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# Solar Calculator - Calculate Sunrise, Sunset, and Maximum Solar Radiation

By , 10 Jan 2011
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## Introduction

I was looking for a .NET library to calculate the time the sun rises and sets. There were some libraries available, including here on The Code Project, but they had some problems. After trying some, I decided to create one myself. I needed the sunrise, sunset, and maximum solar radiation for a WordPress plug-in on my blog. The plug-in shows a map of the Netherlands together with the current weather conditions. The top of this post shows a screenshot of the plug-in. The map shows the real-time temperature including an icon. The icon is a translation of the measured solar radiation against the maximum solar radiation.

## Background

It is possible to calculate the sunrise, sunset, and maximum solar radiation using some known algorithms. For those of you who are interested in these algorithms, take a look at the following pages at Wikipedia: Declination of the Sun, Sunrise, Sunset. If you just want to calculate the sunrise, sunset, and maximum solar radiation, take a look below at how to use the code.

## Using the Code

The code is packed in a Visual Studio 2008 solution. It contains two assemblies: Astronomy and AstronomyTest. The assembly Astronomy contains the SunCalculator class which performs the actual calculation. The assembly AstronomyTest contains several unit-tests that validate the calculations against external sources.

SunCalculator is a single class that does not depend on external classes. Although this somewhat goes against the Single Responsibility Principle, it makes reuse of this class easier. The SunCalculator class needs the longitude, latitude, and time-zone of your location. You should also indicate whether to use daylight savings. An instance of the SolarCalculator can be created like this:

const Double Longitute = 5.127869;
const Double Latitude = 52.108192;
const int LongituteTimeZone = 15;
const bool UseSummerTime = true;

SunCalculator sunCalculator = new SunCalculator(Longitute, Latitude,
LongituteTimeZone, UseSummerTime);

You have to supply the longitude and the latitude from the location that you want to calculate the sunrise and sunset time. These are the two first arguments of the constructor. For locations that use daylight savings, you should set UseSummerTime to the actual daylight savings status. For locations that don't use daylight savings, set it to false.

The actual calculation of sunrise, sunset, and maximum solar radiation can be seen below:

DateTime sunRise = sunCalculator.CalculateSunRise(new DateTime(2010, 4, 1));
DateTime sunSet = sunCalculator.CalculateSunSet(new DateTime(2010, 4, 1));
sunCalculator.CalculateMaximumSolarRadiation(new DateTime(2010, 1, 26, 16, 30, 0));

The DateTime that is returned from CalculateSunRise and CalculateSunSet includes the sunrise and sunset time. For more information, take a look at the unit-tests in the assembly AstronomyTest.

## Points of Interest

The code first calculates the declination of the sun, cosine of the sun position, sinus of the sun position, and the difference between the solar and the actual time. All these parameters are used to calculate the sunrise and sunset times.

If you want to see the plug-in live, see my blog www.semanticarchitecture.net. The data that is retrieved and shown on the map comes from LetsGrow.com, the company that I work for.

## History

• v1.0 02/04/2010: Initial and first release
• v1.1 28/05/2010: Added a test case for Los Angeles, and a Console application that demonstrates the library in the source code
• v1.2 08/11/2011: Fixed failing tests

## About the Author

Architect http://www.hinttech.nl
Netherlands
Patrick Kalkman is a senior Software Architect with more than 20 years professional development experience. He works for Hinttech where he develops state of the art web applications.

Patrick enjoys writing his blog. It discusses software architectures using semantic web technologies. Patrick can be reached at pkalkie@gmail.com.

Published Windows 8 apps:

Published Windows Phone apps:

Awards:

Best Mobile article of March 2012
Best Mobile article of June 2012

## Comments and Discussions

 First PrevNext
 My vote of 5 ridoy 9-May-13 9:53
 My vote of 5 Sperneder Patrick 30-Apr-13 4:02
 Re: My vote of 5 Patrick Kalkman 30-Apr-13 4:22
 How to calcualte LongituteTimeZone? fortuna_6 21-Jan-13 8:14
 Re: How to calcualte LongituteTimeZone? Patrick Kalkman 30-Apr-13 4:24
 My vote of 4 Christian Amado 23-Aug-12 11:54
 Re: My vote of 4 Patrick Kalkman 30-Apr-13 4:18
 Hi Patrick: squizfloats 17-Aug-12 12:53
 Re: Hi Patrick: Patrick Kalkman 30-Apr-13 4:22
 Solar radiation Ruben Tacq 3-Jul-12 21:11
 Re: Solar radiation Patrick Kalkman 30-Apr-13 4:19
 Wrong result madcat 23-Mar-12 12:18
 Re: Wrong result [modified] Patrick Kalkman 24-Mar-12 4:02
 Hyperlink Failure Vasudevan Deepak Kumar 29-Feb-12 4:34
 Re: Hyperlink Failure Patrick Kalkman 24-Mar-12 4:04
 wrong calculation Member 8165547 16-Aug-11 11:08
 Re: wrong calculation Patrick Kalkman 24-Mar-12 4:06
 I see an "update" for Nov 8, 2011.... henslecd 3-Jun-11 2:08
 Re: I see an "update" for Nov 8, 2011.... Patrick Kalkman 7-Jun-11 20:43
 Not able to get corret sunrise and sunset time Paresh Rathod 11-May-11 9:56
 Sky brightness Andrew Jones 19-Sep-10 4:55
 how to determine timezone martkoch 5-Sep-10 23:06
 Re: how to determine timezone Patrick Kalkman 6-Sep-10 0:58
 Last Visit: 31-Dec-99 18:00     Last Update: 20-Apr-14 11:44 Refresh 12 Next »

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Article Copyright 2010 by Patrick Kalkman