Heliotactic Press

Interdisciplinary exploration of solar energy conversion, photovoltaics, and integrative design, and scientific philosophy.

Google SketchUp: Where is the Sun? 2010/01/24

Filed under: Solar Education,solar energy — nanomech @ 11:49
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As a researcher and educator in solar conversion systems design, I am sharing my concern about Google SketchUp for professional use and energy analysis. Through a multi-week correspondence with an unnamed member of the Google SketchUp team, I have learned that the team is unaware of the accuracy of the algorithms underlying their ShadowInfo and ShadowInfoObserver classes, and do not have the resources to collaborate to attribute source documents to the error in their models. Simply put, they do not know if the sun is where it should be for a given location/time on Earth. These core algorithms relate the solar Equation of Time (describing the difference between apparent solar time and mean solar time) to latitude position, solar declination, solar azimuth, and hour angle. If you and your colleagues find this of interest, I would ask you to contact the SketchUp team directly (sketchup-help@google.com) with common concern, as I have not had success in encouraging SketchUp to make this important information transparent to the user base. Arguably, it would not be a challenging problem to solve, if the user base could simply see the “snippets” of geometry algorithms. However, I am concerned that there may be legal consequences to those who use SketchUp for professional applications (such as your own firm), should SketchUp be found to be in significant error when used to prove or disprove data.

From the Google SketchUp Team:

“We’ve done some investigation over the weekend, but we don’t actually have any more information to provide. We don’t have a particular reference document, paper, or source for our algorithms, so there isn’t a location to which we could point you for reference. Furthermore, the solar calculations were implemented early on in SketchUp’s development, and the people who initially worked on them are no longer with the company.”

Thank you for considering this unusual failing in an otherwise highly useful software piece.

Dr. Jeffrey R. S. Brownson
Dept. of Energy & Mineral Engineering
The Pennsylvania State University
nanomech@psu.edu

 

Educational Talk on Solar Energy 2009/09/13

Filed under: PV Education,Solar Education — nanomech @ 08:37
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Solar hot water systems, and the technologies that make them possible, hold crucial pieces of information relevant to developing advanced photovoltaic systems. For the most part, photovoltaics are still just “flat plate collectors”, collecting thermal heat in addition to electricity. This talk by solar historian, John Perlin, offers an important glimpse of the historical context of solar energy technologies.

Video interview provided by Eon’s Video Blog on bliptv.

Books on solar energy by Perlin:

A Golden Thread: 2500 Years of Solar Architecture and Technology (1980) Ken Butti and John Perlin (foreward by Amory Lovins). Cheshire Books, Palo Alto.

From Space to Earth: The Story of Solar Electricity (1999, 2002) John Perlin. (Aatec Press) Harvard University Press.

 

Educational Links on Photovoltaics and Solar Energy 2009/01/05

Filed under: PV Education,Solar Education — nanomech @ 21:35
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Where would be the best place to get an update of solar energy conversion, and photovoltaics in particular? That would be in a classroom, where you can ask questions and sort through the multiple topics of materials, sources of photovoltaic action (drift, diffusion, electrokinetic phenomena), and the difference between a cell, module, and an array. You would also be able to see that PV is only a tiny segment of an otherwise broad portfolio of technologies to make use of the sun for heating, cooling, making chemicals, making electricity from turbines, and so on. I offer two core courses at Penn State that deal with these subjects, but obviously there is a larger audience out there that would like information. Thankfully, we will be producing a web-based course dealing with photovoltaics, but that will be about a year off.

Therefore, I would recommend two web-based books for the curious, right now! The first is an educational project that began as an international collaboration between the University of Delaware and the University of New South Wales, funded by an IGERT grant. The site is called Photovoltaics: Devices, Systems and Applications CD-ROM, and the authors are Christiana Honsberg and Stuart Bowden. This includes interactive diagrams, movie clips of the silicon manufacture process, and a good review of solar energy. You will need to download Shockwave from Adobe. Up until recently, the Shockwave addition did not work for Macintosh systems, so I was more hesitant at recommending the site. But now: go for it! You will be busy for weeks. Note that the site is dedicated to silicon devices, and will not provide a comprehensive description of thin film PV devices and the principles of operation. That being said, the site is a gem.

The second book is not as web savvy, but does contain fantastic fundamental information on solar energy conversion. The resource is Power from the Sun by by William B. Stine and Michael Geyer, at California State Polytechnic University in the USA and IEA SolarPACES in Spain. This text is more like the classic paper text by John Duffie and William Beckman: Solar Engineering of Thermal Processes,1 in which multiple solar energy conversion technologies are described.

There you go, solar energy enthusiasts! Go to school and get informed on solar energy. But if you are tied up with other things (like life), in the mean time do some winter reading and find out how much potential solar energy has as a sustainable technology!

1. Duffie, J. A.; Beckman, W. A. Solar Engineering of Thermal Processes. (3rd Ed.) 2006 John Wiley & Sons Inc, Hoboken, NJ, USA.

 

Solar Jobs = Green Collar Jobs! 2008/12/28

Filed under: industry,photovoltaics,solar power,sustainability — nanomech @ 10:13
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As a researcher and instructor dealing with solar energy conversion, I am acutely aware of the immediate need (or ASAP) for a smart, flexible labor force–capable and trained to install and maintain our new solar technologies. Solar energy will be the heart of the new green collar job sector, as we will need to deploy PV and solar hot water technologies to residential and commercial buildings for a carbon-constrained future.

Analogy:
I want to use the familiar example of technologies for indoor air quality and thermal comfort: HVAC systems (Heating, Ventilation, and Air Conditioning). Think about how many air conditioning units are now an integral part of buildings in the country. Consider the labor force that is required for AC/heating installation, duct installation, monitoring and control systems (e.g. thermostats), and maintenance or repairs (hint: it is a huge industry). Now think about how little you think about these systems (because they just work). There is similar (perhaps even greater) potential for green collar jobs–earning a paycheck and helping society and the environment!

The Very Near Future:
Green collar jobs for solar technologies are here! Training is in full gear in states like California, New Jersey, and Florida, and is ramping up in Wisconsin and Pennsylvania. At Penn State, we are already working on a training course for PV installation, as well as an upper level college course in solar energy technology design.

Additional reading: NYT article on PV installers as the new wave of green collar jobs.