How does a Solar Thermosiphon work?

The operation of a thermosiphon works on the principle that hot fluid rises while cool fluid sinks. Here’s a breakdown of the process:

1. Heating: The fluid is heated, causing it to expand and become less dense
2. Rising Fluid: The heated, less dense fluid rises to the top of the system
3. Cooling: The fluid then cools down, becomes denser, and sinks back down
4. Continuous Cycle: This cycle repeats as long as there is a heat source

How does a solar collector work?

When exposed to sunlight, a special solar coating on the collector panel transfers heat to a pipe matrix containing transfer fluid (water and glycol). As it heats up, the density of the transfer fluid decreases causing the hot fluid to rise up the matrix to a manifold at the top of the collector.

The collector upper manifold (HOT) is connected to the heat exchanger jacket inlet, the return outlet is connected to the collector lower manifold (COLD). At the same time, colder, denser transfer fluid is drawn into the collector matrix lower manifold.

Water Tank Operation

The enamel-lined, steel hot water storage tank is surrounded by a heat exchanger jacket all encased with 50 mm thick insulation of high-quality expanded polypropylene foam (EPP), and contained inside the marine alloy outer casing.

When the thermosiphon works, heat from the transfer fluid passes from the heat exchanger jacket to the domestic hot water.

The system produces lots of hot water throughout the year, however occasionally after a few cloudy days, it may need a boost from the 1.5kW standby electric heater.