Solar Energy Glossary

Home Solar Energy Glossary
by Solus Energy

Confused by all the terminology, phrases and abbreviations to do with solar energy? Here is a handy guide to all those and more so understand what is being said and how it affects you.

AJAX progress indicator
Batteries Electrical Energy Grid Connection Solar Energy Solar Energy Systems Solar Panels

  • a

  • The material that readily absorbs photons to generate charge carriers (free electrons or holes).
  • Alternating current is electricity in wave form that uniformly reverses current direction according to frequency. The type of electricity that powers homes, offices, factories - life!
  • A dopant material, such as boron, which has fewer outer shell electrons than required in an otherwise balanced crystal structure, providing a hole that can accept a free electron.
  • The period of time a charged battery can be stored before its capacity falls to an unusable level. Measured at a specific temperature.
  • The activation voltage (or voltages) is the level where a charge controller will take action to protect the batteries.
  • User adjustable setting to adjust the voltage levels the charge controller will become active.
  • A measure of a battery's capacity to supply current over time. Depending on the use Ah can be used to show the amount of current supplied over an hour, the battery capacity to supply power and can vary depending on how the battery is used due the batteries internal characteristics.
  • Direct current fuses. Should be rated with a sufficient rating to interrupt the highest possible current.
  • An indication of the solar radiation path length through the atmosphere. Calculated as cosine of the zenith angle (the angle from directly overhead to a line intersecting the sun). The directly overhead has a path length of 1 (one atmosphere thickness).
  • Alternating current is electricity in wave form that uniformly reverses current direction according to frequency. The type of electricity that powers homes, offices, factories - life!
  • A non‐crystalline semiconductor material that has an irregular atomic structure (long range order). Amorphous silicon is used for thin film solar cells, although other materials eg cadmium telluride (CdTe) are being used instead for thin film cells due to low manufacturing efficiencies using(...)
  • Amorphous silicon has no crystalline structure, being used in thin‐film photovoltaic cells. The silicon thin film cells are manufactured in the slow process of depositing layers of doped silicon on a substrate leading to low manufacturing efficiency.
  • An Amp (A) is the unit of measurement for the rate of flow of electrons / electric charge flowing per second within a conductor.
  • Direct current fuses. Should be rated with a sufficient rating to interrupt the highest possible current.
  • A measure of a battery's capacity to supply current over time. Depending on the use Ah can be used to show the amount of current supplied over an hour, the battery capacity to supply power and can vary depending on how the battery is used due the batteries internal characteristics.
  • The angle that a ray of sunlight makes with a line perpendicular to the surface of the solar panel. When the solar panel surface directly faces the sun the solar angle of incidence is zero. If the solar panel surface is parallel to the sun the angle of incidence is 90°. The angle of incidence(...)
  • The annual energy savings attributable to a solar power system relative to the energy requirements of a non‐solar system building. Usually calculated as the electricity used before the system is installed less electricity used after the system is active. Used to calculate the payback period of(...)
  • The terminal of a battery that pushes electrons into an external circuit. The anode and cathode reverse when charging a battery.
  • Thin coating of material on a solar cell surface that increases light transmission and reduces the light reflection.
  • The electrical current produced by a solar array when it is exposed to sunlight.
  • The electrical voltage produced by a solar array when it is exposed to sunlight and connected to a circuit.
  • Usually measured in hours per year, availability shows how long a solar energy system is able generate power. Often expressed as a percentage compared to theoretical generation hours over the same period as one of the measures of how well the panels are performing. Downtime is the opposite.
  • The direction that your roof faces (in the context of solar). The azimuth is measured in degrees, representing the angle between your roof and true south.

  • b

  • All components and costs other than the photovoltaic modules/array. Includes design costs, land, site preparation, system installation, support structures, power conditioning, operation and maintenance costs, indirect storage and related costs.
  • For semiconductors the band gap is the energy difference between the highest valence band and the lowest conduction band. The basis of generating electricity in solar cells is when a photon of light gives up it's energy to an electron to enable the electron to cross the band gap into the(...)
  • Energy (in electron volts) required to free an outer shell electron from its orbit about the nucleus to a free state promoting it from the valence to the conduction level. In solar power this energy is provided by a photon of light. See Band Gap.
  • A measure of the electrostatic potential of the interface (cell barrier) between the n-type and p-type layers in a solar cell. This is the energy lost by an electron in penetrating the cell barrier.
  • The lowest amount of energy the grid or solar system must supply in a given period. Base load can be applied to any entity requiring power - a house, office, factory, town, region or the country.
  • Two or more electrochemical cells enclosed in a container and electrically interconnected in an appropriate series/parallel arrangement to provide the required operating voltage and current levels. Also used commonly to describe a single cell if the cell makes up the entire electrochemical(...)
  • The maximum available charge, expressed in ampere‐hours, that can be used from a cell or battery under a specific set of operating conditions including discharge rate, temperature, initial state of charge, age, and cut‐off voltage. This is different to battery capacity which is the maximum(...)
  • Maximum total electrical charge in ampere‐hours, which a battery can deliver to a load under a specific set of conditions. This differs from battery energy capacity which is the total energy capacity in kWh.
  • Simplest operating unit in a storage battery. Made up of one or more positive electrodes / plates, an electrolyte that permits ionic conduction, separators between plates of opposite polarity, one or more negative electrodes / plates and a container for all the above.
  • Battery electric vehicles that only have a battery to store energy to power the vehicle - a true electric vehicle.
  • Battery energy capacity is the total energy available for use from a fully charged cell battery in kWh. This differs from battery capacity which is the total electrical charge capacity in Ah but like battery capacity varies with battery conditions  - temperature, use rate, age, etc.
  • Battery energy storage is simply storing energy in electrochemical batteries to be used in a number of ways, the most obvious is time shifting energy generation to use either at home, commercially or on the grid. Another direct advantage to battery storage for electricity users is peak shaving(...)
  • The period of time in which a cell or battery is capable of operating above a specified capacity or efficiency performance level. Life may be measured in cycles and/or years, depending on the type of service for which the cell or battery is intended.
  • Battery electric vehicles that only have a battery to store energy to power the vehicle - a true electric vehicle.
  • Have solar cells on both sides of the panel to make the most of reflected light. Only used in raised systems. Extra cost vs benefit has to be carefully calculated.
  • Solar panels that can be integrated with a building’s construction, typically replacing other conventional building materials while simultaneously serving as power generators. These modules can be integrated into building facades, roofing by replacing traditional roofs, awnings, and some solar(...)
  • An electrical one‐way valve that allows electrons to flow forwards, but not backwards. The blocking diode is connected in series with solar cell(s) and a storage battery to keep the battery from discharging through the cell(s) when there is no or low output from the solar cell.
  • Boron is an element commonly used as the dopant in photovoltaic device or cell material to enable the electrical generation process to work.
  • All components and costs other than the photovoltaic modules/array. Includes design costs, land, site preparation, system installation, support structures, power conditioning, operation and maintenance costs, indirect storage and related costs.
  • A sausage‐shaped synthetic single‐crystal mass grown in a special furnace, pulled and turned at a rate necessary to maintain the single‐crystal structure during growth. Individual wafers are then cut from the boule which then are treated and combined to form a solar cell.
  • One British Thermal Unit is equal to 252 calories or the amount of heat required to raise the temperature of one pound of water one degree Fahrenheit. Used in thermal systems to measure energy use.
  • One British Thermal Unit is equal to 252 calories or the amount of heat required to raise the temperature of one pound of water one degree Fahrenheit. Used in thermal systems to measure energy use.
  • Solar panels that can be integrated with a building’s construction, typically replacing other conventional building materials while simultaneously serving as power generators. These modules can be integrated into building facades, roofing by replacing traditional roofs, awnings, and some solar(...)
  • A bypass diode is an electrical one‐way valve connected across one or more solar cells in a photovoltaic module such that the diode will conduct if the cell(s) become reverse biased. It protects these solar cells from thermal destruction in case of total or partial shading of individual solar(...)
  • Energy (in electron volts) required to free an outer shell electron from its orbit about the nucleus to a free state promoting it from the valence to the conduction level. In solar power this energy is provided by a photon of light. See Band Gap.

  • c

  • The number of charge / discharge cycles, to a specified depth of discharge a cell or battery can undergo before failing to meet its specified capacity or efficiency performance criteria.
  • Cadmium Telluride is used an alternative to silicon in thin film solar cells due to lower cost and better environmental credentials. The downside is relative rarity of the telurium, it's toxicity compared to other PV materials and a lack of experience in recycling the CdTe solar cells.
  • Ratio of the average load on, or power output of, an electricity generating unit or system to the capacity rating of the unit or system over a specified period of time.
  • A battery having electrolyte immobilized in gel or absorbed in material eg not liquid electrolyte.
  • The terminal of a battery where electrons enter the battery completing the circuit from the anode through the external circuit to the cathode. The anode and cathode reverse when charging a battery.
  • Cadmium Telluride is used an alternative to silicon in thin film solar cells due to lower cost and better environmental credentials. The downside is relative rarity of the telurium, it's toxicity compared to other PV materials and a lack of experience in recycling the CdTe solar cells.
  • The cell barrier is a very thin interface between the n-type and p-type layers in a solar cell that inhibiting the movement of electrons from one layer to another causing higher energy electrons to move in one direction. This electron movement creates a current and voltage across the cell(...)
  • A cell junction is the centre of the cell barrier as the area of direct contact between the n-type and p-type layers in a solar cell.
  • A type of inverter. For large solar systems eg solar farms / parks with alternative wiring architecture.
  • A charge carrier is an electron or hole in a semiconductor that is free to move through the material carrying an electric charge. In a solar cell when an electron absorbs the energy from a photon moving the electron into the conduction band thus enabling free movement through the cell's(...)
  • Regulates the electricity going into a battery, and protects the battery charge during off hours. A charge controller is needed because a battery can be damaged by a fluctuating charge, which would happen if the battery were connected directly to the solar panel system.
  • The charge factor indicates how many hours must pass after a specified amount of electricity has been discharged for the battery to regain its initial condition of charge. See also discharge factor and self discharge.
  • The charge rate is the level of current that can be applied to a battery to store energy. This varies depending on the battery, it's level of charge and operating conditions.
  • The increase in solar intensity caused by reflected irradiance from nearby clouds.
  • A combined collector is a solar panel that collects both electricity and thermal energy at the same time.
  • A solar energy system whose electricity is shared by more than one household and/or office building.
  • Lenses or Fresnel lens to direct and concentrate sunlight increasing the power flux of sunlight up to hundreds of times onto a solar cell of smaller area. Most concentrator arrays must directly face or track the sun to be effective. Not on standard solar panels for this reason.
  • An energy level in a semiconductor that allows electrons to move freely and current to flow. In solar panels electrons gain the energy to move into the conduction band by absorbing the energy carried by photons of light from the sun.
  • A conductor is simply the material that electricity is transmitted through. This can be a thin strip of metal in a solar cell, wires and the cables in transmission lines.
  • Contact resistance is the resistance to electricity flow between metallic conductor contacts and the semiconductor in the solar cell.
  • A converter uses electronic circuits to convert one DC voltage to a different DC voltage. In a solar energy system this could be to convert an array voltage into the charging voltage for the solar battery. The AC equivalent to change voltages is a transformer.  
  • To protect a battery from damage, the cut-off voltage is the voltage level(s) at which the charge controller disconnects the photovoltaic array from the battery (charging) or the load from the battery (discharging).

  • d

  • The number of consecutive days an offline / stand‐alone solar energy system will meet a defined load without solar energy input i.e. from batteries. Days of storage is also related to system availability.
  • Direct current is electricity that flows in one direction and is the type of electricity that comes from solar panels, batteries, thermocouples. Requires an inverter to convert to AC for use in homes, offices etc.
  • A deep cycle battery is designed to be discharged to a low state of charge (<20%) over many charging / discharging cycles. Most batteries prefer to operate between 20% and 80% state of charge.
  • A deep discharge is discharging a battery to less than 20% of the battery's full charge capacity. Unless a deep cycle battery is used for applications where this happens regularly, the battery's health and lifespan can be affected.
  • Dendrites are growth of material in a slim needle or tree like structure and can be positive or negative. Positively they are used as part of the process to form polycrystalline silicon crystals for solar cells. In batteries used outside their design capabilities, dendrites form shortening the(...)
  • The depth of discharge is a percentage showing how much charge has been used from a battery compared to a full charge. So if a battery has a total capacity of 100kWh and 40kWh are used then the depth of discharge is 40%. DOD is the opposite of state of charge, in this example the state of(...)
  • Modular electrical power generating technologies combined with energy management and storage systems to improve electricity supply and distribution. They can be connected to the electricity grid or used off grid.
  • Especially important as a critical design criteria in offline systems, the design month is the month or 30 day period with the highest ratio between demand (high) and PV generation (low).  Simply what solar energy system design can supply the required energy for this month?
  • Solar radiation received at a solar panel after scattering and reflection in atmosphere and on the ground.
  • The mean distance a free electron or hole moves in a semiconductor before recombining with another hole or electron.
  • Diodes act as a one way valve for electricity so current only flows in one direction round a circuit. Like solar cells, a diode uses n and p type semiconductors but in a different arrangement to allow the current to flow as designed. In solar energy systems  they are found in multiple parts(...)
  • Direct beam radiation is solar radiation that reaches the surface of the Earth in a direct line from the Sun. Atmospheric conditions reduce the level of direct radiation, on clear dry days by 10%, on heavy cloud days by 100%. Depending on how you want to use the radiation depends on how it is(...)
  • Direct current is electricity that flows in one direction and is the type of electricity that comes from solar panels, batteries, thermocouples. Requires an inverter to convert to AC for use in homes, offices etc.
  • The discharge factor is defined as a fraction of the overall battery capacity that, when expressed as a number, represents the amount of time in hours that a battery can be discharged at a constant current. For example, C/5 represents a discharge factor of 5 hours. See also charge factor and(...)
  • The rate at which current is drawn from the battery over a time period.
  • Disconnects the system from the electricity supply. Check regulations for siting, ICE etc.
  • Modular electrical power generating technologies combined with energy management and storage systems to improve electricity supply and distribution. They can be connected to the electricity grid or used off grid.
  • Localised / on-site power generation such as solar energy systems.
  • The depth of discharge is a percentage showing how much charge has been used from a battery compared to a full charge. So if a battery has a total capacity of 100kWh and 40kWh are used then the depth of discharge is 40%. DOD is the opposite of state of charge, in this example the state of(...)

  • e

  • A battery's end of life capacity is the capacity left when the battery reaches it's rated end of life indicated by charge/discharge cycles, usually between 80 and 85% of the original capacity e.g. a 10kW 6,000 cycle battery will have  80% of 10kW = 8kW after 6,000 cycles. At one cycle a day(...)
  • An energy audit is an assessment that evaluates how much energy is consumed in a home and identifies ways to make a home more energy efficient. An energy audit can help homeowners recognize patterns or problems that may, over time, waste energy and money. Energy audits come with(...)

  • f

  • Feed-in tariffs are long-term agreements that allow utilities to purchase energy from customers who use FIT-eligible sources to generate renewable energy.
  • Feed-in tariffs are long-term agreements that allow utilities to purchase energy from customers who use FIT-eligible sources to generate renewable energy.

  • g

  • A solar energy system that is connected to the grid. An grid connected system can export excess solar energy production  to the grid potentially earning income or credit for electricity bill, and import electricity from the grid when the solar energy system does not produce enough energy to(...)
  • The point at which power generated by solar panels costs the same or less than power from conventional resources like natural gas.

  • h

  • Form of solar cell which as the name suggests are half the size of standard cells leading to better efficiency. Smaller size = less current = less resistance = better efficiency. Also have better shade tolerance due to size and being wired in a different manner to standard cells.

  • i

  • Current where Pmax is achieved.
  • Insolation is the amount of solar radiation energy incident on a plane surface, here a solar panel. There are two kinds of insolation - Direct insolation is the direct solar radiation incident on the solar panel from the sun. Diffuse insolation is the indirect solar radiation incident on(...)
  • Component of a solar energy system that converts the electricity generated by solar panels (DC) into a format that can be used to power your home (AC) or export to the grid.
  • Current in no-load condition. It represents the maximum current when the short circuit occurs by connecting the positive and negative leads of the wire. Important for safety to ensure the correct protective devices like fuses or breakers are used.
  • The relationship between irradiance and output of the solar panel or module - see diagram. Also illustrates that beyond a certain level the output drops to zero due to the increase in cell temperature, so factor into solar panel design.

  • k

  • The measure of electrical power used for electrical supply and export. 1kWh = 1,000 Watts.
  • The standard unit for measuring electrical power consumed or generated. 1 kWh = 1 kiloWatt of power transferred for one hour.
  • Maximum power generated by a solar panel or solar system in ideal (peak) conditions. Used to compare different designs
  • The measure of electrical power used for electrical supply and export. 1kWh = 1,000 Watts.
  • The standard unit for measuring electrical power consumed or generated. 1 kWh = 1 kiloWatt of power transferred for one hour.
  • Maximum power generated by a solar panel or solar system in ideal (peak) conditions. Used to compare different designs

  • l

  • The per-unit cost of energy from a solar energy system used to compare different generation systems both traditional and renewable / zero emission generation. LCOE is calculated by dividing the out-of-pocket cost for the system by the estimated total amount of energy the system will produce(...)
  • The per-unit cost of energy from a solar energy system used to compare different generation systems both traditional and renewable / zero emission generation. LCOE is calculated by dividing the out-of-pocket cost for the system by the estimated total amount of energy the system will produce(...)

  • m

  • A measure of electrical power used for electrical supply and export. 1MW = 1,000 kWh .
  • A standard unit for measuring electrical power consumed or generated. 1 MWh = 1 MegaWatt (1,000 kWh) of power transferred for one hour.
  • A type of inverter. Connected to each solar panel to supply AC electricity direct. Allows solar panels to be installed in parallel so fewer single points of failure. They are not Power Optimisers.
  • Type of PV Cell. The highest quality of silicon PV cell where every cell is made up from one slice of silicon crystal giving better conversion efficiency and more tolerant temperature coefficient. Uniform black look which some people prefer. Lifespan 25+ years.
  • The structure that holds the solar panels
  • An MPAN is a 13 digit reference used to identify every electricity connection point in the country. If you are exporting electricity to the grid you will require an export MPAN in additional to your normal incoming MPAN to identify the exported energy.
  • A measure of electrical power used for electrical supply and export. 1MW = 1,000 kWh .
  • A standard unit for measuring electrical power consumed or generated. 1 MWh = 1 MegaWatt (1,000 kWh) of power transferred for one hour.

  • n

  • Credits you for the excess electricity generated by your solar panels, which you can then draw upon when your panels don’t produce enough electricity to match your use. With net metering, you effectively use the electric grid to 'store' excess electricity for later use on the grid. Uses an(...)
  • The operating temperature of the solar panel cell. NOCT will be approximately 20-25°C higher than the ambient temperature, with an average temperature of around 45°C. Conditions - Air temperature: 20°C, Irradiance: 800 W/m², Wind speed: 1 m/s, Air mass: 1.5.
  • The operating temperature of the solar panel cell. NOCT will be approximately 20-25°C higher than the ambient temperature, with an average temperature of around 45°C. Conditions - Air temperature: 20°C, Irradiance: 800 W/m², Wind speed: 1 m/s, Air mass: 1.5.

  • o

  • A solar energy system that is not connected to the grid. An offline system cannot export excess production nor import electricity from the grid when the solar energy system does not produce enough energy to cover use. The system requires enough battery capacity to cover all use when the solar(...)

  • p

  • A PERC (Passivated Emitter and Rear Contact) is a manufacturing technology used in solar cells to improve their efficiency by reducing electron surface recombination, improving rear surface reflection and improves photon absorption while decreasing the heat absorption. This method of(...)
  • How long it takes to break even on a solar energy investment. The average payback period for solar energy systems varies between systems due to size, usage and whether they include battery storage.
  • One peak sun hour is one hour of sunshine at an irradiance of 1 kilowatt per square meter (kW/m2). Influenced by the time of day, the season, the presence of clouds, and geographic location eg eight hours of sunlight may be only 2 to 3 hours of peak sun.
  • A PERC (Passivated Emitter and Rear Contact) is a manufacturing technology used in solar cells to improve their efficiency by reducing electron surface recombination, improving rear surface reflection and improves photon absorption while decreasing the heat absorption. This method of(...)
  • Type of PV Cell. Third generation in development of solar cells (thin film) made from the mineral Perovskite with efficiencies demonstrated in the laboratory up to 35%. Current lifespan is limited although cheaper. Limited availability.
  • Often abbreviated to PV. A type of device that generates electricity directly from sunlight. Solar panels are photovoltaic devices. Comes from “photo” (light) and “voltaic” (voltage).
  • Photovoltaic cells are the basic component of a solar panel which comprises of many (30+) solar cells. They are made from monocrystalline or polycrystalline silicon, thin film or perovskite. Lifespan from a few to 25+ years.
  • A method of comparing photovoltaic technologies in more realistic utility setting than found under Standard Test Conditions.
  • Updated standard for cell comparison using the criteria set out by PVUSA - Air temperature: 20°C, Irradiance: 1000 W/m², Wind speed: 1 m/s, Air mass: 1.5, Tested at 10 m above ground level. PTC (Photovoltaics for Utility-Scale Applications Test Condition) will always be lower than STC but more(...)
  • The maximum rated power output at STC. Achieved just before voltage drops due to temperature increase.
  • Type of PV Cell. Cheaper silicon cells made from smaller silicon crystal fused together before slicing into wafers for use in panels. Efficiency in mid teens and lower temperature coefficient than monocrystalline panels. Have bluish look. Lifespan up to 25 years.
  • A power purchase agreement is a contract between two parties, one which generates electricity (the generator) and one which is looking to purchase electricity (the buyer).  The PPA defines all of the commercial terms for the sale of electricity between the two parties, including when the(...)
  • The maximum power of a solar panel in ideal conditions. While power rating is a good indicator of quality, most solar panels don’t experience ideal conditions for more than a few moments.
  • A power purchase agreement is a contract between two parties, one which generates electricity (the generator) and one which is looking to purchase electricity (the buyer).  The PPA defines all of the commercial terms for the sale of electricity between the two parties, including when the(...)
  • Updated standard for cell comparison using the criteria set out by PVUSA - Air temperature: 20°C, Irradiance: 1000 W/m², Wind speed: 1 m/s, Air mass: 1.5, Tested at 10 m above ground level. PTC (Photovoltaics for Utility-Scale Applications Test Condition) will always be lower than STC but more(...)
  • Often abbreviated to PV. A type of device that generates electricity directly from sunlight. Solar panels are photovoltaic devices. Comes from “photo” (light) and “voltaic” (voltage).
  • How well a PV cell converts sunlight into electricity. High-efficiency monocrystalline cells are rated in mid 20 percent,  polycrystalline cells have mid to high teens percent efficiency. PV Cell Efficiency (%) = PV Cell Electrical Output Power (W) / Incident Solar Power (W)
  • A method of comparing photovoltaic technologies in more realistic utility setting than found under Standard Test Conditions.

  • r

  • Real-time pricing is an electricity tariff where the price varies with time. In the UK this is in half hour segments. An example is the Octopus Agile tariff.

  • s

  • The Smart Export Guarantee (SEG) is a guarantee that SEG Licensees (energy companies) will pay qualifying SEG Generators (homeowners, small businesses etc) for the electricity they export via an export meter. See the Smart Export Guarantee article.
  • SEG Generators are anyone who generate under 5MW of low carbon electricity which includes all home homeowners. The electricity has to come from Solar PV, Wind, Micro Combined Heat and Power (Micro CHP), Hydro or Anaerobic Digestion (AD). Installations must be located in Great Britain and meet(...)
  • SEG Licensees are energy companies that have to pay SEG Generators for electricity they export to the grid. The export SEG tariff rates must always be above zero with the amount earned calculated from an export meter. A SEG Generator does not have to go with their current electricity supplier(...)
  • The SEG tariff is the Smart Export Guarantee price that SEG Licensees (energy companies) have to pay to qualifying SEG Generators (homeowners, small businesses etc) for the electricity they export via an export meter. See the Smart Export Guarantee article.
  • Self discharge is the rate at which a battery loses its stored energy when the electrodes are not connected to an external circuit caused by internal reactions within a battery cell. The rate of self discharge varies by battery design and their chemistry from fractions of 1% per month to(...)
  • The Smart Export Guarantee (SEG) is a guarantee that SEG Licensees (energy companies) will pay qualifying SEG Generators (homeowners, small businesses etc) for the electricity they export via an export meter. See the Smart Export Guarantee article.
  • Smart grids allow for better control of electrical generation and consumption through automation, remote control, and two-way communication between a utility and its customers. A smart grid can respond digitally to immediate changes in demand for electricity offering increased energy(...)
  • Pressure from a static snow weight that a panel can withstand before damage occurs.
  • The angle that a ray of sun makes with a line perpendicular to the surface. A panel that directly faces the sun has a solar angle of incidence of zero, if the sun is parallel to a panel the angle of incidence is 90°.
  • A collection of solar panels wired together to create the desired energy output. Residential systems aim to cover 100% of daily use whereas commercial systems may cover more or less of daily usage depending on the business.
  • Combines a heat pump with solar thermal to reduce energy used in a heat pump.
  • A solar battery is a battery included in a solar energy system to store solar energy.
  • Solar panel mounting structures that have space for activity underneath eg parking cars, farming.
  • A solar energy system lease (or solar panel leasing) is a contract with a solar energy company to have a solar power system installed on your roof or land. With a solar panel lease, you agree for the company to install a solar energy system in exchange for the electricity at preferential(...)
  • A solar lease is a contract with a solar energy company to have a solar energy system installed on your roof or land. This operates like a standard lease, the lessor (landlord) allows the solar energy company to lease the space and in this case use it for solar power. The lessor gains a known(...)
  • A clause of most solar panel leases and PPAs that increases payment rates by a fixed amount per year.
  • A loan to finance the cost of buying a solar PV system. May be from a speciality provider.
  • How well a solar panel converts sunlight into electricity. Most solar panels have 14 to 16 percent efficiency; high-efficiency panels are rated above 20 percent. This will be lower than cell conversion efficiency as other parts of the solar panel will decrease the absolute cell efficiency(...)
  • A BIPV system that replaces normal roof tiles with solar panel roof tiles instead of solar panels mounted on top of the roof.
  • Use solar energy to heat water directly to store the heat in a thermal store until required.
  • Industry standard for testing solar panels and their electrical properties for fair comparison - Cell temperature: 25°C, Solar Irradiance: 1000 W/m², Air mass: 1.5.
  • The state of charge is a percentage showing how much charge the battery has remaining compared to a full charge. So if a battery has a total capacity of 100kWh and 40kWh are used then the SOC is 60%. SOC is the opposite of depth of discharge, in this example the depth of discharge would be 40%.
  • Industry standard for testing solar panels and their electrical properties for fair comparison - Cell temperature: 25°C, Solar Irradiance: 1000 W/m², Air mass: 1.5.
  • A type of inverter. Used to convert DC to AC for a string of solar panels wired in series at higher currents and voltages. More single points of failure compared to Micro Inverters. Better suited to larger building installations.

  • t

  • How well a solar panel can perform in high-heat conditions, high heat can negatively affect solar panel performance as with all electronics and electrical systems. Expressed as (% per °C) or the percentage of peak power losses per 1°C above STC.
  • A store of heat energy. In solar thermal systems this is usually a very well insulated hot water tank, but can be thermal bricks or other store of heat energy.
  • Type of PV Cell. Second generation solar cells made up by depositing thin films of photovoltaic material onto substrate. Much thinner than crystalline silicon PV cells so lighter and more flexible. Including amorphous thin-film silicon, cadmium telluride, gallium arsenide and copper indium(...)
  • In a solar lease or PPA, the owner of the solar energy system.
  • At 1 charge / discharge cycle per day the total warranted kWh is the amount of energy a battery will store over it's lifetime.  The battery warranty period will probably expire long before the total warranted kWh is reached. For example a battery may have a 5 year warranty but a 6,000 cycle(...)
  • In a solar lease or PPA, the owner of the solar energy system.
  • A mounting system that moves the panels to optimally face the sun. Extra cost vs benefit has to be carefully calculated.
  • Windows that have solar panels incorporated into them. Not at mass commercial production yet.
  • Ideal direction for solar panels to face for maximum generation. Not magnetic south.

  • v

  • Voltage where Pmax is achieved.
  • Voltage in no-load condition and is the maximum voltage commonly used to define the solar panel configuration for the number of panels wired in series to the inverter/charge controller. Important to prevent overvoltage, which could damage the equipment.

  • w

  • A Watt is used to measure the amount of power or energy transfer. The Watt is named after Scottish inventor James Watt who greatly improved the efficiency of steam engines, one of the main components enabling the Industrial Revolution. Electrically power can be calculated as Watts = Voltage(...)
  • A Watt is used to measure the amount of power or energy transfer. The Watt is named after Scottish inventor James Watt who greatly improved the efficiency of steam engines, one of the main components enabling the Industrial Revolution. Electrically power can be calculated as Watts = Voltage(...)
  • Amount of wind force that a panel can withstand before damage and is proportional to the wind speed. Check for extreme weather events, so the panel mounting is suitable to guarantee system robustness.

You cannot copy content of this page