Glossary

What is being monitored? What does it mean? Browse our guide to solar-related terminology or find definitions of the data parameters.

Terminology

Alternating Current (AC): …is electrical current that alternates the direction of its flow in cycles. The grid supplies AC electricity at a frequency of 50 Hz in all Australian states which means that the peak value of the sine wave is reached 50 times a second.

Amorphous Silicon: …is a thin film photovoltaic material based on silicon with no crystal structure. Silicon, doped with other particles, is applied in a thin layer to the substrate of the PV module. Amorphous silicon has a lower efficiency than crystalline silicon, but it requires less silicon material and is cheaper to process so can provide a cost advantage.

Array: An assembly of electrically connected PV modules that combines their output

Cadmium Telluride (CdTe): An alternative photovoltaic material (to silicon) which is used in some thin film PV modules

Concentrator: A system used to concentrate sunlight onto the surface of a PV module to increase its electrical output

Conversion Efficiency: Ratio of the electric power produced by a PV module to the power of the sunlight reaching its surface, noted as a percentage (%)

Copper Indium Gallium Selenide (CIGS): An alternative photovoltaic material (to silicon) which is used in some thin film PV modules

Crystalline Silicon: …refers to silicon in its crystalline form, which can be grown in mono- or polycrystalline configurations to make solar PV cells. Silicon crystals are grown and sawn into wafers to construct these cells. Crystalline silicon has a more rigid atomic structure than amorphous (non-crystalline) silicon, which allows electrical current to flow more easily. Crystalline silicon PV modules make up the overwhelming bulk of modules on the PV market.

Current: The amount of electricity flowing through an electrical circuit, measured in Amperes [Amps] [A]

Diffuse irradiance: Light scattered by particles in the atmosphere, which hits the surface of an array at an angle other than 90 degrees, generally expressed in Watts per quare metre (W/m2)

Direct Current (DC): …is electricity that flows continuously in one direction; this is the type of electricity generated by PV modules. To supply DC electricity to the grid, or to use it with standard appliances, an inverter must be used to convert this DC to AC. AC electricity can also be converted into DC by using a rectifier.

Direct normal irradiance (DNI): Light that hits the surface of the array on an angle close to 90 degrees (normal), generally expressed in Watts per square metre (W/m2)

Dual-axis tracking: …refers to a tracking system that can rotate about two axes. Dual-axis tracking can align a PV array to the sun’s height in the sky (tilt angle) as well as the sun’s east-to-west bearing (azimuth angle).

Electrical grid: An electrical distribution and/or transmission system made up of interconnected supply sources (generators) and demand points (loads) that supplies electrical energy to a town or other area

Energy: …is the ability to do work. PV modules are able to convert the energy in sunlight to electrical energy, generally expressed in watt hours (Wh) or kilowatt hours (kWh)

Grid-Connect Inverter: …is a type of inverter designed to feed electricity to the grid, generally with in-built safeguards to guarantee normal operation of the grid. Its primary role is to convert the DC power generated by the PV system into AC power that can be transmitted and distributed on the grid.

Grid-Connected PV System: A PV system that contributes generated electricity to the grid via a grid-connect inverter

Hydraulics: …describes a mechanical system based on the expansion and contraction of enclosed gasses or liquids. Passive hydraulic trackers are designed to use differences in heat in different areas to shift an array.

Insolation: …is a measure of solar energy per unit area, generally expressed in Wh/m2 or kWh/m2. When cited as the solar resource for a given location, this can be expressed in peak sun hours per day, defined as an equivalent number of hours of 1 kWh/m2 sunlight encountered.

Inverter: A device for converting DC electricity into AC electricity, often also having the ability to control other functions in a grid-connected or a standalone power system

Irradiance: A measure of solar power per unit area, generally expressed in W/m2 or kW/m2

Kilowatt [kW]: A unit of electrical power equal to 1,000 W which can be calculated as the product of voltage and current

Kilowatt-hour [kWh]: A unit of electrical energy equal to 1,000 Wh, representing the power delivered over a period of time, e.g. 5 kWh = 1 kW acting over 5 hours (or 5 kW acting over 1 hour, etc.)

Module: In photovoltaics, a piece of equipment that converts sunlight to electricity – also known as a ‘solar panel’

Monocrystalline: With respect to silicon, a type of photovoltaic material cut from silicon blocks composed of a single, pure silicon crystal, known for high conversion efficiencies but generally more expensive to manufacture

Orientation: Alignment of an array with respect to north – also known as ‘azimuth’

Parallel Connection: … refers to the connection of electrical elements along two or more parallel paths (i.e. positive terminals to positive terminals and negative terminals to negative terminals) in an electrical circuit. PV modules connected in parallel will sum their currents, while voltage will stay the same.

Passive Tracking: Tracking that does not consume electrical energy, e.g. a hydraulic tracker which moves in response to temperature changes in different parts of a fluid

Peak Demand: Maximum power demand from a load source, often measured in kW – also known as ‘peak load’

Peak Sun Hours: A measure of solar energy received, defined as the equivalent number of hours experiencing 1 kWh/m2 insolation, e.g. if a location receives 7 kWh/m2 over the course of a day, this would be expressed as 7 peak sun hours

Photon: A particle of light

Photovoltaic (PV) Cell: …is a small piece of photovoltaic material that generates electricity from light. A PV module is made up of an assembly of electrically connected photovoltaic cells.

Photovoltaic (PV) Material: Material that generates an internal electrical current in response to light, by a phenomenon known as the photovoltaic effect

Photovoltaic (PV) module: A piece of equipment that uses the photovoltaic effect – converting sunlight into electricity – made up of an assembly of electrically connected photovoltaic cells – also known as ‘solar panel’

Polycrystalline (or Multicrystalline): …with respect to silicon, refers to a type of photovoltaic material cut from silicon blocks composed of multiple silicon crystals of varying size and orientation (the different crystals that make up polycrystalline cells can be seen on the surface of the cell as a mosaic-like pattern). These are slightly less efficient than monocrystalline cells but less costly to manufacture.

PV: Photovoltaic, referring to light (‘photo’) and electricity (‘voltaic’)

Series Connection: …refers to the connection of electrical elements along a single continuous path (i.e. positive terminals to negative terminals) in an electrical circuit. PV modules connected in series will sum their voltages, while current will stay the same.

Single-Axis Tracking: …refers to a tracking system that rotates about one axis. It allows a PV array to follow the sun from east to west throughout the day.

Solar panel: A piece of equipment that uses the photovoltaic effect converting sunlight into electricity, made up of an assembly of electrically connected photovoltaic cells – also known as ‘PV module’

Solar Resource: The availability of solar energy at any particular location, generally quantified in terms of insolation

Stand alone: Not connected to a grid, an example being an electrical generator that serves a load without being part of the main supply grid

String: A number of PV modules electrically connected in series

Thin Film: A type of solar technology constructed from a thin layer of photovoltaic material on the surface of a substrate such as glass (also refers to the layer itself)

Tilt Angle: The angle at which a PV module is mounted with respect to the horizontal plane

Tracking Array: An array that moves automatically to orient its PV modules towards the sun and maximise solar exposure

Upgraded metallurgical-grade silicon: A photovoltaic material made of silicon that is three orders of magnitude less pure than the polysilicon used to make polycrystalline solar cells

Voltage (V): A measure of the electrical force driving a current, quantified by the unit Volts [V]

Watt (W): The standard unit of electrical power, a product of voltage [V] and current [A]

Data Parameters

For solar generation data from the DKASC, Alice Springs and Yulara Solar System

kWh a del-rec, kWh b del-rec, kWh c del-rec, kWh tot del-rec

Energy [kWh] delivered less energy received, for each phase and the system in total (cumulative record from system installation) with 1-second readings reported every 5 minutes, measured with a Class 0.2 meter with ±0.2% accuracy (ION7550, CT: 5/100

5-Min-Avg kWa, 5-Min-Avg kWb, 5-Min-Avg kWc, 5-Min-Avg kWtot

AC power [kW] for each phase and the system in total, based on 1-second readings averaged over 5 minutes, measured with a Class 0.2 meter with ±0.2% accuracy (ION7550, CT: 5/100)

5-Min-Avg V1THD, 5-Min-Avg V2THD, 5-Min-Avg V3THD

Total harmonic voltage distortion for phases a, b and c (as 1, 2 and 3): the ratio of the powers of voltage harmonic components to the power of the base frequency, measured with ±1.0% accuracy (ION7550, CT: 5/100)

5-Min-Avg Vln a, 5-Min-Avg Vln b, 5-Min-Avg Vln c.

Line-to-neutral AC voltage for each phase, measured ±0.1% accuracy (ION7550, CT: 5/100)

5-Min-Avg Ia, 5-Min-Avg Ib, 5-Min-Avg Ic

AC current [A] on each phase, measured with ±0.1% accuracy (ION7550, CT: 5/100)

5-Min-Avg Vllav

Average of the three line-to-line voltages, based on 1-second values averaged over 5 minutes, measured with a Class 0.2 meter with ±0.1% accuracy (ION7550, CT: 5/100)

5-Min-Avg PFa, 5-Min-Avg PFb, 5-Min-Avg PFc

Power factor for phases a, b and c expressed as a percentage, based on 1-second values averaged over 5 minutes, measured with ±0.2% accuracy (ION7550, CT: 5/100)

5-Min-Avg Freq

AC frequency measured in Hz, based on 1-second values averaged over 5 minutes, measured with an accuracy of ±0.005 Hz (ION7550, CT: 5/100)

5-Min-Avg I1THD, 5-Min-Avg I2THD, 5-Min-Avg I3THD

Total harmonic current distortion for the phases a, b and c (as 1, 2 and 3): the ratio of the powers of all current harmonic components to the power of the base current frequency, with 1-second samples averaged over 5 minutes, measured with ±1.0% accuracy (ION7550, CT: 5/100)

kWh Del-Rec

Energy [kWh] delivered less energy received, for the system in total (cumulative record from system installation) with 1-second readings reported every 5 minutes, measured with a Class 0.5 meter with ±0.5% accuracy (ION6200, CT: dependent on technology – see below)

5-Min-Avg I

AC current [A] based on 1-second samples averaged over 5 minutes; for readings below 5% of the full scale, accuracy is 0.3% and for greater than 5% of the full scale, accuracy is 0.3% + 0.05% of the full scale (ION6200, CT: 50/5 except Solar Inception large-scale trackers, 100/5)

5-Min-Avg kW

AC power [kW] based on 1-second values averaged over 5 minutes, measured with a Class 0.5 meter with ±0.5% accuracy (ION6200, CT: 50/5 except Solar Inception large-scale trackers, 100/5)

5-Min-Avg ITHD

Total harmonic current distortion: the ratio of the powers of all current harmonic components to the power of the base current frequency, with 1-second samples averaged over 5 minutes, measured with ±1.0% accuracy (ION6200, CT: 50/5 except Solar Inception large-scale trackers, 100/5)

Performance ratio (PR)

A quantity commonly used in the PV industry to assess the performance of PV systems, representing the ratio of the actual energy produced by a PV system to the energy which would be produced by a ‘perfect’ system continuously operating at STC under the same irradiance (incident global irradiance in the plane)

Note: With the DKASC’s addition of a plane-of-array (POA) pyranometer in 2015, this value is automatically calculated for all fixed arrays at the DKASC and is available in the downloadable datasets (PR values commence in May 2015). The PR value for tracking arrays using a fixed pyranometer is not valid so is not calculated. It is also important to note that the POA pyranometer used for these calculations is located near Site 23 and in intermittent cloud conditions, the short-term irradiance at the POA pyranometer may differ significantly from conditions experienced by the more distal arrays and therefore, the results under these conditions will not be valid.

For resource data from the NT Solar Resource meteorological stations

Please download the metadata files for further specific details of each station’s data parameters and measurement conditions. The monitoring conforms to a Class A (IEC 61724-1) standard.

DNI Irradiance_AV

Direct normal irradiance [W/m2]: intensity of solar power striking at 90 degrees to the horizontal plane at the surface of the earth, sampled at 1-second intervals and averaged over 5 seconds, measured with <±1% accuracy (daily uncertainty) (Kipp & Zonen SHP1-V pyrheliometer)

GHI Irradiance_AV

Global horizontal irradiance [W/m2]: intensity of solar power received by a horizontal plane at the surface of the earth, sampled at 1-second intervals and averaged over 5 seconds, measured with ±2% accuracy (daily uncertainty) (Kipp & Zonen SMP10-V pyranometer)

Humidity_AV

Relative humidity [%] sampled at 1-second intervals and averaged over 5 seconds, measured with ±3% accuracy at 0-90% RH and ±4% accuracy at 90-100% RH (Vaisala HUMICAP HMP155 with radiant shield DTR503A)

POA Irradiance_AV

Plane-of-array irradiance [W/m2]: intensity of solar power received by the plane of a tilted* PV array at the surface of the earth (*at the location’s approximate latitude), sampled at 1-second intervals and averaged over 5 seconds, measured with ±2% accuracy (daily uncertainty) (Kipp & Zonen SMP10-V pyranometer)

Rainfall

Cumulative rainfall [mm] sampled at 1-second intervals and averaged over 5 seconds (high resolution specified to match other data parameters for analysis simplicity), measured with ±3% accuracy up to 380 mm/hr (RIMCO RIM7499- 020-STD tipping bucket rain gauge)

System

System availability, indicated by the connectivity status of the onsite data logger

Temperature_AV

Ambient temperature [°C] sampled at 1-second intervals and averaged over 5 seconds, measured with ±0.1°C accuracy at 15-25°C and ±0.15°C accuracy at 25-40°C (Vaisala HUMICAP HMP155 with radiant shield DTR503A)

Wind Direction_AV

Wind direction [°] sampled at 1-second intervals and averaged over 5 seconds, measured with 2° accuracy at 12 m/s (GILL WindMaster 3D ultrasonic anemometer)

Wind Speed_AV

Resultant wind speed [m/s] sampled at 1-second intervals and averaged over 5 seconds, measured with <1.5% RMS accuracy at 12 m/s (GILL WindMaster 3D ultrasonic anemometer)

Wind Vertical_AV

Vertical component of wind speed [m/s] sampled at 1-second intervals and averaged over 5 seconds, measured with <1.5% RMS accuracy at 12 m/s (GILL WindMaster 3D ultrasonic anemometer)

For historical resource data from the DKASC, Alice Springs

DKA.WeatherStation - Diffuse Horizontal Radiation

Diffuse horizontal radiation [W/m2]: light that has been scattered by atmospheric particles not in the line of direct radiation from the sun (direct being measured relative to the horizontal plane), sampled at 10-second intervals and averaged over 5 minutes, measured onsite with ±8% / ±10 W/m2 accuracy for 95% of individual readings (Delta T SPN 1 pyranometer)

DKA.WeatherStation - Global Horizontal Radiation

Global horizontal radiation [W/m2]: intensity of solar power received by a horizontal plane at the surface of the earth, sampled at 10-second intervals and averaged over 5 minutes, measured onsite with ±8% / ±10 W/m2 accuracy for 95% of individual readings (Delta T SPN 1 pyranometer)

Note: Global horizontal radiation is plotted as ‘solar insolation’ on the interactive graphing page.

DKA.WeatherStation - Radiation Diffuse Tilted

Diffuse tiled radiation [W/m2]: light that has been scattered by atmospheric particles not in the line of direct radiation from the sun (direct being measured relative to the array’s tilted plane), sampled at 10-second intervals and averaged over 5 minutes, measured onsite with ±8% / ±10 W/m2 accuracy for 95% of individual readings (Delta T SPN 1 pyranometer)

DKA.WeatherStation - Radiation Global Tilted

Global tilted radiation [W/m2]: intensity of solar power received by a the array’s tilted plane at the surface of the earth, sampled at 10-second intervals and averaged over 5 minutes, measured onsite with ±8% / ±10 W/m2 accuracy for 95% of individual readings (Delta T SPN 1 pyranometer)

DKA.WeatherStation - Weather Daily Rainfall

Daily rainfall [mm] sampled at 10-second intervals and averaged over 5 minutes, measured onsite with ±2% accuracy for intensities 24-300 mm/hr and ±3% accuracy for intensities 300-500 mm/hr and reset at midnight (TB3A tipping bucket rain gauge)

DKA.WeatherStation - Weather Relative Humidity

Relative humidity [%] sampled at 10-second intervals and averaged over 5 minutes, measured onsite at 2 m with 2% accuracy at 0-90% RH and 3% accuracy at 90-100% RH (Vaisala HMP45A with radiant shield)

DKA.WeatherStation - Weather Temperature Celsius

Ambient temperature [°C] sampled at 10-second intervals and averaged over 5 minutes, measured onsite at 2 m with ±0.2ºC accuracy (Vaisala HMP45A with radiant shield)

DKA.WeatherStation - Wind Direction

Wind direction [°] sampled at 10-second intervals and averaged over 5 minutes, measured onsite at 8 m with 3% accuracy, whichever is greater (Windcap Ultrasonic Windsensor WS425 anemometer)

DKA.WeatherStation - Wind Speed (m/s)

Wind speed [m/s] sampled at 10-second intervals and averaged over 5 minutes, measured onsite at 8 m with ±0.135 m/s or 3% accuracy, whichever is greater (Windcap Ultrasonic Windsensor WS425 anemometer)

DKASC, Alice Springs

DKP Microgrid / BESS

Yulara Solar System

NT Solar Resource

Terminology

Data Parameters

For solar generation data from the DKASC, Alice Springs and Yulara Solar System

For resource data from the NT Solar Resource meteorological stations

For historical resource data from the DKASC, Alice Springs

For resource data from the Yulara Solar System