Customer Reviews

Sun Position - High accuracy solar position algorithms - a resource for programmers and solar energy engineers (Programming by Example)

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"This book is an important addition to the literature on calculating the position of the sun at any position on earth at any time. Mr. Craig gives much credit to Jean Meeus's book "Astronomical Algorithms", a well known text on the subject. The two books are complementary in many ways, and I recommend both to anyone who needs to calculate sun position to any degree of accuracy. Essentially, Mr. Craig has simplified the rather complex sun position algorithms in Meeus's book into a set of Visual Basic programs. The book's simpler but lower accuracy algorithm is adequate for almost all solar energy applications and the higher accuracy algorithm is state of the art. When I wrote the sun position algorithm for my company five years ago, I used several reference sources, and certainly would have saved many hours if this book had been available. Bruce Rohr, President, Practical Solar, Inc., Boston, MA"

John's book is crazy detailed ... and crazy important. If you are building a solar array, it's pretty important to point it at the Sun. However, the Sun is a moving target and that movement is insanely complex. You can figure it out for yourself ... and be wrong or let John Craig tell you how to do it. It's your choice. By the way, he gives you two choices ... the easy way that is incredibly accurate or the hard way which is so accurate that it's fun just to see how he does it. In either case, this is the definitive work on solar tracking software. Bravo to John and now ... go get a life!

Whether you are a new comer or an experienced professional, if you are interested in tracking the sun, John Clark Craig provides the basics and the programming for doing so in his new book, "Sun Position". What I especially like about this short book is that it includes the actual code for two algorithms in the text: high accuracy (3 x 10-5) and low accuracy (2 x 10-2) degrees for determining sun positions. Internet references for the codes are also provided and make it easy to copy onto a screen or document thereby reducing the potential for typing error.

Craig follows up by providing step by step examples of each calculation into a Visual Basic program. Additional information is provided on setting up Visual Basic Express, and some common debugging tips are also included. This book is a sun-tracker's resource! It is a must-have for anyone working in solar energy, meteorology, atmospheric sciences or other related fields.

Vi Brown, Principal & CEO, Prophecy Consulting Group, LLC, Mesa, AZ

I spent a lot of time and energy researching all the bits and pieces of sun position algorithms published in books and around the Internet since my first job as a solar software engineer back in the 80's. This task was daunting due to the complexitites of implementing and testing these algorithms for high accuracy sun tracking purposes. Often, the documentation was poor, the sample data points were incomplete, and units such as radians, degrees, decimal minutes, and others were not explained with sufficient clarity to avoid hassles while translating all the astronomical formulas to the various programming languages. As a result, this book, Sun Position, is the book I wish I had been able to use when I first started working in solar energy.

Two algorithms are presented, one with 0.02 degree accuracy (about 1/25 of the sun's apparent diameter in the sky), and the other with 0.00003 degree accuracy, for the most demanding applications. Every variable is documented carefully, with example numbers for a test case, allowing you to verify your coding even if translating to another programming language. My goal was to provide an easy-to-use, easy-to-verify, easy-to-debug, and easy-to-translate pair of Visual Basic sun position algorithms. This is THE RESOURCE to have handy no matter what programming language you are using.

My passion has been, and still is to help bring alternate energy solutions to fruition. In addition to writing a bunch of popular programming books published by Microsoft Press, O'Reilly Media, and others, I spent quite a few years working as software engineer for several of the world's largest solar energy power production fields, including creating all control and data acquisition software for sites such as Carrisa Plains, Victorville, Sandia Labs, the Weizmann Institude, Qatar, and elsewhere around the world. These fields were featured on the covers of magazines including Scientific American and Popular Science back in the 80's.

Solar energy projects are springing up everywhere, from small panels for personal use, to giant fields of trackers and heliostats for the world's most important alternate energy projects. I hope this book finds its way into the hands of programmers just as eager as I am to help with the world's energy needs.

I have just finished reading and downloading the code for this publication. I have not (as yet) had a chance to verify the code and its calculations, but the text (and the author's experience) suggest that the algorithms will work correctly.

While the text is dry (as one would expect from such a technical subject) the biggest flaw, and why I rated this publication as I did, is that the author doesn't provide the code as a single package. He has the code broken into snippets and requires that the user/reader copy and paste those snippets (using individual url's) separately to create locally runnable copies. While the first half dozen snippets were merely annoying, the next dozen or so were just infuriating.

I assume that the author had a reason for such ridiculous behavior, but for the life of me I can't fathom what it would be.