Glossary

This wiki contains a glossary of all terms used in the Solar Forecast Arbiter. It will eventually be the single source of truth for definitions. Inventing a YAML format for now. See Variable names for programming conventions.

AC capacity:
  - Units: MW
  - Definition: maximum AC power generation potential under ideal conditions

AC power:
  - Units: MW
  - Definition: measurement or forecast of AC generation at an instant or averaged over a period of time

Availability:
  - Units: %
  - Definition: The percent of the power plant that is able to generate power.

CDF

Curtailment:
  - Units: MW
  - Definition: The generation limit that is imposed during curtailment periods.

DC capacity:
  - Units: MW
  - Definition: maximum DC power generation potential under ideal conditions

DC power:
  - Units: MW
  - Definition: measurement or forecast of DC generation at an instant or averaged over a period of time

Diffuse horizontal irradiance:
  - Units: W/m^2
Direct normal irradiance:
  - Units: W/m^2
Global horizontal irradiance:
  - Units: W/m^2
PDF
Plane of Array Irradiance:
  - Units: W/m^2
Relative Humidity:
  - Units: %
Surface temperature:
  - Units: C
Surface wind speed:
  - Units: m/s


Surface tilt:
  - Units: degrees
  - Definition: tilt from horizontal of a fixed tilt system, degrees (flat = 0 degrees, vertical = 90 degrees)
Surface azimuth:
  - Units: degrees
  - Definition: azimuth angle of a fixed tilt system, degrees (North = 0 degrees, East = 90 degrees)


Axis tilt:
  - Units: degrees
  - Definition: tilt from horizontal of the tracker axis (flat = 0 degrees, vertical = 90 degrees)
Axis azimuth:
  - Units: degrees
  - Definition: azimuth angle of the tracker axis (North = 0 degrees, East = 90 degrees)
Ground coverage ratio:
  - Definition: ratio of total width of modules on a tracker to the distance between tracker axes. For example, for trackers each with two modules of 1m width each, and a spacing between tracker axes of 7m, the ground coverage ratio is 0.286(=2/7). system
Backtrack:
  - Definition: True/False indicator of if a tracking system uses backtracking
Maximum rotation angle:
  - Units: degrees
  - Definition: maximum rotation from horizontal of a single axis tracker



Temperature Coefficient:
  - Units: 1/C
  - Definition: The fractional amount by which DC power generation changes in response to a change in temperature. Typically -0.002 to -0.005 per degree C.

Tracking type:
  - Definition: type of tracking system, i.e. fixed, single axis, two axis

Irradiance loss factor:
  - Units: %
  - Definition: applied to POA irradiance after reflection losses but before spectral mismatch losses.
  - Default: 0
DC loss factor: 
  - Units: %
  - Definition: applied to DC current. 
  - Default: 0
AC loss factor: 
  - Units: %
  - Definition: applied to inverter power output.
  - Default: 0


Name:
  - Definition: name for the Site, e.g. Desert Rock
Latitude:
  - Units: degrees
  - Definition: latitude of the Site in decimal degrees north of the equator, e.g. 36.62373
Longitude:
  - Units: degrees
  - Definition: longitude of the Site in decimal degrees east of the prime meridian, e.g. -116.01947
Elevation:
  - Units: m
  - Definition: Elevation of the Site in meters above sea level, e.g. 1007
Timezone:
  - Definition: IANA timezone of the Site, e.g. Etc/GMT+8


Network:
  - Definition: measurement network name, e.g. SURFRAD
Well-Known Text:
  - Definition: describes a geometric area for a Site which may be physically extended, e.g. a polygon over a city for a Site that describes many distributed generation PV systems.