Question

How do active and passive solar hot-water heaters work?

Short answer

Active solar hot-water heaters utilize pumps and controllers to circulate water, which is heated in a heat exchanger connected to solar panels. Passive solar hot-water heaters do not use pumps or controllers but utilize natural convection currents to circulate the water, which is commonly heated directly in the solar collector.

Step-by-step solution

Understanding solar hot-water heaters

Solar hot-water heaters harness the power of the sun to heat water. There are two main types of solar hot-water heaters: active and passive.

Explaining active solar hot-water heaters

Active solar water heaters use pumps and controllers to circulate water or a non-freezing liquid. Solar panels collect and convert sunlight into heat. This heat is transferred to the water tank through a heat exchanger present in the pump, thus heating the water.

Explaining passive solar hot-water heaters

On the other hand, passive solar water heaters don't use pumps or controllers. Instead, they utilize natural convection currents to circulate the water. The most common type of passive solar water heater is the Integral Collector Storage (ICS) system, where water is heated directly within the solar collectors.

Understanding differences

The key difference between active and passive solar water heaters lies in the method of circulation of water. Active solar water heaters require electricity to pump the water or heat-transfer fluid in the system, while passive systems rely on natural convection currents.