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Sun Volt Solar Blog

earth, the final frontier

Clean Energy, Clean Environment

We are at a cross roads in human history, we can choose to continue on as we have been, or we can make a change to improve our future and quite possibly the future for several generations to come. We are here to promote energy independence, a better environment with a higher return on investment for your hard earned money. It is what I believe in, it is why I am in the solar business.

The Sun powers (almost) everything

29 Mar 08 | Commentary, Environment, Solar Electric, Solar Hot Water

sun image

When we talk about Solar Power, we are really talking about direct solar power. Using the sun’s heat to heat our homes or light to produce electricity. When you think about it, the Sun actually powers almost everything we do either directly or indirectly.

With the exception of Nuclear energy, all of our energy comes from the Sun. All of the oil, gas, and coal we burn is carbon based energy that was converted by photosynthesis and stored in short hydrocarbon chains, ready to be broken down by combustion and combined with Oxygen to form water vapor, CO2 and heat.

The bond between Carbon and Oxygen is so strong that a lot of energy is given off during the chemical reaction (combustion) when the atoms combine to form CO2. Conversely, to break the CO2 molecule back into Carbon and Oxygen requires a lot of energy. That is where the sun comes in.

Our Sun

Our Sun is about 93,000,000 million miles away. It takes light leaving the sun 8.31 seconds to reach Earth. The Sun’s diameter is about 870,000 miles, compared to Earth which is about 7,900 miles. The rate of the Sun’s energy striking Earth is called insolation. The average rate of insolation on the surface of the Earth is 250 watts per square meter. This takes into consideration the North and South poles, inclement weather and night time periods. When the sun is shining, the average insolation for any given location is about 1,000 watts per square meter.

Here is a little perspective. Currently, we (the human race) consume 15 TW (terawatts, one terawatt equals 1,000,000,000,000 watts) of power at any given moment. The energy from the Sun striking the Earth is 89,000 TW.

There are, of course, a few details. We cannot cover the entire surface of the Earth with solar collectors.

  1. Water covers 70 percent of our planet. Which means that 30 percent of the energy from the sun strikes land areas. 89,000 TW x 0.30 = 26,700 TW available.
  2. Mountainous terrain (too difficult to build on) covers about 10 percent of the land area, that leaves 90 percent available for use, or 26,700 TW x 0.90 = 24,030 TW
  3. Roughly 9 percent of the land area is Antarctica, which is uninhabited. 24,030 TW x 0.91 = 21,867.3 TW available for use.
  4. Lets assume that roughly 5 percent of the remaining land area would be able to be developed into solar power installations (includes roof top installations). 21,867.3 TW x 0.05= 1,093.4 TW

Then there is the matter of conversion efficiency.

  1. Currently Photovoltaic efficiencies (technologies actually in production) are at most 16 percent. 1,093.4 TW x 0.16 = 175 TW

There are 175 TW of practical solar power available for our use. This gives us more than enough room to grow. Additionally, some of the solar power that strikes the oceans and other water areas. This energy creates wind, evaporates water and generates waves. It is currently being used for wind turbines, hydro power and so on. There is also a big push to develop wave and tidal power. These applications would further enhance the amount energy we directly use from the Sun.

The long and the short of it; there is plenty of energy for everyone provided we use our technology to develop that potential and stop trying to blow each other up.

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29 Mar 08 | Commentary, Environment, Solar Electric, Solar Hot Water | Comment (1)

Books for the Solar Professional

27 Mar 08 | Solar Electric, Solar Hot Water

There are several reference books about solar energy and wind energy on my book shelf that I refer to from time to time. I find it helpful, especially when I am dealing with a complicated design issue, to do a little research. These books offer guidance and theoretical information which can greatly improve design considerations.

  1. de Winter, Francis, Et Al. Solar Collectors, Energy Storage and Materials, Cambridge, MA: MIT Press, 1990. This book is a great resource for theoretical problems. Very technical with lots of Calculus and Physics base equations for heat transfer, storage, black body radiation, etc. I like to pick it up and peruse through it once in a while just to keep on my toes. More for engineers than for the run of the mill solar installer.
  2. Lane, Thomas. Solar Hot Water Systems, lessons learned 1977 to today Gainesville, FL: Energy Conservation Services of North Florida, 2004. This is the bible on Solar Domestic Hot Water systems. There are a few pages devoted to space heating, but most of the book is for SDHW. Includes information on sizing, mounting of collectors, storage, pumps etc. If you are going to install a SDHW system, this book is a must
  3. Solar Energy International. Photovoltaics Design and Installation Manual. Gabriola Island, BC Canada: New Society Publishers, 2004. Excellent PV installation manual, covers both grid connected and independent PV systems. Has chapters on system sizing, battery sizing, mounting, wiring, etc. Great resource for anyone getting into the PV end of the solar business.
  4. Siegenthaler, John, PE. Modern Hydronic Heating for Residential and Light Commercial Buildings, 2nd edition. Clifton Park, NY: Thomson Learning, Inc, 2004. Great reference book on any type of Hydronic Space heating. Good design resource for heat load sizing, heat loss calculations, radiant systems, etc. I bought this because I am getting more and more inquiries about space heating. I have yet to read this one cover to cover, but I am working on it.
  5. NFPA. National Electrical code, 2008 edition. Quincy, MA: NFPA, 2008. I like to keep the latest edition of the NEC on hand and available. Section 680 deals with PV installations.
  6. Small, Lloyd L. Analytic Geometry and Calculus. New York, NY: Appleton Century Crofts, Inc, 1953. This is an old college Calculus text book that I picked up at a used book store. It helps me remember some of the math if I have any questions or problems working on a calculus equation. Fortunately, almost everything can be plugged into an excel spread sheet and quickly calculated that way, but every once in a while I find myself scratching my head over something.

There are numerous other online sources that are also available. These are huge files and if you click on the link it will start downloading automatically, only use these links if you have high speed internet. They are well worth the trouble to download and read.

  1. Photovoltaic Power Systems and The National Electrical Code: Suggested Practices
  2. A Guide to Photovoltaic System Design and Installation, California Energy Commission Consultant Report 500-01-020, June 2001
  3. Stand-Alone Photovoltaic Systems: A Handbook of Recommended Design Practices

Of course, there are many, many other sources of reference material and I could probably write a book about solar books. However, these are the ones that I find most useful.

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27 Mar 08 | Solar Electric, Solar Hot Water | Comments (0)

Sun Slates

20 Mar 08 | Solar Electric

atlantis solar sun slateAtlantis Energy Systems, headquartered in the Town Of Lagrange (Dutchess County, NY), is a key manufacturer of “Building-Integrated Photovoltaic” or BIPV systems. The advantage to BIPV is that in the integrated approach, the solar-power cells are built right into the glass, laminated like a sandwich. The finished piece becomes part of the building, serving a second function, such as roofing, shading, window glass or whatever an architect can devise.

One of their latest products is called the Sun Slate. These look like ordinary asphalt roofing shingles and attach to the roof sheathing in much the same manner. The difference is that they connect to an AC inverter via two wires. They can be used for both on grid and off grid applications. They are made to specification and therefore are more expensive than conventional PV panels.

They are another example of locally made renewable energy products that are available.

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20 Mar 08 | Solar Electric | Comments (0)

Yahoo Groups

14 Mar 08 | General

Several months ago, I was messing around on Yahoo! and found that there were several groups relating to solar energy, wind energy and so on. These groups post messages and exchange e-mails on ideas, questions, projects and the like. For someone who is just getting interested in solar energy, or someone looking to “Do it themselves” they are an excellent way to learn from people who are doing though open information sharing.

The Yahoo! groups that I belong to are:

  1. awea-wind-home. American Wind Energy Association, a great place to learn about wind power from the pros
  2. axialflux. This group is dedicated to making small axial flux wind turbines and using them. Good if you want to learn how to make your own well designed wind mill
  3. Biodiesel. Self explanatory
  4. microhydro. For those interested in small hydro electric generation projects
  5. homeenergysolutions. A good resource for renewable energy around the house, plus great ways to save energy by making conventional systems more efficient.
  6. SolarHeat. Solar thermal people talk about their heating projects.

There where also numerous PV groups, but I didn’t join any because it seemed like they were discussing old news.
One caveat, not everything that is published there is correct or the best was to do things. I have found that there are a few people that are attempting to sell snake oil. There are also a few well meaning people who don’t know what they are talking about. Generally speaking, however, the majority of contributors do know what they are talking about and are a valuable resource for somebody who want to do it themselves.

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14 Mar 08 | General | Comments (0)