MOD 3  LECTURE  6                               SOLAR ENERGY
 
"Solar technologies are broadly characterized as either passive solar or active solar depending on the way they capture, convert and distribute sunlight. Active solar techniques include the use of photovoltaic panels and solar thermal collectors (with electrical or mechanical equipment) to convert sunlight into useful outputs. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties, and designing spaces that naturally circulate air.

The Earth receives 174 petawatts (PW) (1x10*15 watts)  of incoming solar radiation at the upper atmosphere.[1] Approximately 30% is reflected back to space while the rest is absorbed by clouds, oceans and land masses. The spectrum of solar light at the Earth's surface is mostly spread across the visible and near-infrared ranges with a small part in the near-ultraviolet.[2]

Earth's land surface, oceans and atmosphere absorb solar radiation, and this raises their temperature. " 
http://en.wikipedia.org/wiki/Solar_energy
PASSIVE SOLAR ENERGY

"The common features of passive solar architecture are orientation relative to the Sun, compact proportion (a low surface area to volume ratio), selective shading (overhangs) and thermal mass.[19]" http://en.wikipedia.org/wiki/Solar_energy

THERMAL MASS, WALL OR HEAT SINK or TROMBE

"The adobe wall, stone wall and the dyed concrete slab are my thermal mass and will absorb solar radiation on sunny days in the winter and release their heat durning the nighttime hours. Thermal mass acts to control temperature swings from night to day. Conventional construction without the attention to passive solar design can over-heat durning the summer days and require mechanical cooling and cool down during the night in the winter requiring mechanical heating. Larger roof overhangs will block the sun from entering the house during the summer when the sun is high in the sky but allows it to enter the windows and warm the thermal mass when the sun's angle is low in the winter time. Obviously, good insulation is a paramount component to good passive solar design."


Adobe Walls and Thermal Mass Walls 


SOLAR PIT

The solar pit at left has barrels of water that act like a trombe to release heat at night.  Insulating batts further prevent heat loss at night. 

PASSIVE MECHANICAL SOLAR ENERGY Water heating

http://www.daviddarling.info/encyclopedia/S/AE_solar_hot_water_system.html

 
 
ACTIVE SOLAR ENERGY
http://encyclobeamia.solarbotics.net/articles/solar_cell.html
SMALL SOLAR ENERGY