Why not have the hot water cylinder on the roof?


There are several reasons for this.

  • Rooftop thermosyphon solar systems work satisfactorily, but a vertical cylinder works more efficiently (owing to temperature stratification in the tank).
  • Research also shows that circulating the water faster, via a small pump, improves the solar system’ efficiency by drawing heat from the solar collector more rapidly. This more than compensates for the small amount of power used by the circulating pump.
  • A rooftop hot water cylinder is extremely heavy, making it much more difficult to tilt the solar array to the optimum 45 degree slope.
  • Many roofs are not strong enough to handle the weight of a rooftop hot water cylinder, requiring structural work before being able to install. By contrast, a ’split’ evacuated tube solar system weighs no more than an adult person and is suitable for virtually all roof structures.

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    Where should the hot water cylinder be sited?


    Ideally, as close to the solar panel as possible — to limit heat losses.

    You will need to identify a route for the hot water pipes to get from the solar system down to your household plumbing. Your plumber may advise on the best way to do this.

    If the distance between solar panel and hot water cylinder is greater than 12 metres, then it may be necessary to purchase an optional larger (3 speed) pump.

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