Hi Sathya,

Thanks for posting here in the forum!

To model sunshine in a non-sequential system, I would recommend to use the Source Radial. You can add a max. angle of  0.25 degrees and make the source color a Black Body Spectrum at 6000K in the visible wavelengths.

The first section of this Knowledge Base article describes it in more details:

• How to simulate a rainbow

Feel free to reach out again if you need more help or if you have follow up questions.

Best,

Dear Flurin, Thanks for prompt response. I followed the steps to design sunshine in non-sequential model. But it leads to another problem. 

The following figure shows the parameters which I set for sunshine.

This spectrum should be my input to the system.

But the system takes the wavelength in the system explorer tab.

I have listed out the following questions 

1. How can we give the black body spectrum as input to my system? Even if I choose visible range results in same condition.
2. What is mean by minimum angle in source radial tab?
3. If the maximum angle is 0.25 then all the ray coming out from source subtended at 0.25deg?
4. Before this “source radial” I used source two angle as source in my work. Does source two angle replicate the angle subtended by the sun if i enter ± 0.27deg in the option?

 Kindly suggest.

Hi Sathya,

Hope you are doing well.

First up:

As the objective of the example I referred to is to simulate a rainbow, therefore the system contains a water material sphere (Raindrop) and a standard mirror to simulate the sky (Gaussian scattering).

If you don't need these feature you can get rid of them.

If you have another system and you want to apply sunlight “just” as stray light, I would recommend this KBA:

• Introduction to stray light analysis

Your Questions:

1 - To input the the the black body spectrum into your source, you can open the source properties of your source radial , as the sun has an effective temperature of approximately 5800 K you can add 6000 k..

The Spectrum: describes the discrete wavelengths within the defined wavelength range.

2,3- The min and max Angle in degrees (Parameter 8 and 9 in Source Radial) define the angular boundaries of your source. As the distribution angle of the source is the same as the apparent angular of the sun, you can add 0.25 degress into the maximum angle (Parameter 9)

4- If you wanna use another source such as source two angle you can do that, then you can even control the divergence.

Feel free to reach out if that doesn't help you. Then we could maybe look into your specific system.

Best

Hello Flurin, Thanks for your advice.

I am designing 10.1cm fresnel lens in zemax. For that I have lens specifications from Edmund optics. But i dont know how to calculate the 2nd, 4th and 6th order coefficient for this lens.

The below shown image is an lens model for reference.

Can you help me to get sort out this issue?

Out of curiosity, what distance and half-widths were used for the sun here?

I’m trying to model the sun to be used with multiple heliostats (positionable reflecting mirrors) reflecting onto a single receiver. I need direct radiation (e.g. parallel rays) from the sun to all of the heliostats and am having trouble getting the system to mimic reality. As mentioned above, the sun takes up an angle of 0.25 degrees in the sky, is very large and very, very far away, causing all the rays to be more or less parallel, from the point of view of every heliostat. Maybe I’m overcomplicating it? 

The sun illuminates earth with a semi-angle of 0.25 degrees (full angle of 0.5 degrees).  In a non-sequential solar collector model based on a Source Two-Angle (circular angular shape, uniform in angle space), it shouldn’t really matter what the specific distance is to the source.  It’s the angular content that is of primary concern.  As long as the spatial half-widths of the source are chosen so that the optical system is fully illuminated (but not significantly overfilled with rays that are wasted), then you should be good.  Of course you can then tip/tilt the optical system relative to the source in order to mimic illumination from a particular orientation of the sun in the sky.

Thanks Jeff,

your explanation helps. Do you think it’s a fair assumption that all the rays from the sun would be parallel? 

I need to dig into the solar power reference books to confirm..

Thanks,

Josh

It depends on what your optical system is.  If it’s a conventional PV solar panel then assuming sunlight is a collimated beam is likely okay.  However, if it’s a concentrator, then it’s probably best to include the actual 0.5-degree angular spread.  In other words, the source should be a collection of collimated ray bundles distributed uniformly over a circular region of 0.5-degree diameter in angle space (which is precisely what the Source Two-Angle can provide). 

A quick search shows many sites that provide the value of the sun’s angular diameter.  Here’s one: How to Calculate the Angular Diameter of the Sun

We know that sunlight is not strictly collimated because if it were, then the sun would appear to our eye to look like a point source in the sky (i.e., like a distant star).  Instead, it’s round with a finite diameter, corresponding to illumination of the earth’s surface with a 0.5-degree angular diameter.

Jeff.Wilde wrote:

It depends on what your optical system is.  If it’s a conventional PV solar panel then assuming sunlight is a collimated beam is likely okay.  However, if it’s a concentrator, then it’s probably best to include the actual 0.5-degree angular spread.  In other words, the source should be a collection of collimated ray bundles distributed uniformly over a circular region of 0.5-degree diameter in angle space (which is precisely what the Source Two-Angle can provide). 

A quick search shows many sites that provide the value of the sun’s angular diameter.  Here’s one: How to Calculate the Angular Diameter of the Sun

We know that sunlight is not strictly collimated because if it were, then the sun would appear to our eye to look like a point source in the sky (i.e., like a distant star).  Instead, it’s round with a finite diameter, corresponding to illumination of the earth’s surface with a 0.5-degree angular diameter.

Thank you sir, that was a useful insight as I am working on developing solar concentrator for a high-energy local start-up.

Hello Everyone,

Is opting for a solar radial source a suitable decision, or should I consider selecting a Source two angle for simulating the sun?