Close Coupled

Collectors and tank on roof

Passive system with no circulation pumps needed – thermosiphon effect

Main disadvantages are physical weight (up to 500kg) and appearance (tank on roof)

Winter boosting by electric element or gas

 

Split system

Collectors / panels on the roof, tank on the ground

Utilises a small circulation pump to transfer liquid (water or glycol typically) between collectors and tank

Collector panels (flat plate type) or evacuated tubes – both work well.

Winter boosting by electric element or gas

Heat pump

Works by using a compressor and refrigerant instead of collector panels on the roof

The refrigerant absorbs heat from the air and the heat is transferred to the water in the tank.

Efficiency is not much better than standard electric in the depths of winter, however efficiency improves as ambient temperature rises.

Main advantage is cost, easy to replace old storage unit on the ground. No tank / panels on the roof.