Solar Plumbing

Domestic solar systems have been developed over the course of more than a hundred years under the influence of local plumbing practices and the developing national regulations that have followed to ensure safe and efficient practice. All of the systems that are currently used have their own strengths and weaknesses, there is no perfect solar system configuration, just good systems templates that can be adapted to work efficiently through proper site assessment, design and installation.

It should be noted that as systems become more and more mainstream, practices are evolving and simple systems such as drainback are becoming more popular with installers.

All systems typologies have similar subsystems that must perform a number of roles;

• Capture a percentage of the sun's radiation and transfer captured heat to a tank/ cylinder in an efficient manner
• Be robust enough to survive and function for a period of 20-25 years or longer
• There should be minimum storage losses, so that captured heat can be used the next day (or later)
• Survive boiling and freezing conditions
• Cope with daily thermal cycling of up to 150°C
• Survive boiling and freezing conditions
• The controller must sequence the operation of the pump to move the solar fluid only when solar energy is present at the collector and is required by the cylinder.

The systems themselves can operate with pressurised or non-pressurised loops that may be fully-filled or drainback or that in hotter climates may operate without a pump under natural convection. The next section examines common system types, highlighting in turn the important differences, before the individual components of the systems are considering in more detail in subsequent chapters.