How it Works

There are two types of solar water heating systems, passive and active. Active systems are more commonly used in cold climates like ours. Only active systems qualify for a rebate under this program.

• Active systems have solar collectors mounted on a roof or south facing wall. These collectors absorb the sun's radiation through a heat transfer liquid.
• The radiation is converted into useable heat energy by pumping the heat transfer liquid through a heat exchanger, typically located in a secondary storage tank.
• This heat exchanger pre-heats the water entering the conventional water heater system, reducing the amount of energy needed to bring the water up to the desired temperature.

There are two types of active systems commonly used in Manitoba:

1. Drainback System

   Drainback systems are typically used in cold climates when water serves as the heat transfer fluid. Drainback systems use pumps to circulate household water between the collectors and a water heater inside your home. To prevent freezing when the collectors get cold (no sun) and pumps are turned off, water will automatically drain from the solar collectors and piping into a reservoir tank located inside the home. Drainback systems must be carefully installed to allow the water to completely drain, and refill when the pump turns back on.

2. Glycol System

   Propylene glycol is a popular anti-freeze solution because it is nontoxic and very stable. The heat captured by the collectors and stored within this solution is transferred to the domestic hot water supply via a heat exchanger, which is commonly found within a solar storage tank. This heat-exchanger maintains the anti-freeze solution within a "closed loop" that is separate from the water being heated, while still enabling heat transfer. Due to its freeze protection properties, glycol can remain in the collectors at all times.