Portal:Solar

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The Solar Portal

The Sun photographed by the Atmospheric Imaging Assembly (AIA 304) of NASA's Solar Dynamics Observatory (SDO).
Solar energy, radiant light and heat from the sun, has been harnessed by humans since ancient times using a range of ever-evolving technologies. Solar radiation, along with secondary solar-powered resources such as wind and wave power, hydroelectricity and biomass, account for most of the available renewable energy on earth. Only a minuscule fraction of the available solar energy is used.

Often Solar powered electrical generation relies on heat engines and photovoltaics. Solar energy's uses are limited by human ingenuity, and the finite resourced to build the sys. A partial list of solar applications includes space heating and cooling through solar architecture, potable water via distillation and disinfection, daylighting, solar hot water, solar cooking, and high temperature process heat for industrial purposes.To harvest the solar energy, the most common way is to use solar panels.

Solar technologies are characterized as either passive solar or active solar, depending on the way the energy is captured, converted and distributed. Active solar techniques include the use of photovoltaic panels and solar thermal collectors to harness the energy. Passive solar techniques include orienting a building to the suns seasonal orientation, selecting materials with favorable thermal mass, which will capture and radiate solar energy, light dispersing properties that will disperse light energy, or designing spaces that naturally circulate solar heated air.

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Passive water heater diagram
Thermosiphoning is considered to be an appropriate technology. This process utilizes natural, renewable resources and the basic laws of thermodynamics to create movement of a heated supply of air or water. The energy source for this process is solar radiation: the energy of the sun is captured in a solar collection device and is transferred to either air or water via conduction. The entire process may be explained by the thermosiphoning effect: When air or water is heated, it gains kinetic energy from the heating source and becomes excited. As a result, the water becomes less dense, expands, and thus rises. In contrast, when water or air is cooled, energy is extracted from the molecules and the water becomes less active. It also becomes more dense, and tends to "sink." Thermosiphoning harnesses the natural density differences between cold and hot fluids, and controls them in a system that produces natural fluid movement.

The passive thermosiphoning of water is the process of heating and moving water within a system without the need or use of electricity. This process functions by utilizing natual phenomena such as solar energy, gravity, and an available water source. A solar collector, piping, and a water tank are materials required for the heating process. The flow of water is distributed into, within, and out of the solar collector. Cool water enters the bottom of the solar collector where it is then heated via convection by solar radiation. When water is heated it becomes less dense than cooler water, expands, and then rises (flows) through the piping. The heated water exits the top of the solar collector naturally. The cooler and more dense water sinks and remains within the solar collector until it is heated. As the cool water is heated, it expands, rises, is pushed out of the top of solar collector, allowing cool water to flow into the solar collector. This process continues naturally until the temperature of the water reaches an equilibrium with solar radiation input.

Hexayurt Project

The Hexayurt is a refugee shelter system that uses an approach based on "autonomous building" to provide not just a shelter, but a comprehensive family support unit which includes drinking water purification, composting toilets, fuel-efficient stoves and solar electric lighting. 8/15/07 Update: Winner of the Treehugger Participate! contest for Burning Man.

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Selected topics (Book)

Greenhouses: Construction of an Affordable Greenhouse · Humboldt greenhouse gallery


Passive solar design: Parras passive solar design gallery · Thermal mass · Thermosiphon


Photovoltaics: Energy · System energy · Grid connection · Holographic solar · Humbolt gallery · Maintenance · Panels · Parras gallery · Refrigeration · Vaccine refrigeration · Test field · Troubleshooting · Rural lighting · Water pumping


Solar cooking: Analysis of a solar cooker  · and development · and health


Solar dehydrating: Food Drying with Superheated Steam · Solar drying in Uganda


Solar distillation: Compound parabolic concentrator · Effect of water on light transmission of glass · Improving Basin Solar Stills · Solar distillation TB · Solar fuel alcohol distillation


Solar energy: Open Solar Outdoors Test Field · Smart windows · The solar resource


Solar hot water: DIY solar thermal collectors · Installation and Design Principles · System types


Solar power: Heliostats · Solar thermal energy

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