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Solar power and wind energy - DIY projects

Technology high and low: advances and homemade projects in renewable energy

Solar power and the wind energy are the basis for all life on earth!
A significant portion of equipment that can make use of solar or wind power does not require an industrial grade manufacturing equipment. With just a little mechanical know-how and knowledge of basic circuits, one can create devices that generate heat and electricity from the sun and wind. With a little more mechanical and electrical know-how, one can accomplish more complex and efficient feats, such as powering their house independently with solar and/or wind energy. Whether you’re an amateur car mechanic, took an electrical circuits lab, or are some type of engineer for electronics, there is a do-it-yourself project you could tackle to generate your own electricity and heat. Ranging from generators and power supplies to wind turbines and actual shingle-shaped photovoltaic units, the alternative energy movement is encouraging people to catch on. The technology is getting more advanced, perhaps at a greater rate with the rising prices of gas and other sources of energy.

Solar

There are two kinds of systems that make use of the sun: thermal solar systems and electronic solar (photovoltaic) systems. While thermal systems are simpler to build and tend to save more energy, photovoltaic systems are more complex and have a much more diverse use. The implementation of the technology is becoming more widespread. A plan to be built in Victoria, using the most advanced solar technology, is a photovoltaic heliostat solar power concentrator that will produce 270,000 MWh annually. Currently development is evolving as researchers seek alternatives to crystalline silicon devices. Thin films using CIGS, CdTe, and amorphous or microcrystalline Si are among the alternatives. The cells made in this way are called amorphous solar cells, and have a higher efficiency and longer life span than the crystal silicon cells. Other cells that are produced less often include edge defined film fed growth cells (EFG,) copper-indium selenide (CIS) cells, and dye-sensitized solar cells (DSSc or DSC.) DSCs have the greatest potential since they can be produced so inexpensively, but they do not have the high efficiencies that some thin films or hybrid silicon cells have. If manufactured right (i.e. not using a method that involves incomplete filling of small spaces with nanoparticles of titanium oxide) hybrid cells can be among the highest efficiency ranges (along with monocrystalline silicon cells) of 15-18 percent. EFG cells have a slightly lower efficiency range, but do not require sawing of silicon wafers during production, and furthermore have a rapid crystal growth rate. Another type of cell, polycrystalline silicon cells (aka Apex cells,) are easier to produce, and are expected to be produced at a lower cost in the near future, although these rarely reach an efficiency level in the double digits. The CIS cells have a similar efficiency as the Apex, and also are expected to have significantly reduced production cost in the near future, however there is currently somewhat of an issue due to a limited natural supply of indium. Solar contractors are getting more business with these newer technologies, even in the US (and have come a long way since Reagan’s dismantling of the solar panels on the White House.) In California, the state has made it illegal for homeowners' associations to ban home solar devices.
Many solar devices can be made without industrial equipment, especially the solar thermal systems. Depending on your education and skill, the efficiency will vary. Regarding photovoltaic, some more crude (although less demanding of skill and experience) projects call for screen printing in the creation of actual photovoltaic transfer medium. The average homemade solar system generates around 2 kWh. Thermal solar systems are more easily created, and are the most ideal for a first do-it-yourself energy project, or the aspiring amateur. Most thermal solar devices can be made with materials found in any scrap yard.

Thermal solar

More detailed plans in diagrams can be seen in the additional readings listed here and many more free plans can be found from a simple internet search.

Evacueted-tube collector

Wind

Wind farming is gaining more attention than it used to. Technology, distribution of turbines, and the number of wind energy farms have all rose significantly in recent years. Not all of potential energy from wind energy is able to be used as first noted by Albert Betz. Betz realized that the air that gets deflected from a turbine and the air passing through the turbine have a lesser velocity than the ‘free stream’ velocity.
The proportionality ratio is given as:

 

 

where U1 is the velocity far from the turbine and U2 is the velocity at the turbine. The relationship Betz gives for the power coefficient is Cp = 4a(1 − a)2
Modern wind turbines can generate 1-4 MW of energy. Global Energy Concept’s turbine designed for low wind speeds features a planetary gearbox, single-stage drivetrain, and a permanent-magnet generator producing 1.5-2.5 MW. General Electric has three models listed on their website ranging from 1.5-3.5 MW. GE uses Volt-Amp-Reactive technology in their wind turbines.
Some parts can even be harvested from washer machines and rewired so that you can get the 12V DC from the part designed for 3-phase AC. Getting two bridge rectifiers 15A+ attached to the AC does the trick. Carving your own blades requires a bit of a skillful hand, but does not require professional experience. As far as how much power you can get from the wind, this of course depends on how windy it gets where you are as well as on your creation. Wind strong enough to move leaves (~5m/s) has a potential of generating 5 watts/second/square-ft, while wind strong enough to make trees sway (~20m/s) has the potential to generate 475 watts/second/square-ft. Before you imagine money blowing onto your lawn, based on Betz limits, only ~60 percent of that power is able to be harvested. Furthermore, depending on your machine, you may only be able to get 25 percent efficiency. Most do it yourself projects, completed successfully, are in the range of 30-50 percent efficiency. The best top-of-the-line professionally manufactured wind turbines can reach efficiency rates as high as 90 percent. Altogether, including friction and other draining factors, most people can expect to harvest a quarter of the available watts from wind. If you live in an area that has an average wind speed of ~9m/s or higher, building one or more turbines would result in you being able to obtain a considerable amount of power. See the additional readings for more detailed information on do-it-yourself wind turbine creation.
Solar and wind technology are becoming more of a necessity. Powerful companies are just now taking the first steps necessary to avoid an even greater energy shock than is already being faced. It may be wise for individuals to try their hand at this technology where it is within their power. Some more advanced mechanics are even turning their vehicles into hybrids. While it may be difficult to build a geothermal station in your backyard, most people have the power to build simple devices for other kinds of renewable energy use.
Further reading:
http://www.yourgreendream.com/diy_fp_rewire3.php
http://www.pvresources.com/en/technologies.php
http://www1.eere.energy.gov/windandhydro/wind_low_speed.html
http://www.gepower.com/businesses/ge_wind_energy/en/technology/index.htm

If they were to split a

If they were to split a house's current into AC and DC, there would be less energy used. AC for mainly heavy motors or elements, i.e. water heaters, refrigerators, stoves, furnaces, air conditioners. All others could use DC supplied by charged batteries.

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