soLAR HOT WATER HEATERS: THE DESIGNS

Solar water heating designs

Main solar water heating designs:

- the batch ICS solar systems (an ultra-simple system for moderate climates);
- the thermosyphon solar systems (for moderate and other climates);
- the solar open-active heating systems (for moderate and hot climates);
- the drainback systems (cold climates);
- the anti-freezing pressurized systems  (cold climates).

Batch ICS solar systems

Batch solar systems (or ICS) are the simplest and, in a way, the oldest solar heating systems. They haven’t pumps, separated storage tanks or anti-freezing. They combine a solar collector and a storage tank into one single unit, and in their most simple version they are a mere water tank within a glazed box.

See, for details:

Batch ICS solar systems

Image Credit: EERE

 

Thermosyphon solar systems

Thermosyphon systems are also a simple solar heaters, very efficient and very popular in moderate and hot climates. They are cheap and demand no pumps or special controls, and can also be installed in colder climates.

See:  Thermosyphon solar systems

The open-loop direct system

If you live in a moderate or hot climate, without freezing problems, you may choose a simple solar heating water system using a pump and water at the collector level. This system is called technically an Open-loop direct system.

See: Open-loop direct solar systems

Antifreezing solar heating systems (Active-closed pressurized systems)

Cold climates demand more complex systems. Batch/ICS systems are clearly inadequate in freezing conditions, and thermosyphon solar systems involve some limitations.

One of the most popular solutions for freezing climates comprises a relatively complex system with an antifreezing fluid (glycol, usually), a differential controller, an expansion and a storage tank, and a heat exchanger and sensors and valves.

See, for details: Anti-freezing solar systems

Drainback solar systems

Like anti-freezing systems, drainback solar systems are also specially conceived for cold climates. They offer lower maintenance and longer life and reliability, but they pose higher demands in terms of design.

See, for details: Drainback solar systems