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Elements - Normal Solar versus Direct Normal Radiation

asked 2015-10-16 08:07:26 -0500

Gio's avatar

updated 2020-01-20 13:34:59 -0500

I'm trying to use Element software to create new weather files.

Now i have some doubts about the outputs: it gives me back the "Normal Solar" instead of the "Direct normal Radiation" that E+ should demand.

Am I wrong?

I couldn't find a way to force this variable because it's related to the "Global solar" and to the "Diffuse solar" through an equation. Therefore I can't set all three variables: one is auto-calculated.

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@Michael OKeefe will have the answer for this.

ericringold's avatar ericringold  ( 2015-10-16 10:19:54 -0500 )edit

(I changed the title of the question to make it clearer and removed greetings per convention)

Julien Marrec's avatar Julien Marrec  ( 2015-10-16 11:05:14 -0500 )edit

2 Answers

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answered 2015-10-16 13:00:33 -0500

Yes, you are correct that Elements enforces an equational relationship between the various weather variable attributes. This can cause some challenges when adding new information -- I suggest an approach below.

First, let me mention the equation relationship as follows:

Z = the hourly averaged zenith angle in radians

Global Solar = total irradiation on a horizontal surface

Diffuse Solar = diffuse irradiation on a horizontal surface

Normal Solar = beam normal irradiation, yes, this is "Direct normal Radiation"

These are related as follows:

GlobalSolar = NormalSolar * Cos(Z) + DiffuseSolar

Note that the cosine of the zenith angle (Z) depends on your latitude and longitude so before doing any solar editing, make sure you have set the proper location and time zone in the header.

Elements currently enforces this relationship even when cutting and pasting. You can pull up the "Cosine of Zenith" as another column ("Columns: ADD" at bottom left) and also the Solar Hour Angle for reference (0 is solar noon; +/- 180 is midnight).

If you want to paste in new global solar values from Excel, probably the best way to do it is to select the DiffuseSolar column and scale by "0" to reset the values to 0 (holding Normal Solar constant). Then Scale NormalSolar with a scale factor of "0" holding DiffuseSolar constant. This should "zero out" your solar variables. Then, when you paste into GlobalSolar (holding NormalSolar constant), the values you paste in should "take". If you have your own information for the beam normal and diffuse split, you can alternately paste those in and Elements will add up the GlobalSolar based on the above relationship.

In summary, when using Elements to add solar data:

  1. set your correct timezone, latitude, and longitude in the header
  2. select the diffuse column holding normal constant and scale by 0
  3. select the normal solar column holding diffuse constant and scale by 0
  4. paste the normal solar data in holding diffuse constant
  5. paste the global solar data in holding normal constant (note: there will be a slight lag on this step as Elements has to inverse solve for each point)

Hope this helps.

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I was about to add to my question that I would need to set all 3 data (the equation provides a different result, one out of 3 everytime of course) ... but I notice you anticipated my question.

I couldn't expect a better answer, it helps a lot. Thank you

Gio's avatar Gio  ( 2015-10-17 08:02:04 -0500 )edit

I tried to use your guideline but I couldn't solve the problem with the third value of radiation

Gio's avatar Gio  ( 2015-10-19 10:21:01 -0500 )edit

This is probably related to a known issue in Elements 1.0.4. We will be releasing 1.0.5 very soon and that should fix this issue -- sorry, for any problems this may be causing you.

Michael OKeefe's avatar Michael OKeefe  ( 2015-10-19 11:47:08 -0500 )edit

I just wanted to be sure I was not making a mistake... You don't need to say sorry. It works fine, could be great to have the auto-calculation as option (a very nice option); this is my opinion. Thanks for all!

Gio's avatar Gio  ( 2015-10-20 03:43:47 -0500 )edit

I am trying to make a new weather file using Elements. I am trying to copy and paste my solar data into the Normal Solar column, however it is not pasting. I was directed to this question and I tried the suggestion of scaling the diffuse solar and normal solar columns to zero, but when I try scaling the either column it does not work (i.e. nothing happens). Any ideas on how I can get my solar data into Elements? Thank you

RChidwick's avatar RChidwick  ( 2016-01-21 15:03:17 -0500 )edit

answered 2016-04-19 04:35:06 -0500

luis melo's avatar

How can I edit the date values in ELEMENTS to a timestep from 1 hour to 10 minutes?

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@luis melo please do not hijack others' questions with new ones, this location is for answers to the original question only. Instead, please delete and start a new question for this after searching to see if it has been asked before. See the help page.

MatthewSteen's avatar MatthewSteen  ( 2016-04-19 06:56:23 -0500 )edit

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Asked: 2015-10-16 08:07:26 -0500

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Last updated: Apr 19 '16