Definition of common solar PV terms

GREEN Solar Glossary

When people talk about solar power, they use a lot of technical terms. The GREEN Solar Glossary has been created to help you understand exactly what our trainers and other installation pros are talking about when it comes to PV solar.

Our glossary also includes French terms to assist French-speaking students in West Africa who are completing an online eLearning course developed by GREEN as part of the project. You can read more about this project here >>

AC (alternating current) (Français: CA (courant alternatif))
Form of electrical current which reverses its direction regulary within a certain interval. In households and most national electricity grids the electricity is AC.

activation voltage(s) (Français: tension(s) d’activation)
A voltage, at which the charge controller will protect the batteries.

air mass (sometimes called air mass ratio) (Français: masse d’air (parfois appelée rapport de masse d’air))
Defines the direct path length the solar radiation travels thorugh the atmosphere. It is expressed as a ratio to the upwards path length.

albedo (Français: albédo)
The fraction of light that is reflected by a body or surface. It is commonly used in astronomy to describe the reflective properties of planets, satellites, and asteroids.

ambient temperature (Français: température ambiante)
The surrounding temperature.

ampere (amp) (Français: ampère (amp))
A unit of electrical current. It expresses the amount of the electrons flow.

ampere-hour (Ah/AH) (Français: ampère-heure (Ah))
The amount of current flowing over a one hour period of time. Often used to measure battery capacity of lead-acid batteries.

angle of incidence (Français: angle d’incidence)
The angle the sun creates with a perpendicular line of the panel, when hitting named panel.

anti-reflection coating (Français: couche antiréfléchissante)
A layer applied to a glass (like the one of a solar panel) which reduces reflection, therefore increasing transmission.

array (PV array) (Français: Champ PV (rangées de modules PV))
An amount of solar panels connected to one another, becoming one elictricity producing unit. Often mounted to one structure.

array current (Français: Intensité de rangées ou du champ PV)
The amount of current and array produces, when it is exposed to sunlight.

array operating voltage (Français: tension de fonctionnement du champ PV ou de la rangée de modules PV)
The voltage produced by a to sunlight exposed array, when it is connected to a load.

autonomous system (stand alone system) (Français: système autonome)
A solar system, which is not connected to the electrical grid. It often requires a battery storage, but it is not mandatory.

azimuth angle (Français: angle d’azimut ou l’Azimut)
The angle between true south and the point on the horizon directly below the sun. It is used to describe the orientation of PV sytems. 0° is orientation towards South and 180° towards North.

balance of system (Français: équilibre du système)
All components and costs other than the PV Modules including not only the cost of the components itself, but also other costs like labour etc.

base load (Français: charge de base)
The average amount of electrical power, which is needed to supply the loads, given by the electrical source(s).

battery (Français: batterie)
Electrochemical storing units, connected in series and or parallel in order to match the required output of current and voltage.

battery available capacity (Français: capacité disponible de la batterie)
The withdrawable amount of ampere hours in consideration of facotrs like discharge rate, age, state of charge etc.

battery capacity (Français: capacité de la batterie)
The maximum ampere hours or kilowatt-hours deliverable to a load from a battery under certain conditions.

battery cycle life (Français: durée de vie de la batterie)
The amount of discharges a battery can deliver under a certain depth of discharge, before it will not meet the promised amount of ampere hours.

battery energy capacity (Français: stockage de l’énergie de la batterie)
The total amount of Watt hours that can be withdrawn from a battery under consideration of factors like age, temperature, rate of discharge etc.

battery energy storage (Français: stockage de l’énergie de la batterie)
The total of all electrochemical batteries in a storage system with their available energy.

battery life (Français: durée de vie de la batterie)
The amount of cycles or time in years a battery can deliver the specified performance.

bypass diode (Français: diode bypass ou de dérivation)
Bypass diodes are used in PV modules to allow current to pass around shaded areas of a module and thereby reduce the voltage losses through the module.

capacity (C) (Français: capacité (C))
Capacity is an indication of how much energy can be stored by the battery. Expressed in either Ah or kWh

charge (Français: charge)
When a battery is receiving electrical energy from external d.c. source it is said to be the charging. There are four stages to battery charging: bulk, absorb, float and equalisation.

charge controller (Français: contrôleur de charge ou régulateur)
A charge controller or charge regulator regulates the voltage and current coming from the solar panels going to the battery/ies to protect them against overcharging.

conductor (Français: conducteur)
An object or type of material that allows the flow of charge (electric current) in one or more directions. Materials made of metal are common electrical conductors.

conversion efficiency (Français: rendement de conversion)
Defined as the ratio of energy output from the solar cell to input energy from the sun. Most solar panels provide an energy efficiency rating between 11 and 15 percent, which is the percentage of solar energy that is being converted into useable solar panels provide an energy efficiency rating between 11 and 15 percent, which is the percentage of solar energy that is being converted into useable electricity.

crystalline silicon (Français: silicium cristallin)
Crystalline silicon – either polycrystalline silicon or monocrystalline silicon – is the dominant semiconducting material used in photovoltaic technology for the production of solar cells.

current (Français: courant)
Electric current is the movement of electrons through a wire. Electric current is measured in amperes (amps) and refers to the number of charges that move through the wire per second. Expressed in calculations as I.

current at maximum power (Impp) (Français: courant à puissance maximale)
Impp is the current (amps) when the power output of a module is the greatest. Impp under Standard Test conditions can be found on the module data sheet.

current-voltage (I-V) curve (Français: courbe courant-tension (I-V))
A graphical representation of the relationship between the voltage applied across an electrical device and the current flowing through it. It is one of the most common methods of determining how an electrical device functions in a circuit.

cutoff voltage (Français: tension de coupure)
The voltage at which a battery is considered fully discharged, beyond which further discharge could cause harm.

cycle (Français: cycle)
Refers to batteries. One discharge and one recharge equates to a cycle. The cycle life of batteries is the number of charge and discharge cycles that a battery can complete before losing performance.

DC (direct current) (Français: CC (courant continu))
Direct current is an electric current flowing in one direction only and substantially constant in value. Energy emitted by batteries and PV modules is DC.

deep cycle battery (Français: batterie à cycle profond)
A deep-cycle battery is a lead-acid battery designed to be regularly deeply discharged using most of its capacity.

deep discharge (Français: décharge profonde)
Applies especially to lead-acid batteries. Deep discharge is withdrawal of 50% or more (in some cases, 80% or more) of the rated capacity of a cell or battery. Deep discharge of batteries not designed for this purpose often leads to mechanical stresses in the plates, which leads to shedding, poor conductivity, and a diminished lifetime of the system. In worst case, the battery cannot be charged anymore after a deep discharge.

depth of discharge (DOD) (Français: profondeur de décharge (DOD))
Depth of discharge is the percentage of the battery that has been removed relative to the total battery capacity. A battery with an 80% DoD will have a 20% SOC (state of charge) left.

diode (Français: diode)
A diode is a semiconductor device that essentially acts as a one-way switch for current. It allows current to flow easily in one direction, but severely restricts current from flowing in the opposite direction, just like a one-way-street for electrical current. A typical application of of diode includes rectifying a voltage, such as turning AC into DC voltage.

discharge (Français: décharge)
Discharging, or draining, is the opposite of charging, and describes the process of your battery losing voltage, or energy. A battery is always discharging anytime it is not being directly charged, even if you are not using it to power your devices.

discharge rate or C rate (Français: taux de décharge ou taux C)
C-rate is a measure of the rate at which a battery is discharged compared to it’s nominal capacity. A 1C rate (or a rate of C1) means that the discharge current will completely discharge the battery in 1 hour; a rate of C20 equates to the current that will completely discharge the battery in 20 hours.

downtime (Français: temps d’arrêt)
Any period where the PV system cannot provide power to the load, expressed either in hours per year or as a percentage. Downtime may be due to technical failure or lack of maintenance (for instance, dirty solar panels that need to be washed).

efficiency (Français: efficacité)
Solar panel efficiency is a measurement of how much of the sun’s energy a certain solar panel can convert into usable electricity. The data is gathered through testing done in lab conditions which may not emulate real-world conditions in your specific location.

electric circuit (Français: circuit électrique)
An electrical circuit is a complete route that an electric current (or electricity) can flow around.

electric current (Français: courant électrique)
Electric current is the movement of electrons through a wire. Electric current is measured in amperes (A or amps) and refers to the number of charges that move through the wire per second. Expressed in calculations as I.

electrical grid (Français: réseau électrique)
An electric grid or power grid is a network of synchronized power providers and consumers that are connected by transmission and distribution lines and operated by one or more control centers. South Africa has one national grid owned by Eskom.

electricity (Français: électricité)
A fundamental form of energy observable in positive and negative forms that occurs naturally (as in lightning) or is produced (as in a generator) and that is expressed in terms of the movement and interaction of electrons. Electricity is a secondary energy source that we get from the conversion of other sources of energy such as coal, natural gas, oil, nuclear power, even sunlight. These sources are known as “primary sources”. Primary sources can be renewable or non-renewable, but the electricity itself is neither.

electron (Français: électron)
Electrons are the smallest of the particles that make up an atom, and they carry a negative charge.

energy (Français: énergie)
Power derived from the utilisation of physical or chemical resources, especially to provide light and heat or to work machines.

equinox (Français: équinoxe)
Either of the two occasions in the year when the centre of the sun is directly above the Equator, and day and night are approximately equal in length.

frequency (Français: fréquence)
Frequency is how often something repeats. In the case of electrical current, frequency is the number of times a sine wave repeats, or completes, a positive-to-negative cycle. The more cycles that occur per second, the higher the frequency.
gel-type battery (Français: batterie de type gel)
A gel battery is a valve regulated, maintenance free, lead acid battery. Gel batteries are extremely robust and versatile. These type of batteries produce few fumes and can be used in places without much ventilation.

grid (Français: réseau)
An electric grid or power grid is a network of synchronized power providers and consumers that are connected by transmission and distribution lines and operated by one or more control centers. South Africa has one national grid owned by Eskom.

grid parity (Français: parité du réseau)
Grid parity (or socket parity) occurs when an alternative energy source can generate power at a levelized cost of electricity (LCOE) that is less than or equal to the price of power from the electricity grid.

grid-connected system (Français: système raccordé au réseau)
Operates as per grid-tied system but can incorporate battery banks for the storage and deploment of energy in the case of grid failure or for use during your power provider’s high-tariff periods.

grid-tied system (Français: système raccordé au réseau)
A grid-tied system uses solar panels to generate electricity from sunlight. Excess power is exported to the utility grid, and similarly, when the household requires more power, those needs are met by imports from the grid. In the purest use of the term, there is no battery bank present.

high voltage disconnect (Français: déconnexion haute tension)
High Voltage Disconnect is used to ensure that an electrical circuit is completely de-energised for service or maintenance. Such switches are often found in electrical distribution and industrial applications, where machinery must have its source of driving power removed for adjustment or repair.

hybrid system (Français: système hybride)
In the truest sense of the words, a hybrid system will make use of a combination of energy sources, including grid power, solar and power, battery banks as well as diesel generators. However, systems that are grid-connected with battery backup, and can draw from the sun, the battery bank or the grid, are also referred to as hybrid systems.

incident light (Français: système hybride)
Incident light is the light that falls on a subject. It can be from natural lighting, like the sun, or from an artificial source.
A fraction of incident light power can be converted to electrical power by a solar cell or module.

input voltage (Français: tension d’entrée)
The input voltage is the voltage you supply to the board into a linear voltage regulator. (the amount of energy put into a device)

insolation (Français: insolation)
Insolation is the solar radiation that reaches the earth ‘s surface. It is measured by the amount of solar energy received per square centimetre per minute.

inverter (Français: onduleur)
A piece of equipment in every solar system that safely converts DC power (direct current) from your solar panels and batteries to the AC power (alternating current) required by your household appliances.

I-V curve (Français: courbe I-V)
The I-V (current-voltage) curve of a PV string (or module) describes its energy conversion capability at the existing conditions of irradiance (light level) and temperature.

joule (Français: joule)
A joule is the basic unit of energy, equal to the kinetic energy of a kilogram mass moving at the speed of one meter per second (one joule is a kg⋅m2⋅s−2).
kilowatt (kW) (Français: kilowatt (kW))
A measure of 1000 watts of electrical power. 1000W = 1kW

kilowatt-hour (kWh) (Français: kilowattheure (kWh))
A measure of electrical energy. Equal to 1000 watts (or 1kW) of electricity used continuously for one hour.

lead-acid battery (Français: batterie au plomb)
A battery with lead electrodes and dilute sulphuric acid as the electrolyte. The first type of rechargeable battery ever created.

life-cycle cost (Français: coût du cycle de vie)
The estimated cost of owning, operating, and disposing of a solar PV system over its useful life.

liquid electrolyte (Français: électrolyte liquide)
Battery electrolyte is the liquid substance found in most car batteries. It’s sometimes referred to as battery acid because it’s highly acidic. It is made from a mixture of water and sulfuric acid.

load (Français: charge)
The combined power (in W or kW) of all the devices that you want to power.

load current (A) (Français: courant de charge (A))
Load current is the current that the appliance is drawing at that instant. A full load current, is the maximum current a device can operate.

load forecasting (Français: prévision de la charge)
Load forecasting is a technique used by power or energy-providing companies to predict the power/energy needed to meet the demand and supply equilibrium.

load resistance (Français: résistance de charge)
load resistance is the cumulative resistance of a circuit, as seen by the voltage, current, or power source driving that circuit. This includes the resistance of the wires and the resistance of any devices connected to those wires.

low voltage disconnect (Français: déconnexion basse tension)
The LVD feature on a charge controller turns off the load of a system automatically when the load drains the battery bank to a low voltage. LVD protects your batteries from reaching a depth of discharge that may damage them and reduce their lifespan.

maximum power point (MPP) (Français: point de puissance maximale (MPP))
The MPP (Maximum Power Point) is the operating point at which the test object (solar, PV module) delivers maximum power.

maximum power point tracker (MPPT) (Français: suiveur du point de puissance maximale (MPPT))
The MPPT tracks the voltage and current from the solar module to determine when the maximum power occurs in order to extract the maximum power. The MPPT then adjusts the voltage to the battery to optimize the charging. This results in a maximum power transfer from the solar module to the battery.

megawatt (MW) (Français: mégawatt (MW))
a unit of power equal to one million watts, especially as a measure of the output of a power station.

megawatt-hour (Français: mégawattheure)
A measure of electrical energy. Equal to 1000 kilowatts (or 1MW) of electricity used continuously for one hour.

module (Français: module)
A solar panel

mounting system (Français: système de montage)
Solar mounting systems are used to fix solar panels onto a variety of surfaces, such as rooftops, parking lots or land. Mounting systems help keep the solar panels or arrays in place and work as the support structure for solar modules. Mounting systems are generally made from steel or aluminium supports that can hold solar arrays in place through extreme loads from wind, snow and frost. There are different types of mounting systems, such as rooftop, ground-mount, and carport systems

multicrystalline (Français: polycristallin)
The Multi-crystalline silicon is also called as Poly-crystalline silicon and Polysilicon. Multi-crystalline silicon is solid silicon composed of many crystallites/grains of varying size and orientation. It is used extensively in manufacture of polycrystalline solar panels and electronics. Because of lower silicon purity, poly-crystalline solar panels are not quite as efficient as mono-crystalline solar panels and need to cover a larger surface to output the same electrical power as you would with a solar panel made of mono-crystalline silicon.

Nominal or Normal Operating Cell Temperature (NOCT) (Français: Température nominale ou température normale de fonctionnement des cellules (NOCT))
The Nominal Operating Cell Temperature (NOCT) (sometimes referred to as Normal operating cell temperature) is defined as the temperature reached by a solar panel under a set of conditions that are more in line with real world conditions than STC. NOCT uses the ambient air temperature to guage performance , not the cell temperature as in STC.

nominal voltage (Français: tension nominale)
Nominal voltage refers to the named or maximum voltage at which a specific circuit or system is designed to operate without damaging the equipment, such as a battery or solar array. Nominal voltage often varies from the actual voltage that a system operates at. It is simply a convenient way to refer to a voltage class without needing to be precise. Nominal voltage is sometimes referred to as nominal voltage rating or rated voltage.

ohm (Français: ohm)
The unit in which electrical resistance is measured. 1 ohm is the resistance in a wire when a current of 1 ampere flows through it with 1 voltage applied to both its ends.

open-circuit voltage (Voc) (Français: tension en circuit ouvert (Voc))
The open circuit voltage (VoC) is the maximum voltage that the solar panel can produce with no load on it (as measured with a multimeter across the open ends of the wires attached to the panel). The voltage is generally highest mid-morning as the sun rises rapidly and the panel temperature is still quite low.

operating point (Français: point de fonctionnement)
The operating point corresponds to a point on the power-voltage (P-V) curve. If this operating point is the MPP of the curve, the system will generate the most power.

orientation (Français: orientation)
Solar orientation is the positioning of a site, building, or space in relation to cardinal directions and, more importantly, the sun’s path. The orientation and inclination (mounting angle) of photovoltaic panels depends on the latitude in which we are. The optimal orientation of the panels will be south (in the northern hemisphere) or north (in the southern hemisphere) and the optimum inclination will depend on the latitude of the site, the time of the year in which it is to be used and whether or not it other sources of energy will be brought into play.

overcharge (Français: surcharge)
A solar panel can overcharge a battery if it generates more voltage than the battery can handle. The correct charge controller can prevent overcharging by reducing the current that goes into the system. Overcharging a solar batter decreases its lifecycle quickly. Even one overcharging episode can ruin a solar battery. If overcharging occurs for long enough, the battery can explode or catch fire and self-combust.

panel (Français: panneau)
A PV module, a solar panel

parallel connection (Français: connexion parallèle)
One of two methods of connecting system components (such as batteries in your battery bank, solar modules in your solar array). In series connection, you connect the negative terminal of item to the positive terminal of the next items, and so on through the string. In parallel connection, the negative terminal of one item is connected to the negative terminal of the next, and so on through the string. The same is done with the positive terminals, ie positive terminal of one item to positive terminal of the next. Parallel connections increase the capacity of combined components, and series connections increase the voltage.

peak demand/load (Français: demande/charge de pointe)
The peak load/demand is an often short time, in which the highest demand of electricity is needed from the grid. Peak load/demand fluctuations may occur on daily, monthly, seasonal and yearly cycles.

peak power current (Français: courant de puissance de pointe)
Inverters are rated in continuous power and peak/surge power. Continuous power is the total WATTS the inverter can support indefinitely while peak/surge power is the amount of power that the inverter can provide for a brief period, usually when the equipment/appliance starts up.

peak sun hours (Français: pic d’ensoleillement)
Peak sun-hours are not the same as “hours of daylight”. Peak sun-hours refers specifically to how much sun exposure is usable for efficient energy production in an area during a typical day. A peak sun-hour, specifically, is an hour during which the intensity of sunlight is 1,000 watts per square meter.

photon (Français: photon)
The basic unit of all light, a particle of light

photovoltaic (PV) array (Français: champ photovoltaïque (PV))
A photovoltaic array is a connected system of multiple solar panels or PV modules. PV arrays can contain as little as one panel or module per system, or as many as the thousands that are found in solar farms.

photovoltaic (PV) cell (Français: cellule photovoltaïque (PV))
A solar cell, also called photovoltaic cell, any device that directly converts the energy of light into electrical energy through the photovoltaic effect. Together, many cells are part of a solar module, which is the power generating part of a solar system

photovoltaic (PV) module (Français: module photovoltaïque (PV))Photovoltaic modules consist of PV cell circuits sealed in an environmentally protective laminate, and are the fundamental building blocks of PV systems. A semiconductor material, usually silicon, is the basis of each individual solar cell, many of which make up the module. PV Modules are the part of a PV System that captures the sunlight and turn it into electricity

photovoltaic (PV) panel (Français: panneau photovoltaïque (PV))
A PV panel is basically a solid-state semiconductor device that converts light energy into electrical energy. There are different types of panels like mono- or polychrystaline which each have their advantages and disadvantages. A panel consists of one or more solar modules.

photovoltaic(s) (PV) (Français: photovoltaïque(s) (PV))
Photovoltaics is the direct conversion of light into electricity at the atomic level. Some materials exhibit a property known as the photoelectric effect that causes them to absorb photons of light and release electrons. When these free electrons are captured, an electric current results that can be used as electricity.

polycrystalline (Français: polycristallin)
Polycrystalline materials, or polycrystals, are solids that are composed of many crystallites of varying size and orientation. This material is being used to build polycrystalline PV Cells.

power conversion efficiency (Français: rendement de conversion de puissance)
Power losses are an accepted reality of converting power from DC to AC and vice versa, although the amount varies. The energy preserved during the process determines the inverter efficiency rating. An inverter with an 85% efficiency rating means 15% of the converted energy cannot be used. Newer inverters have a 90% to 95% efficiency, but there is no 100% efficient inverter yet.

REIPP (Français: REIPP )
Renewable Independent Power Producer Programme (REIPPP). Aimed at bringing additional megawatts onto the country’s electricity system through private sector investment in solar, wind, biomass and small hydro, among others.

resistance (R) (Français: résistance (R) )
Resistance to electricity–that is, electrical resistance–is a force that counteracts the flow of current. In this way, it serves as an indicator of how difficult it is for current to flow. Resistance values are expressed in ohms (Ω). When an electron differential exists between two terminals, electricity will flow from high to low. Resistance counteracts that flow. The greater the resistance, the lower the current. Conversely, the lower the resistance, the greater the current.

roof hook (Français: crochet de toit)
Roof hooks are parts of the mounting system for the solar panels. They are used on tiled roofs and their function is to support the rails, on which the solar panels are mounted.

self-discharge (Français: autodécharge)
Self-discharge refers to self-running electrochemical processes which cause batteries to discharge even if no electrical consumers are connected. Self-discharge decreases the shelf life of batteries and causes them to have less than a full charge when actually put to use. High ambient temperatures are a leading contributor to battery self-discharge.

semiconductor (Français: semi-conducteur)
A semiconductor can be defined as a substance with properties of a conductor and insulator both. It is composed of a crystal material whose ability to conduct electricity rises as its temperature goes up. That is, it sometimes acts as a conductor and sometimes as an insulator. A semiconductor can help controlled flow of electricity. The basic function of such a device is to switch ON and OFF the flow of electricity as and when required.

series connection (Français: connexion en série)
One of two methods of connecting system components (such as batteries in your battery bank, solar modules in your solar array). In series connection, you connect the negative terminal of item to the positive terminal of the next items, and so on through the string. In parallel connection, the negative terminal of one item is connected to the negative terminal of the next, and so on through the string. The same is done with the positive terminals, ie positive terminal of one item to positive terminal of the next. Parallel connections increase the capacity of combined components, and series connections increase the voltage.

solar energy (Français: énergie solaire)
Solar energy is created when solar technologies convert sunlight into electrical energy either through photovoltaic (PV) panels or through mirrors that concentrate solar radiation. This energy can be used to generate electricity or be stored in batteries or thermal storage.

stand-alone system (Français: système autonome)
Also called an off-grid system. Used in areas that are not easily accessible or have no access to an electric grid. A standalone system is independent of the electricity grid, with the energy produced generally being stored in batteries. A typical standalone system would consist of a PV module or modules, inverter, batteries, and a charge controller. A diesel generator may also form part of such a system to ensure power over periods when neither the solar panels or the battery banks can supply power (extended overcast/rainy days that result in low yield from panels, required both to power appliances and recharge the batteries).

standard test conditions (STC) (Français: Conditions Standards de Test (STC))
Standard Test Conditions (STC) are the industry standard laboratory conditions under which all solar PV panels are tested to determine their rated power and other characteristics. When a panel is advertised as having a capacity of 350Wp for example, this is the power it is expected to produce under STC. Since all manufacturers follow this same standard, it gives a fair basis to compare them against each other.

standby current (Français: courant de veille)
This is the current that electronic equipment draws when it is off but has some standby power supplying the sense circuits such as the PS On power in a computer power supply.

state-of-charge (SOC) (Français: état de charge (SOC))
The SOC is a ratio of the available capacity that corresponds with the maximum possible charge that can be stored in the battery. This is expressed in a percentage (i.e. a SOC of 63%).

transformer (Français: transformateur)
A transformer is a device that transfers electric energy from one alternating-current circuit to one or more other circuits.
It can be designed to “step up” or “step down” voltages and works on the magnetic induction principle.
volt (V) (Français: volt (V))
The volt (symbolized V) is the Standard International (SI) unit of electric potential or electromotive force. A potential of one volt appears across a resistance of one ohm when a current of one ampere flows through that resistance. The volts are thus named in honor of Alessandro Volta, the inventor of the battery.

voltage (Français: tension)
Voltage is the pressure from an electrical circuit’s power source that pushes charged electrons (current) through a conducting loop, enabling them to do work such as illuminating a light. Voltage is the cause of current (being an effect). Current is the effect caused by Voltage.

voltage, Open Circuit (VoC) (Français: tension en circuit ouvert (VoC))
Open circuit voltage is how many volts the solar panel outputs with no load on it. If you just measure with a voltmeter across the plus and minus leads, you will read Voc. Since the solar panel isn’t connected to anything, there is no load on it, and it is producing no current. This is a very important number, as it is the maximum voltage that the solar panel can produce under standard test conditions, so this is the number to use when determining how many solar panels you can wire in series going into your inverter or charge controller.

voltage protection (Français: protection de la tension)
Voltage protection is the process of securing an electrical system from the possible damages that may be caused by overvoltage through the use of devices like a high voltage protector, which cuts the output electric supply whenever it gets hazardous input voltage.

watt (W) (Français: watt (W))
A watt is a unit of power. It is equivalent to one joule per second, corresponding to the rate of consumption of energy in an electric circuit where the potential difference is one volt and the current one ampere.

watt hour (Français: wattheure)
A watt-hour is a unit of energy. It is the amount of energy an item consumes over a given timeframe. For example, a 10W phone charger used for 1 hour consumes 10Wh. The same 10W charger used for 4 hours consumes 40Wh.

yield (Français: rendement)
The amount of energy of energy (in watts, kW, MW and so on) actually harvested from your solar PV system, taking into consideration external factors like heat, dirt, and shade.
zenith angle (Français: angle zénithal)
The solar zenith angle is the angle that is formed between the sun and vertical (or straight up) at any given point on the earth. For instance, if the sun was straight in front of an observer at the horizon, the angle between horizontal and vertical would be 90°. Whereas, if the sun were directly overhead the zenith would be 0° because there is no angle between it and vertical.