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Archive for May, 2010

5 things you need to produce solar electricity

If you want to produce renewable and free electrical power using solar energy, here’s a list of things you absolutely need.

1. Solar radiation

It’s obvious, right? No, it’s not! Not for many people!

Solar radiation is everywhere, but not everywhere it’s enough to produce electricity using solar photovoltaic module. All the modules are described by one most important parameter — output power, for example 200 Wp — 200 watts (peak). The peak subscript is used to specify that the solar module won’t produce that power at all time, but only in specific conditions. Those conditions are:

  • solar radiation intensity — 1 kW/m²,
  • radiation spectrum similar to the one reaching ground at 35°N lattitude in summer,
  • temperature of solar panels equal to 25°C (77°F).

Without using solartracks you won’t have that solar radiation intensity except for a very brief moment during the day. So you shouldn’t expect your solar module to produce the peak power during the whole day. (more…)

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  • I just finished reading a great book “The Self-Sufficient Life and How To Live It” by John Seymour. And I must say that if I was to choose one book about self-sufficiency it would be this one. It’s a great source of information for all people who, like me, want to live off the land.

    The book was written by John Seymour, “known and respected as the >Father of Self-Sufficiency<“, who spent most of his life in Great Britain. This is what makes the book most useful for me – the british point of view. Most books written in United States are focused on american climate that differs a lot from what I have in Poland. Large part of the plants that are described in such books won’t grow in my part of Europe, because I have shorter and colder summers than Americans do.

    The edition I own is said to be expanded with over 100 pages from “The New Self-Sufficient Gardener” and covers many interesting topics on the over 400 pages. As the first edition was published in 1976, I guess it was over the 35 years updated with all the relevant information. (more…)

    Passive solar: interior thermal mass

    Thermal mass on the interior of the building is able to store heat or cold, and then slowly release it back out to the surrounding air. Heat from a sunny winter day as well as the coolness of a summer night can be retained inside the insulated shell of the exterior walls if the building incorporates adequate thermal mass. Thermal mass is needed to prevent daytime overheating of the structure and to stabilize its ambient temperatures through nights and periods of cloudy weather.  The more mass is available, the more stable the interior temperature.  Also, the more directly the winter sun hits the mass, the higher the solar heat gain.

    Floors can provide a good source of mass. Concrete, brick, flagstone, or other masonry materials work especially well.  Any of these can be layered over with cork — an organic material that insulates well, and has the advantage of creating a softer surface underfoot.  Earth floors can be used, but do not perform as well.  Insulating beneath the floor helps to return the heat gains to the interior of the building more quickly.  Interior walls and houses are often framed with wood, but if built out of masonry materials such as rock or adobe, these can provide excellent mass, especially those interior walls hit directly by the sun. Concrete poured between studs is a quick way to add mass. (more…)

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