In: Physics
What is the difference between active and passive solar thermal applications? How it will affect the storage system?
Active solar thermal systems like water heaters absorb sun's energy falling on solar collectors (flat plate) and transfer it to fluid (water). The fluid is forced through the system to deliver hot water using pumps. Storage is an insulated heated water container. Another example is using solar panels to heat your home.
A Greenhouse can be taken as an example of a passive solar thermal system. The solar energy is trapped within glass and transferred passively to heat the greenhouse. There is no forced convection for transfer of energy/heat. The reservoir of energy is called thermal mass. Basically these are materials with high heat capacity to store heat. A concrete or stone wall acts as a storage for solar energy and also slowly heats the greenhouse.