Passive solar

From Wikipedia, the free encyclopedia

For the application of passive solar technologies in buildings, see passive solar building design.

[edit] Definition

Passive solar is a term referring to those technologies that can be employed to convert sunlight into usable heat, to cause air-movement for ventilation or cooling, or to store the heat for future use, without the use of much or any electrical or mechanical equipment. Technologies that use pumps or fans via significant conventional energy are classified as active solar technologies. Some 'passive' systems, however, do use a very small amount of conventional energy to control dampers, shutters, night insulation, and other devices that enhance solar energy collection, storage, and use.

Passive solar technologies include direct gain and indirect gain for space heating, solar water heating systems based on the thermosiphon, use of thermal mass and phase-change materials for damping indoor air temperature swings, solar cookers, the solar chimney for enhancing natural ventilation, and earth sheltering.

More widely, passive solar includes technologies such as the solar furnace and solar forge, but these typically require some external energy for aligning their concentrating mirrors or receivers, and historically have not proven to be practical or cost effective for wide-spread use. 'Low-grade' energy needs, such as space and water heating, have proven, over time, to be better applications for passive solar energy utlization.

[edit] Advantages and comparisons with active solar

Passive solar systems have little to no operating costs, often have low maintenance costs, and emit no greenhouse gases in operation. They do, however, need to be optimized to yield the best performance and economics. Energy conservation reduces the needed size of any renewable or conventional energy system, and greatly enhances the economics, so it must be performed first. Passive solar technologies often yield high solar savings fractions, especially for space heating; when combined with active solar technologies or photovoltaics, even higher conventional energy savings can be achieved.

Energy Conversion Edit
Solar power:	Active solar \| Barra system \| Energy Tower \| Photovoltaics \| Solar cell \| Solar panel \| Solar pond \| Solar power tower \| Solar thermal energy \| Solar tracker \| Solar updraft tower \| Passive solar \| Trombe wall
Wind power:	Wind farm \| Wind turbine
Hydroelectricity:	Marine current power \| Tidal power \| Water turbine \| Wave power
Biological:	Mechanical biological treatment \| Anaerobic digestion \| Biomass
Chemical:	Blue energy \| Fuel cell \| Hydrogen production
Geothermal power:	Earth cooling tubes \| Deep lake water cooling \| Ocean thermal energy conversion
Electricity generation:	Distributed generation \| Microgeneration \| Sustainable community energy system \| Seasonal thermal store