Solar Energy

The Solar energy is the one that uses the Sun as direct source energy.

These energy is used from the beginning of humanity from the house heat (through a correct house orientation), to natural illumination (direct or through mirrors) and also to create fire (through lens or mirrors).

Now days the use of this energy is focus on these systems:

• Thermal (solar), is one of the oldest use together with the wind and biomass energies. Inside these we have:
   
  • By direct heating, (windows, greenhouses, solar ovens, ...)
    To achieve that it have to be optimized the solar radiation by correct orientation, reflecting walls, mirrors or lenses.
    And the use of materials that let the heat rays (infrared) pass through, capture and hold and all these together with the isolation to avoid the heat to be loosed.
    This system is been used to heat the house, cook, make fire, ...
     
  • By delay heating, (thermal solar cells, Trombe walls, mass structure, solar chimneys, ...)
    The key on these systems is on the thermal inertia, that is the all materials capacity to keep and return an amount of energy.
    On the elements involved on the inertia we have:
     
    • Mass Materials, (walls, floor structure, ...) Is one of the more use because its great rate between cost and effects. Here is crucial the orientation, composition and design of the different elements. An special type of this system would be the Trombe wall that use the greenhouse effect to heat a wall to air-condition the house.
       
    • Gel, among these the thermal gel is the most use. This one is capable to keep heat and return it at a concrete temperature They normally are used together with other renewable energy as geothermal or direct wind energy.
       
    • Fluids, from water to several other compounds to avoid problems of evaporation and freezing (ammonia, lithium bromure, ...). They're normally used to transfer the energy from the energy in-take and the use point. (thermal cells, vacuum cells, ...).
       
    • Gas, as the air, that through its heating the density is reduced and start to suffer a going up move used as ventilation mainly. This effect is got by the solar chimneys. They can be used also together with other renewable energies as geothermal and biomass to air-condition that air flow.
       
• Photovoltaic (solar), is the Sun energy conversion to electric energy through different systems as:
   
• Solar Photovoltaic Cells, they are cells that use the photovoltaic effect (Sun direct light convert into electricity), They can be created with different technologies and materials to reach different effectiveness and production costs. Regardless the used materials, we can improve their effectiveness by a continue motorize tracking and the ray concentration with mirrors and lenses.
  Between all these materials we can find:
   
  • Doped silicon, one of the most used with a performance of 12%.
    There are three types because its crystallization; mono crystalline, poly crystalline and amorphous.
    To raise the voltage the silicon is doped. That method consist to replace some silicon atoms with other different atoms (known as as impurities). Depends on the impurity type we can have two types of semiconductor, N or P.
    Now, from june 2009, the European Union have a low cost solar cell at 1€/watt with a performance higher than 16% Crystal Clear Project.
     
  • Organic Polymers, This technology is under development but it has a great potential because its low cost price. There are many universities and teams working on it as Lee Kwang-hee on the science and technology institute of Gwangju, Somenath Mitra on the New Jersey Technology Institute, ...
     
  • GaInP2/GaAs/Ge its efficiency is up to 29,9% through a system call Next Triple Junction (XTJ) developed by Boing-Spectrolab. This company also ensure to have a new cell with up to 41,7% efficiency at a cost of 3€/watt but not telling with which materials.
     
  • InGaN and In-rich Group III-Nitrides alloys, under development by Lawrence Berkeley National Laboratories.
     
  • Zinc-Manganese-Tellurium combined with Oxygen atoms, this system can achieve up to 45% of efficiency. Kin Man Yu y Wladek Walukiewicz en el Lawrence Berkeley National Laboratories.
     
  • Cadmium-Tellurium that can get an efficiency up to 12% with a cost of 1€/watt, developed by a company call Abound Solar. This company sell only to another companies.
     
  • Titanium Dioxide known also as DSSC (Dye Sensitized Solar Cells) and DSC or DYSC, can be described as an "artificial photosynthesis". Made by three layers, on the top is a transparent anode made of fluorine-doped tin oxide deposited on the back of a (typically glass) plate and on the back of the conductive plate is a thin layer of titanium dioxideon. How to Build Your Own Solar Cell.
     
  • And different other combinations ...
     
• Thermal Electric Systems, these plants use the solar thermal power to, through complementary systems, produce electricity. There are two different types:
   
• Solar Power Plant, with a big mirror surface (heliostats) focus to a single point to heat up a fluid to move a turbine creating electricity.
   
• Wind-Solar Tower, Creates electricity through a wind turbine inside the tower. To move this turbine there are two systems to create an strong air flow by heating it and creating a big pressure gradient because the high from the ground to the turbine.
   
• Illumination (solar), is one of the most commonly used. The use of Sun light as illumination source give us not only a money save but also a better quality illumination together with its healthy effect on persons.