Measurements of solar radiation

[carstenhoyerklick]

Description of the issue

After defining the basic concepts of the solar raidation components and various tracking surfaces in the issues #1076, #1448 and #1088, we can now proceed to define the actual measued values as e.g. direct normal irradiation or global horizontal radiation.

Ideas of solution

The terms should be subclassed of

I. continuant->generically dependent continuant -> information content entity -> quantity value -> areal power density -> areal solar power density

• Term: Global Horizontal Irradiance
  Definition: Global horizontal irradiance is the power (OEO00000333) of solar radiation (OEO00020038) measured on a horizontal solar radiation receiving surface (OEO00020199).

• Term: Global Tilted Irradiance
  Definition: Global tilted irradiance is the power (OEO00000333) of solar radiation (OEO00020038) measured on a tilted solar radiation receiving surface (OEO00020199) with a fixed surface azimuth angle (OEO00290002) and slope angle (OEO00290001).

• Term: Direct Normal Irradiance
  Definition: Direct normal irradiance is the power (OEO00000333) of direct solar radiation (OEO00010392) measured on a two-axis tracking surface (OEO00010397) always pointing towards the sun.

• Term: Direct Horizontal Irradiance
  Definition: Direct horizontal irradiance is the power (OEO00000333) of direct solar radiation (OEO00010392) measued on a horizontal solar radiation receiving surface (OEO00020199).

• Term: Diffuse Horizontal Irradiance
  Definition: Diffuse horizontal irradiance is the power (OEO00000333) of diffuse solar radiation (OEO00010393) measued on a horizontal solar radiation receiving surface (OEO00020199).

II. continuant->generically dependent continuant -> information content entity -> quantity value -> areal energy density -> areal solar energy density

• Term: Global Horizontal Irradiation
  Definition: Global horizontal irradiation is the energy (OEO00000150) of solar radiation (OEO00020038) measured on a horizontal solar radiation receiving surface (OEO00020199) over a temporal region (BFO00000008).

• Term: Global Tilted Irradiation
  Definition: Global tilted irradiation is the energy (OEO00000150) of solar radiation (OEO00020038) measured on a tilted solar radiation receiving surface (OEO00020199) with a fixed surface azimuth angle (OEO00290002) and slope angle (OEO00290001) over a temporal region (BFO0000008).

• Term: Direct Normal Irradiation
  Definition: Direct normal irradiation is the energy (OEO00000150) of direct solar radiation (OEO00010392) measured on a two-axis tracking surface (OEO00010397) always pointing towards the sun over a temporal region (BFO0000008).

• Term: Direct Horizontal Irradiation
  Definition: 'Direct horizontal irradiation is the energy (OEO00000150) of direct solar radiation (OEO00010392) measued on a horizontal solar radiation receiving surface (OEO00020199) over a temporal region (BFO0000008).'

• Term: Diffuse Horizontal Irradiation
  Definition: 'Diffuse horizontal irradiation is the energy (OEO00000150) of diffuse solar radiation (OEO00010393) measued on a horizontal solar radiation receiving surface (OEO00020199) over a temporal region (BFO0000008).'

III. Axioms

We have a number of axioms in the discussion of #1076

• "An areal solar energy density (irridiation) is an areal energy density that gives the arriving energy of solar radiation per area. A synonym for areal solar energy density is irradiation."
• "A horizontal areal solar energy density (horizontal irridiation) is an areal energy density that gives the arriving energy of solar radiation on a horizontal area."
• same for power density, normal, inclined, vertical...

Do we need them, or are they part of the definitions above?

###. IV Further terms
There is more terms, which do not have a clear naming yet:

• Global radiation on a two-axis-trackign surface: 'Global Normal Irradiance/Irradiation'
• Global radiation on a vertical plance: 'Global Vertical Irradiance/Irradiation'
• do we need Diffuse and Direct Tilted?

Workflow checklist

• I discussed the issue with someone else than me before working on a solution
• [x ] I already read the latest version of the workflow for this repository
• [x ] The goal of this ontology is clear to me

I am aware that

• every entry in the ontology should have a definition
• classes should arise from concepts rather than from words

[mschroedter]

Ok from my side to the definitions. Thank you.

Can we somewhere add that 'beam' is used as synonym for 'direct' in our community?
Background: This allows to use acronyms as BHI, DHI and GHI without mixing up the direct and diffuse in the 'D' and to avoid a double use of DHI fo direct and diffuse horizontal irradiance.

[l-emele]

Acronyms could be added as alternative labels as well as the term starting with beam.

[stap-m]

All proposed classes are quantity values and this should be reflected in the defs.
Further, we should discuss to refer to energy amount value, power value and time span instead (the resp quantity values).
I.e. for example:
Global horizontal irradiation is an areal solar energy density that measures the amount of energy of solar radiation on a horizontal solar radiation receiving surface over a time span.
Etc.

[l-emele]

I spoke last week shortly with @carstenhoyerklick about the axiomatisation of these classes. I thought about this a while, but I think we cannot yet fully axiomatise everything that is in the proposed definition of: Global horizontal irradiation is an areal solar energy density that measures the amount of energy of solar radiation on a horizontal solar radiation receiving surface over a time span.

We can add the following axioms:
'global horizontal irradiation' SubClassOf: 'areal solar energy density'
'global horizontal irradiation' SubClassOf: 'quantity value of' some 'time span'

To axiomatise the relation to horizontal solar radiation receiving surface we probably need a new object property.

However, there are things that we should axiomatise at different places. For example the fact that solar radiation transfers energy should be axiomatised as:
'solar radiation' 'has energy participant' some 'solar energy'

[stap-m]

'global horizontal irradiation' SubClassOf: 'quantity value of' some 'time span'

Better would be 'global horizontal irradiation' SubClassOf: 'is about' some 'one-dimensional temporal region'. time span is a quantity value itself.