent power supply. Power storage allows you to use as much solar power as available while connection to the grid will provide supplemental power as needed. 



Solar cells that transform sunlight directly into electrical energy. 


module efficiency

The relationship between the output of electrical power of a module and the irradiated performance. The higher the module efficiency, the higher the output of the same surface area. 


monocrystalline modules

Modules with a homogenous orientated crystalline structure, through which higher efficiency than that of polycrystalline modules can be reached. Because of the high production effort, monocrystalline modules are expensive. 


MPP tracking

MPP tracking forms the basis for operating a PV system at its maximum power point all of the time. For this purpose, the voltage is readjusted. The needed MPP tracker is part of an inverter or a regulator. 



Megawatt peak. The maximum power output electric power of a photovoltaic system measured under Standard Test Conditions. 


payback period

The payback period is the period of time during which the capital bound in an investment flows back. 


performance ratio

The share of electricity which is available in real terms. 


photovoltaic power plant

A power plant consisting of solar modules, through which solar radiation is directly transformed into electrical energy. 


polycrystalline modules

Modules which consist of inhomogeneously arranged crystals and have a lower efficiency than monocrystalline modules, but are less expensive because of a simpler manufacturing process. 


Pty. Ltd.

Proprietary Limited. A company that is limited by shares, where shareholders are afforded more protection when it comes to the level of liability that they face for company debts. 



Photovoltaic. The conversion of light to energy. 


rated output

The maximum output of a solar cell, determined under standard test conditions. It is expressed in Wp (watt peak). 


rating of a plant

The rating of a plant helps to determine the quality and the default risk of a PV system. 


reflection losses

The amount of solar radiation that is reflected by the surface of a solar cell and cannot be used to produce electric energy. 



Producers of renewable electrical energy get a remuneration payed by public utility companies for the feed-in into the electricity grid. The remuneration is regulated by the Erneuerbare-Energien-Gesetz. 



Dismantling generally describes the uninstalling of the PV system und the restoration of the original state of the roof top or green field. Usually, the removed defect and/or used modules are taken back by the installing company and then they are given to the manufacturer. The recycled modules can be used to generate new modules. 


revenue enhancement

Increasing the output of electrical power generated by a PV plant. 



The partial or complete usage of the generated electricity by the owner, which will be remunerated separately in order to create a financial incentive. 



Società a Responsabilità Limitata. A european legal form of society. 



Společnost s ručením omezeným. The Czech name for a private limited company. 


Standard Test Conditions

An international standard to determine the rated output of modules in an objective way, allowing different modules to be evaluated and compared independently. 


sunshine hours

The number of hours per day during which direct sunlight exists. 


technical acceptance

The inspection of the completed PV system according to the fulfilment of certain minimum requirements regarding special quality and test regulations. 


technical due diligence

A risk assessment, normally made by a buyer when he or she buys shareholdings or real estate or in case of an initial public offering. Due-diligence examinations analyse strengths and weaknesses of the object as well as corresponding risks. 


thin-film modules

Modules that have minimal thickness and are inexpensive to produce. They are flexible and light. Their degree of efficiency is lower than the one of other modules. 


utility-scale power

The integration of solar power to diversify power sources, boost weak spots in the grid, cover transmission losses and boost production in summer peak time. 



A thin circular or square disc. These discs are made out of mono- or polycrystalline blanks and they are the base plate for electronic components. 


yield report

A detailed report of the long-term rate of return, which a PV system can generate at its site. It supports the financing commitment of a bank.