Passive Solar Water Heating Systems

Passive systems rely on natural circulation and gravity to move water through the system without requiring external pumps or controls. These systems are simple, reliable, and cost-effective, making them ideal for residential applications.

Batch Heater Systems

• How They Work:

• • A water storage tank is placed inside a glass-covered, insulated enclosure that absorbs solar radiation.
  • The tank directly heats the water, which is then stored for use.

• Features:

• • Simple design with no moving parts.
  • Direct heating of water in the storage tank.
  • Optimal performance in sunny climates.

• Advantages:

• • Low cost and easy to install.
  • Minimal maintenance requirements.

• Limitations:

• • Limited to warm climates, as the tank is vulnerable to heat loss in colder conditions.
  • Low efficiency compared to advanced systems.

Thermosyphon Systems

• How They Work:

• • Water naturally circulates as it is heated. Hot water rises to the top of the tank, while cooler water flows down to the collector for reheating.
  • The collector is placed below the storage tank to allow gravity-driven circulation.

• Features:

• • Flat plate collectors for heating.
  • Natural circulation eliminates the need for pumps.
  • Hot water is drawn from the top of the tank for use.

• Advantages:

• • Reliable and easy to maintain.
  • No energy consumption for pumps or controls.

• Limitations:

• • Requires proper installation with the tank above the collector.
  • Performance is dependent on site orientation and sunlight availability.

Comparison of Passive and Active Systems