To provide adequate protection from freezing, most solar hot water systems in Nova Scotia are indirect or closed-loop systems. In a closed-loop system, a pump moves a non-toxic heat transfer fluid through the solar panels, known as collectors, where it is heated. After the heat transfer fluid exits the solar collectors, it passes through a heat exchanger where the solar heat is transferred from the solar fluid to the water supply inside your solar storage tank.
Closed loop, pressurized antifreeze systems are the most widely distributed solar heating system worldwide. The animation below explains how they operate.