Glossary#
This glossary contains terms and definitions used in SunPeek and ISO 24194 Power Check. The Basis column indicates where each term originates:
ISO 9488 (Solar energy — Vocabulary)
ISO 9806 (Solar energy — Solar thermal collectors — Test methods)
ISO 24194 (Solar energy — Collector fields — Check of performance)
SunPeek (terms specific to SunPeek)
Term |
Definition |
Basis |
|---|---|---|
AOI |
Angle of Incidence, i.e. the angle between the beam radiation on a surface (typically the collector plane) and the normal to that surface. |
Guide |
Average estimated power output |
Average of estimated power output for all valid intervals of Power Check. |
Guide |
Average measured power output |
Average of measured power output for all valid intervals of Power Check. |
Guide |
Average power ratio |
Average of estimated power output divided by average of measured power output (for all valid intervals of Power Check). |
Guide |
Collector array |
Defined in ISO 9488:2022 as a group of solar collectors that are closely connected in series, in parallel, or in a combination of both modes, with one hydraulic input and one hydraulic output. |
ISO 9488 |
Collector field |
This term is not explicitly defined in ISO 24194 but is presumably used synonymously with collector array. For the ISO 24194 Power Check, a collector field is the technical object for which Power Check is performed. This requires a common power measurement either on the primary or secondary side. SunPeek uses the term (collector) array instead of collector field. |
ISO 24194 |
Collector model |
A collector with distinct name and dimensions, and one set of collector performance parameters listed in the data sheet (if tested according to a standard or quality assurance scheme like Solar Keymark). |
Guide |
Collector type |
As collector types, ISO 9488:2022 lists, among others, flat-plate, evacuated tubular, concentrating, and WISC (wind and infrared sensitive collector) collectors. ISO 24194 mentions single- and double-glazed flat-plate collector types. |
ISO 9488 / ISO 24194 |
Cosine effect |
Reduction of the receiving area for beam / direction radiation caused by the cosine angle θ formed between the beam solar radiation and the normal of the collector plane: Gb = DNI · cos(θ) |
Guide |
Data channel |
Collection of measured or calculated values associated with a specific quantity / measurand. For Power Check, all data channels are given as time series data where each measured value has an associated timestamp. In CSV files, the name of a data channel is usually the column head (e.g., Hemispherical Irradiance, Collector Field Inlet Temperature, Angle of Incidence). |
Guide |
Data record |
Hourly-mean values of a specific 1-hour interval, containing all data channels relevant for the measured-estimated comparison. To make Power Check traceable, the Guide recommends including measured, calculated, and explanatory variables when reporting the (valid) data records. |
ISO 24194 |
Evaluation period |
Period from which the valid intervals of Power Check are selected, equal to or a subinterval of the measurement period. |
Guide |
Heterogeneous collector field |
A heterogeneous collector field is more complex than a uniform collector field, e.g., due to using multiple collector types, having multiple subgroups of collectors connected in parallel or serial, irregular row spacing, irregular mounting angles, etc. Such cases are not covered in the ISO 24194 Power Check. |
SunPeek |
Hourly-mean data |
Arithmetic averages of (valid) raw data over 1-hour intervals. The ISO 24194 Power Check requires intervals to start and end at full hours (e.g., 11:00, 12:00, 13:00, etc.) and assigns the last timestamp of the averaging interval to the hourly-mean data. |
ISO 24194 |
IAM |
Incidence Angle Modifier. |
ISO 9806 |
Measured-estimated power ratio |
Estimated power output divided by measured power output of a Power Check interval. |
Guide |
Measured value (MV) |
Quantity value representing a measurement (GUM). |
GUM |
Measurement data |
(Raw) data obtained by a measurement device. |
Guide |
Measurement data channel |
Data channel originating from a measurement, containing measured values. |
Guide |
Measurement period |
Period for which data of an installation is logged. |
Guide |
Plant |
System using solar energy for the delivery of thermal energy (ISO 9488:2022). System and installation are used as synonyms for plant. A plant can have one or multiple collector fields, which can be uniform or heterogeneous. |
ISO 9488 |
POA |
Plane of Array, as in POA irradiance: Solar irradiance measured or modeled in the plane of the collector field. |
Guide |
PVC |
Performance Verification Criterion, comparing average estimated power output to average measured power output for all valid data records. |
Guide |
QDT |
Quasi-dynamic test (QDT) procedure according to ISO 9806. |
ISO 9806 |
Raw data |
Data at original sampling rate as recorded from measurement device (e.g., hemispherical irradiance measured by a pyranometer) or calculated (e.g., angle of incidence, temperature difference, mean collector temperature and ambient air). Some data loggers include basic data quality checks. |
Guide |
Sampling rate |
Length of time interval for which the data is acquired and stored (logging time). |
ISO 24194 |
Sensor |
Element of a measuring system that is directly affected by a phenomenon, body, or substance carrying a quantity to be measured (GUM). A sensor is typically associated with a data channel but may require additional sensor properties to make use of the measured value. |
GUM |
Sensor mapping |
Linking measurement data channels with input slots for computations as part of the SunPeek plant configuration. See Sensor Mapping for detailed documentation. |
SunPeek |
Sensor properties |
Specifications of a Sensor, e.g., tilt and azimuth of an irradiance sensor, to interpret / process its measured values. |
SunPeek |
Sensor type |
Sensor category associated with a measurement data channel in SunPeek, determines allowed physical units and data replacement scheme. |
SunPeek |
SST |
Steady-state test (SST) procedure according to ISO 9806. |
ISO 9806 |
Uniform collector field |
Collector field consisting of one collector model with a geometrically uniform arrangement, i.e. same mounting (tracked or fixed with constant tilt and azimuth) and row spacing with a rectangular shape on a plane. If no external shading occurs, collectors within rows can be assumed to receive similar irradiance levels. For the ISO 24194 Power Check, uniform collector fields have one set of efficiency parameters to be used in Formulas 1–3. |
SunPeek |
Valid interval / Valid data record |
Data record fulfilling the data filtering criteria of Power Check. |
ISO 24194 |
Valid data point |
In ISO 24194, this term is presumably used synonymously with “valid data record”. The authors of the Guide suggest deprecating this term. |
ISO 24194 |
Valid raw data |
Raw data after applying data quality checks. SunPeek excludes physically impossible values and replaces measurement values slightly outside physically possible limits that might occur due to measurement uncertainties. |
Guide |
Virtual Sensor |
Similar to a Sensor but not related to a measuring system. Its values are calculated based on other (virtual) sensors and optionally on parameters. Used in SunPeek to replace missing sensors or calculate required inputs for subsequent analysis like solar position, or internal (row-to-row) shading of collector rows. |
SunPeek |
WISC |
Wind and infrared sensitive collector. WISC refers to a collector type that is particularly sensitive to wind and/or infrared radiation like uncovered co-generating / PVT and solar air heating collectors (as opposed to flat-plate, evacuated tubular, concentrating collectors). |
ISO 9488 / ISO 9806 |