Active solar is a term which refers to the use of solar energy to "actively" convert the energy in sunlight into other forms. It is contrasted to "passive solar" which refers to certain architectural design elements by which buildings make use of the sun's energy for heating, and/or cooling.

Typical active solar systems include:

• Solar cells: Generation of electricity directly from the Sun.
• Solar space heating: Using solar-generated heat for heating buildings
• Solar water heating: Using solar-generated heat for heating water
• Thermodynamic systems: Concentrate the Sun for a thermodynamic cycle.

The term is sometimes extended to include other renewable energy systems whose ultimate energy source is the Sun, such as:

• Wind energy: Using wind currents to generate electricity or do other work
• Hydroelectric: Using the energy of flowing water to generate electricity
• Biomass: Using organic materials directly to burn for heat or to generate biofuels to burn.

Also see:

• Energy
• Renewable energy
• Autonomous building