rewrite functions in pv_model #689
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| @@ -333,7 +334,7 @@ final case class PvModel private ( | |||
| val e0 = 1.000110 + | |||
| 0.034221 * cos(jInRad) + | |||
| 0.001280 * sin(jInRad) + | |||
| 0.000719 * cos(2d * jInRad) + | |||
| 0.00719 * cos(2d * jInRad) + | |||
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According to Iqbal, this is 0.000719 with three zeroes. The primary source, Spencer, also states the same. Duffie and Zheng as well. Please check again.
Furthermore, could you add the missing sources I just mentioned to the list of sources in documentation as well?
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This is Duffie p. 9, where I noticed the 2 zeros only. Can you maybe send me the PDFs of the other books, so I can look it up aswell?
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Interestingly, the fifth edition of Duffie seems to differ from all earlier editions in this point. Given that the cited sources stayed the same and I didn't find any other explanation (and the layout seems broken in this edition for the first time), I assume that the change did not happen on purpose and the number with three zeros is still correct. There should be some more investigations here, though.
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It'd be great if we added commentary to the readthedocs documentation regarding this issue, i.e. why we're using the fourth edition and not the fifth. (Extraterrestrial Radiation)
| @@ -551,12 +581,12 @@ final case class PvModel private ( | |||
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| if (eDifH.value.doubleValue > 0) { | |||
| // if we have diffuse radiation on horizontal surface we have to check if we have another epsilon due to clouds get the epsilon | |||
| var epsilon = ((eDifH + eBeamH) / eDifH + | |||
| var epsilon = ((eDifH + eBeamH / cos(thetaZInRad)) / eDifH + | |||
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Both Duffie and the original Perez use the formula as before. Where did you find the formula with cos thetaZ again?
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This is my reference (Duffie p. 95f). Note that "I_b,n" is not the beam radiation on a horizontal surface, but rather the beam radiation on a surface normal to the direction of the sun. This can be calculated by dividing the beam radiation on a horizontal surface "I_b" (=eBeamH in code) by cos(ThetaZ). This is also demonstrated in Duffie: example 2.16.2
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I think we need some more investigation here, probably focused on the weather data specification. I_b,n is certainly the "normal beam incidence radiation", which means the radiation in direction of the beam, i.e. on a surface that is exactly facing the sun, as you explained. I_b is certainly the radiationon a horizontal plane (i.e. on earth's surface).
All of this is illustrated by figure 1.8.1 in Duffie (4th ed).
The current source we use, Myers, is not quite clear on this. In Perez 1990 it is clearly stated, though: The "normal incidence direct irradiance" is asked for (formula (1), p. 273).
The question now becomes which type of radiation the weather data sources provide. For ERA5, solar radiation always seems to be specified on a horizontal plane. I have not found the specs for ICON and COSMO yet.
So it seems likely to me that you're right with your assumptions. What should be done now is adapting the formula in documentation (replace E_beamH with E_beamH/cos(theta_Z)). Also it be nice to add a hint for fig. 1.8.1 in Duffie to the source.
# Conflicts: # src/main/scala/edu/ie3/simona/model/participant/PvModel.scala
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I also have two more points regarding documentation (readthedocs):
The link to source for Iqbal.1983 has become invalid. Could you find a new link here (could just be a link to the respective page of the publisher, if nothing else is available)? Also please check all other links.
Also related to literature: Could you also indicate page numbers for each source? This has already been done for some sources, but is missing for others. It can speed up understanding the model a bit.
Signed-off-by: Sebastian Peter <[email protected]>
Signed-off-by: Sebastian Peter <[email protected]>
Signed-off-by: Sebastian Peter <[email protected]>
Signed-off-by: Sebastian Peter <[email protected]>
| @@ -473,9 +473,9 @@ class PvModelTest extends Specification { | |||
| // 0.244 MJ/m^2 = 67.777778 Wh/m^2 | |||
| //Beam Radiation on horizontal surface | |||
| Irradiation eBeamH = Sq.create(67.777778d, WattHoursPerSquareMeter$.MODULE$) | |||
| // 0.769 MJ/m^2 = 213,61111 Wh/m^2 | |||
| // 0.796 MJ/m^2 = 221,111288 Wh/m^2 | |||
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This is a typo we made at some point, so this correction should find its way into the new PvModelSpec as well.
| @@ -15,7 +15,7 @@ @Article{Maleki.2017 | |||
| @MISC{Itaca_Sun, | |||
| author = {Itacanet}, | |||
| title = {The Sun As A Source Of Energy}, | |||
| howpublished={\url{https://www.itacanet.org/the-sun-as-a-source-of-energy/part-3-calculating-solar-angles/}} | |||
| howpublished={\url{https://de.scribd.com/document/455342846/Part-3-Calculating-Solar-Angles-ITACA}} | |||
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Not quite happy with that. We should find a new source, preferably not a web source that can just disappear at any point in time.
resolves #688
I will try to optimize the beam radiation for times close to sunrise or sunset. I will adjust the case distinction of omega1 and omega2, also allowing for smaller intervalls between them. This will be balanced out by multiplying the power with the time difference between omega2 and omega1, thus not creating very high peaks in power outputs in the morning (or evening).
Also, I removed the condition Theta_G < 90°, since that should only result in a negative value of r, which is already accounted for, making it unneccessary.
Please let me know what you think!