Serpentine

A Serpentine arrangement is where the same tube "snakes" its way from the bottom of the panel to the top of the panel. Efficiency is reduced slightly as the top of the panel tends to be hotter and therefore has higher thermal losses. The pumped pressure drop across the panel will be greater than for a parallel tube type arrangement, which will limit the number of panels that can be placed in series. Purging air from the panel generally poses no great problems as there are no possibilities for the antifreeze mix to take a parallel path, so generally air is easily removed when filling.

Parallel Tube

This is the most common pipework arrangement. Two manifolds, normally 22mm copper pipe are connected within the panel by a series of copper tubes (8mm or 10mm are the most common sizes). The colder water is fed into the bottom and the hot is drawn off the top. It is simple and cost-effective to manufacture hence its popularity.

Hybrid/ Preheat Piping Layout

This is a variation on the parallel tube type. The cold and hot feed are both on the top, but the top manifold is crimped to force the antifreeze mix to flow down the frist 3 or 4 tubes to the bottom manifold. This increases the temperature of the output of the panel.