Advantages

Passive solar systems are significantly less expensive than active solar systems which are characterized by collectors such as solar panels operating in conjunction with mechanical equipment. Because passive systems employ structural materials such as walls, windows and floors to attract and radiate warmth, they cost far less.

Types

There are three varieties of passive solar arrangements. A direct gain system features elements inside the house which collect heat, an indirect gain arrangement allows a fixture such as an outer wall to soak up energy, and an isolated gain setup employs an element outside the structure for heat retention.

Materials

Direct gain systems often use large solar windows or skylights to allow in greater quantities of energy for maximum absorption. Indoor brick, concrete or tile floors or walls can be used to collect heat during the day for re-radiation at night. Darker substances absorb heat. Lighter ones reflect it.

Energy transfer

For heat distribution, passive designs rely entirely on conduction through materials, convection through a ventilation system, or movement of heat through radiation. Mechanical elements are generally not employed.

Other ideas

Solariums, roof ponds, greenhouses, energy-efficient blinds, proper insulation and roof overhangs are all potential elements of a passive solar heating system.

Source:

Arizona Solar Center: Passive Solar Heating and Cooling

U.S. Department of Energy: How a Passive Solar Home Design Works

U.S. Department of Energy: Passive Solar Home Design